I have decided after going through a few upper soundstage speaker that I want to build my own component sets. There is a few things I need to understand before I go about making equipment selection, setting crossover points, and creating a good average ohmage and power handling setup.
I want to build a very efficent three way component set, in the 60-90 watt range of overall power handling, and with an average ohmage between two and six ohms. I have a decent amp to power them, a JBL LCA752. It's rated at 75x2@ 4 ohms, and 90X2 at two ohms.
What I am having trouble understanding is what power range of drivers to get to make this work properly. Lets say I build a 2 ohm component set with a power handling goal of 90 watts. Do I go for a rating of 30 watts for each driver, a little more or less for all of them, or divide the power for each driver differently, say like a 40 watt midbass, a 30 watt midrange, and a 20 watt tweeter?
Another thing I am having trouble understanding is good crossover points, and what capacitors/inductors to use to accomplish these points. I am sure that I would want to set these up based on the frequency plots of each individual driver used.
Replies (40)
swez on 09/21/2007 19:45:39
This is asking for a lot of time, research and effort to do such a system. The results are well worth the work if it's done well.
Noting the amps mentioned, I would be tempted to suggest an easy but effective method. Use both amps here and active/passive crossovers as needed. In this case, Bi-amping would be your best bet. (Meaning, an amp dedicated to MB only and a 2nd amp to power the (MR/TW) If using subs, this is actually a "tri-amp" configuration. (Subs, MB, MR/TW)
To start off with the basics, will need to pick out speakers that match the amps in power and ohmic loads. Also, here's a general list of frequency crossover points to consider for each driver:
SW: 30 - 60 Hz.
MB: 60 ~ 300 Hz. (6.5" - 8.0" drivers)
MR: ~300 - 3,000 Hz. (4.0" - 5.25")
TW: 3,000 Hz and up (3/4" or larger)
The crossover points are not fixed in stone and can be adjusted a bit, depending on the drivers used for each segment of the system. The "MB section" needs the most power as it will be producing some prominent lows. The MR/TW amp does not need to be so strong as these speakers are often very efficient and do not require large amounts of power to get the SPL levels up to snuff.
FYI: For best MB performance, it would be best to mount them in sealed chambers, a seperate set of boxes or well sealed doors. (Back doors or rear deck) A free air MB install will not take much power and not have the gut punch factor either.
Now, we should look at the drivers as separate pieces in this puzzle. It will be very difficult to find MB,MR & TW's that are 2 ohm units and these would be probably be low production units too. (That makes for high cost per unit) So, 4 ohm drivers are the likely option for each. A 4- 8 ohm MR/TW would be OK too. (Mids/Tweets are very efficient, so amping them to get the desired SPL is not an problem) They are likely to be cheaper and easier to find as well.
The next hurdle to look at is filtering needs for this proposed system. Here, a 12dB/octave slope makes good sense. They are effective, easy to work with and the slopes are not so difficult to match with amps used. (2nd order Butterworth alignment filters are cost effective and easy to get low cost parts too) Most amps have 12dB filters as well. This makes things easier also.
If each amp has adjustable HP/LP filters, they can be used as part of your filtering needs. We can choose HP or LP for the MB driver and then use a cap/coil passive to block highs or lows as needed. (Pick one that make the most sense) I would use HPF's here. This makes things easier to fabricate when using passive crossovers.
For the MR/TW drivers, the amps HPF makes the most sense if it is variable and can block below 300 Hz. If not, we have to take a different approach and employ all passives or an active/pssive filter network to make this work properly.
Read this link below carefully. It explains the basics of passive crossover design. It's likely to be a bit difficult to understand on the first pass. Some carefull reading and thought will stretch the mind, but not impossible to grasp:
http://www.bcae1.com/passxovr.htm
After reading this a link a few times, it will become more clear what is to be done. In a nutshell, coils pass lows and block highs. Caps pass highs and block lows. The Cap & coil and variable components based on the frequency ramge they pass/block.
Speaker ohmic values are generally considered as fixed loads. (This is not true in the real world, but for this application, we can work the numbers as if they are fixed and still get very good results)
Got all that?
Swez
PS This is very complex to the average non-tech. However, a little reading and number crunching will get you through the process in good shape. (Are you ready to take a big bite off this pumpkin?) SMILE
SQLThump on 09/22/2007 03:34:04
Gotcha loud and clear, and after some consideration, I think maybe I should take my first comp set a little easier, and go with a two way set. I think some of the complexities will be biting off a little more pumpkin than I can chew. I do not consider myself an average non-tech, but more an above average non tech, and this sounds like a great learning expeirence, and something that will be far more rewarding than buying my own component sets.
The way you described the drivers as their own peice of a larger puzzle shows we are in the same book, so I will do some homework, and try to get on the same page. I was thinking that 2 ohm drivers may be a bit difficult and expensive, so its not really a problem to chuck that out the door.
Also, I really don't want to bi-amp these, as procuring a second amp would defeat the purpose of doing this on a low budget. The second amp I have now is barely functioning at this point, and will very soon go the way of the dinosaur. So for the sake of ease of project completion and budget, I am beginning to like the idea of a two way set more and more.
I want to mount the set in the stock locations, after I put together a little plate to flushmount them on, and a small enclosure to mount them in. 5 1/4 speakers can fit tin the factory locations I found out, as that is the speaker size I am currently running. I stuffed a nice amount of polyfill behind the speakers to isolate the rear wave, and to help seal the situation up a little sisce I cant use the factory screw holes.
There is a suprisingly large amount of room in which to make some sort of enclosure under the factory speaker holes as well, so making a sealed enclosure with a decent amount of airspace wouldn't be that hard to make. I will make a diagram and send it to you to give you an idea of the picture in my head here.....
I had been doing a little reasearch before posting, and have begun eyeballing a few different options for the MB and tweet parts of the puzzle.
I was thinking of going with these Audax AP130Z0 5-1/4" Shielded Aerogel Midbass dirvers for the midbass.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-155
The 7 inch version (I beleive it is a similar model...) is used in those wicked expensive ZVR10 speakers that Ravin brought to our attention in his "home theater" topic. A link to the article..
http://www.vonschweikert.com/zvr10.htm
Quote from the important part of this article: "The winner by a large margin is the Audax Professional 7" Aerogel-coned midrange driver. These rare and expensive units are hand-built in France and come with serial numbers; the Aerogel cone is a composite formed of carbon fiber, Kevlar, cellulose acetate pulp, and a ceramic binder. This cone is extremely light and thin, but does not ring due to the spongy internal composition; wave energy is absorbed, not reflected, by the random nature of the internal particles. This exotic cone is driven by an expensive edge-wound ribbon voice coil suspended in an enormously powerful magnetic field, larger than the magnet found on most 12" woofers!"
This makes this driver choice seem good to me....
As for the tweeters, I have a few prospects, but before listing therm, would like to go over some of the choices available in terms of construction types and materials used. I want very bright and sharp highs, but do not want shrill, ear pain causing stuff that will drive me nuts in the long run.
So anyway, what do you think from here??
swez on 09/22/2007 09:19:39
I think this is a good project to research for a time, learn the basics of crossover design and move from the 2-way plan in the now, to adding a 3rd driver in the future. A well matched 2-way system can be done on a moderate budget. Ash has proved this on several of his projects to date. Am sure he is more than willing and able to guide you along this path since he has been there before.
A good pair of 5-1/4" woofers can be used for both MB/MR functions. Here, if you cross them at 80 Hz., and use a quality tweeter that can handle good power at say 2,500 Hz, the audio spectrum is pretty well covered in the front stage. The sub(s) will do the rest.
Some guys use the rear speakers for MB only. That is an option if the front MR/TW's are strong enough and well amped. Unfortunately, to get adequate punch from the rear MB drivers, they will need to be amped too.
The Audax driver mentioned had a very flat frequency plot above 150 Hz. It has very stable MB/MR out to 1,500 Hz and still not bad up to 2,500 Hz. It is a 6 ohm driver though. When factoring in cabin gain, lower MB extension should be pretty good down to 80 Hz.
The mounting depth is 2-5/8" on this speaker. Chances are good you will need to make a baffle panel for the doors to get adequate clearance from the window mechanicals. (1/2" baffle plate?)
Finally, the efficiency of this driver is actually pretty good and flat between 150 - 2,500 Hz. (~87dB SPL @ 2.83 volts) The power handling is a modest 40 Wrms, so the SPL level at full power is just about 100dB @ 40 watts. (15.5 VAC) Peak SPL is more like 101 dB SPL @ 60 Watts peak. Not bad at all for this price. (19.0 VAC)
What say you?
Swez
Ash on 09/22/2007 10:29:21
There is a lot involved in making your own component set which takes quite a bit of patience, experimenting, and some form of testing & subjective evaluation.
You can wing it with a simple 2-way if sensitivity of both MR/TW are matched closely. However, in my experiences a lot of the available specs is very subjective since we are working in the auto environment. Placement is everything as we know and can make or break a design. The given frequency plots rarely give the normal off-axis listened to in the car. It will help much to use higher quality drivers to ensure low distortion and a smoother frequency plot (still no promises).
Hints:
If you are looking for a good detailed midrange to work in a 2-way, you may want to stay in the lower Q's as these normally have more a detailed smoother response although less lower mid bass. Expect real output limited to 120-200hz on the low end. Not a bad trade-off if you have a somewhat robust sub that can bridge the gap. Here you factor in cabin gain and lean (12db) x-over slopes to help.
Go with "infinite baffle" mids (Qts greater than .6) you will have to be carefull as these can often can exhibit a peaky response with a higher FS. Though they might exhibit more mid bass the response may not be as smooth and harder to blend with the sub as they are both playing in the same range. The latter may seem like a good aspect, but in reality it can insert more problems as phase and time delay become more of an issue. You do want a gap somewhat as there still will be rise in response from the sum of the two. This holds true for the MR/TW match as well in both the low and high Q drivers.
Power handling is going to be affected by three factors: thermal, usable xmax, and x-over slope. As of now I am using higher Q (.7/ tested .57 in doors) Audax mids with an xmax of 4mm. Before I had lower Q (.38) with the same throw and to be honest with you the higher Q's are more impressive if ran without a sub. I am seriously thinking about switching back for the lowers had better definition.
What it is putting out is more important than how much xmax. It will take more xmax to produce lower bass than upper bass of course, but if you don't need the lower then it is just wasted, so you can see how that can be misleading. If your'e trying to get more output in the 150-200hz range then you will have to check out the available frequency plots and see what is the driver's nature.
I won't go into enclosed drivers as that will have to be tested to ensure accuracy (perhaps with the Dayton WT3). I will tell you this, your lower Q's are your best friend as they will require way less air space.
Almost forgot another important point. Do not mistake sub bass for mid bass. You really have to train your ears to decipher the two. This is something most mistake and are never satisfied as they are "chasing a dragon". Understand that with mid bass units (especially in 3-ways) you should be only trying to supply the fundamentals of the upper bass region & lower midrange (the snap of the initial drum strike/ male vocal & so forth). Beyond that and you will introduce blending problems.
The sub takes over the rest unless you are using a steep order (18-24db) and low x-over point 50-60 and under. This is especially true if you use a box/driver alignment that will already lack any upper bass range.
This helps? Maybe not, but if you got any questions just ask.
Ash,
swez on 09/22/2007 14:53:15
Good feedback there Ash... knew you'd be adding a few pieces of this puzzle at some point. ;-)
Interesting how the Qts measured 0.7 initially and in the door, it dropped to 0.57. How did you get a to 0.38? (Sound a bit muddy there?)
Have a few Q's for you Ash... (If you have the time and tools)
1. At what frequency point does the "cabin gain factor" begin to roll off? (Am thinking it peaks above 45 Hz and begins to decay to <+3dB in the 300 Hz., range) Can you verify that with your test gear? (Off axis testing is good)
2. Also, we know that 1 MR driver will net xx SPL at say 5 watts. (RF speaker only = about 90 dB) Suppose we feed all speakers the same test tone at 5 watts each. What is the SPL # now? (RF,LF, RR & LR)
Here, Pink Noise would be a good representation of overall gain in full range speakers. If we wanted to find cabin gain nodes, or MB/MR only, then incremental test tones would be used.
Are you able to perform such a test matrix? (No subs in this test, just full range)
Swez
Ash on 09/22/2007 18:14:10
The .7 Qts was the published data. When measured in the door it was .57 (contribute that to inaccurate data). This is why it's important to be able to test if you want at least somewhat accurate results.
The lower Q was another Audax driver which happen to be right on with the published specs. Actually bass wasn't as muddy as the higher Q driver. Yes there was a lack of low mid bass, but the 100-150 range was quite decent. The Q factor is an indicator of peak at the FS and with that being said, the hi-Q driver possibly had too much peak to blend with the sub and MR. Mouthfull huh?
The USB4065's crossover is limited (12db hi pass/ 200hz @ 24db lo) and there I believe the problem lay. I'll try the low Q's again with the new AC unit with a lower setting on the high pass (70-80hz @24db) and higher point on the low pass (300hz@ 24db).
As of now I haven't been able to test actual cabin gain as I have still not settled on a RTA program. That point would be very interesting as most only consider low bass gains. I would assume without being able to detect any other peaks it would be hard to attain a smooth response unless you have an broad range EQ and a subjectively trained ear.
I'm quite sure there will be an SPL gain from more drivers, how much would be hard to say. It could be easily estimated that each added driver will net another 3db, but I don't think it actually works that way in the real world when you consider the rears are usually faded out some. Plus listening position plays a factor as well; different path lengths between ears and all drivers.
Once I stop procrastinating I should be able to measure some of the anomolies mentioned.
Ash on 09/23/2007 08:33:49
Okay Thump....
I did the switch back to the original low Q Audax drivers and of course the difference was definitely an improvement. Using the x-over points mentioned above, they integrated much better.
The high Q drivers had more snap and lower mid bass, but sounded boomy when played between the sub & MR. Less detailed with overexaggeration with certain instruments.
The low Q had a more deep punch that better matched the initial impact of the sub. Upper bass was more smoother, yet not as anemic as one would think. 1 db lifts in the 120 to 180 range on the EQ gave it the presence needed to add to the MR.
My setup consists of active filtering with passives only between the small 4" MR & TW. If you are going to try building even a 2 way, I suggest you use an active crossover as this will take out the guess work and give you better matching capabilities. This will require the use of a 4 channel amp as MB/MR will need their own channel as well as the TW. Later you could easily convert it to 3-way by using passives between the MR/TW.
As for power handling, that depends on what the sensitivity and usable range that each driver will play in. I would say a minimum xmax of 4mm for mid bass driver to get decent output for low Q. Since mid to high Q's present more output in the FS region you may be able to get away with less throw.
Don't expect it to be dirt cheap. However, you will be able to attain a high quality/ audiophile setup for far less than you could buy one already built. The use of home audio is your best friend here too.
Here are some brands to check out for both MB/TW units:
Seas, Dayton, Audax, Peerless, Aurum Cantus, HiVi Research, TangBand, Vifa, Mach 5, etc..
SQLThump on 09/24/2007 02:24:29
Thanks for the great responses guys! Ash, your input is greatly appreciated knowing your prior expeirence with DIY components.
First, responses to you fellow's replies
Before I go any further I would like to state a few things. I do want to use the stock speaker locations at the top of the dash to keep the mids and tweets close together, and to maintain the "In Yo Face" imaging they provide. There is optimal space in the dash to give just about any neccassary airspace for a small enclosure.
Also, the speakers will upfire towards the windsheild, and possibly prevent beaming from the tweeters, and adds ambience that with even my current speakers makes the soundstage seem larger than it really is.
The doors are a different story. There is no place to mount any sizeable driver without some MAJOR door panel modifications, as there is no large, flat surfaces. I also want all of the music to come from the front, and would definitely like to refrain from using midbass drivers to the rear of the driving position.
I do plan to cover the upper bass lower midbass with a smaller sealed sub setup as opposed to using dedicated midbass drivers, so I think a nice set of 5 1/4 should be able to cover the frequencies above that. I will go over what crossover points I would like to use towards the later in this post.
Bi-amping is something I want to avoid, and I want to gain the expeirence from building my own crossover networks. I did go through the read you provided Swez, and I think I can get this figured out with decent results. Plus, buying a new 4 channel, a decent active crossover, and another set of Monster's to wire it all up would rack up quite a budget.
In terms of measurement, I really don't have anything to measure it with besides by ear, comparing it to a few buddies that have systems in their cars (namely my nieghbors FoCal comps he has in his Durango) and a good selection of different speakers to compare by ear in the car audio shop he manages. As far as test equipment goes though, nothing is available at all.
My goal here is to more or less to make a decent pair of listening speakers, with decently flat response, and most importantly, have fun doing so. But going for the perfect no dips or peaks greater than +/- 1db is definitely a bit beyond my ability.
And now, some of the homework I have done.
I looked at a few different drivers, but I am still liking the idea of the Audax AP130Z0 5-1/4. Their Qes (this is the right spec correct?) is at .57, which is the same as the in car high Q midbass driver correct? What size drivers are you using here? Would one be able to count on a slight drop in Q rating when installed?
I took into consideration matching up power handling and sensitivities on both drivers as closely as possible, and thought HiVi had a nice offering that could fit the bill well. It is rated at 40 watts, has 88db@2.83v sensitivity, and would match the Audax well at 6 ohms
HiVi TN28 Fabric Dome Tweeter
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-409
Just for easy reference, paired up with Audax AP130Z0 5-1/4" Shielded Aerogel Midbass drivers for the midbass.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-155
After readind the link Swez provided, I put the calculator on there to use and came up with cap. and inductor values for a 2500hz crossover point at 6 ohms. Here they are:
HP cap.: 5.31 Microfarad
HP coil: .76 millihenrie
LP Cap: 5.3Microfarad
LP coil: .76 Millihenrie
I am looking along at some of the different rolloff graphs and am of course noticing that they all have a dip aroung the crossover point. Would I want to cause a delay here or create some sort of overlap to compensate so there isnt a hole in the frequencies? If so, how big would I want to make this?
Thanks for all the help guys. Ash, thanks especially for measuring the differnet drivers for this purpose too. This is the "above and beyond service" that makes this best site around!
swez on 09/24/2007 07:40:07
Thump,
Cleaned up the duplicate posts and will address the drivers noted and your Cap and Coil values now.
Since these are 6 ohm drivers and both drivers have a good range crossover point at 2,000 Hz., (2.0KHz) that looks like a reasonable place to start. As I ran some numbers, it looks like you may have some adjusting to do, to find off the shelf parts to build your crossovers. Here are the initial values I came up with for both HP and LP filters:
http://www.bcae1.com/passxovr.htm
HPF:
Cap1 = 13.26 uF (C1)
Coil 2 = 0.48 mH (L1)
Load = 6.0 Ohms
LPF:
Cap 2 = 13.26 uF (C2)
Coil 2 = 0.48 mH (L2)
Load = 6.0 Ohms
The schematic diagram will look like the link below when wired: Just subtitute the new Cap and Coil values to compensate for 6 ohm drivers. Also note the TW is wired out of phase to the woofer to compensate for a 12dB/oct filtering network.
http://www.partsexpress.com/pdf/260-142s.pdf
The next step is the fun part... finding a combination of caps/coils to get the desired target values. Here, the Cap will need to be a non-polarized type and rated at 30 volts or higher. Here are some off the shelf products from PE that can be used:
C1 & C2: http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=027-342
(12.0 uF)
L1 & L2: http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-408&DID=7
(0.47 mH)
The Caps are of fixed value and 12.0 uF is well within tolerance of the targeted 12.06 uF. Use as is.
The Coils have a slightly higher value then projected, but the value can be changed by removing a few turns of these coils and then burnish the insulation and tin with solder to install. This coil is w/i the +/-10% tolerance range too. Ca be used as is.
A prefab PC board for 2-way crossovers can be used and save a lot of time:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-120
Your layout of components, (C1, L1, C2 & L2) are listed in this diagram:
http://www.partsexpress.com/tech/260-120.html
OK, this package seems to add up very well to the targets mentioned earlier. When we consider the tolerance factor of +/-10%, each component fits as is. If you want a closer tolerance value, the cost of the parts are much higher. (Adjusting your own inductor coils is an option)
Ran some additional calulations with the components noted above. The C1 & C2 values of 12.0 uF and L1 & L2 values of 0.43 mH will net a crossover point of 2,200 Hz., for a 6 ohm speaker. That is very good for the 2 drivers mentioned in your selection. (Pretty darn close I must say)
How's that hit you now?
Swez
Ash on 09/24/2007 08:55:21
The Qts should not change once installed in the door or whatever. Running infinite baffle in the doors is essentially a sealed box and regardless how big the space, the Qtc will not go below the driver Qts. This is why you choose a driver by it's Q, but not soley.
The question is how accurate is the company's measure. I bought a driver that was published at .7, but when tested it was .57. That could have been okay if the Fs was below 70hz. Keep in my mind that the response was for my vehicle and different cabin gains/ transfer functions will result in otherwise. A little hard to explain but if you can check out the measured frequency plots, you will see the difference.
A good site to see this is CDT. They have a link that let's you check out all of their mid bass specs and shows door installation and box plots. There you can see what I'm talking about as I might not be explaining this good. You will have to click on individual drivers to see the specs and plots. Pay close attention to the Qts and Fs of each driver as you notice the change in response.
http://www.cdtaudio.com/midbass_drivers.htm
Depending on how much mid bass you want, a 5.25" is only good for 2-way as it will not add much to the low end. If you want to cover a broader range or use a 3-way, it is almost imperative a 6" or bigger is utilized. I believe Tangband makes a very high throw 5.25", yet I don't think it's all that efficient enough to use passively. Goldwood makes one specifically for auto use that might be of interest.
SQLThump on 09/24/2007 13:52:50
Again, thanks for the responses. My computer is still acting screwy, so I can't chack any of the posted links. I will get back to you guys later tonight.....
swez on 09/24/2007 14:10:52
That CDT link is most helpful and the plots change a good deal based on the Qts, Fs and F3 numbers. (CL-5 & CL-50) I see what you mean and the only real way to compensate for the lack of lows is to port the speakers. (But now, we get a camel's hump effect as well) The plots above 100 Hz., are very good. But below that point, too much roll off. (The "in car" performance MB of these speakers is not all that impressive from past experience either) :-(
Looking at the Audax driver, the Qts is 0.41 and Fs is 57.6 Hz. However, the Vas is notably larger than either CDT speaker too. Note the usable range on the Audax as its F3 is more like 150 Hz. That tells me the Audax is an extended Midrange speaker, more than a Woofer or Midbass driver. (A fair MR, but not exceptional above 2.5KHz and below 150 Hz.)
Comments?
Swez
Ash on 09/24/2007 23:50:21
Exactly... Interesting how that works. You really shouldn't look at an mid bass unit like one would choose a infinite baffle sub.
The easiest way to skip around all this is to build some form of enclosure. With that you can better control the drivers output and put it where you want. My theory on that is to use the "solobaric" type setup (essentially low Q drivers meant for ported boxes, but with enough throw to take a sealed). That's another story.......
Thump, I seriously hope I'm not confusing nor dissuading you. There is just a lot of aspects to building from raw drivers which can become expensive if just doing guess work. Sometimes it is better to learn from others trials & mistakes than to waste ones own time & resources in something already proven.
For now I'll let all of this sink in and give you thought as what direction to take.
Ash,
swez on 09/25/2007 21:55:49
Well said "O Learned One" !!!
Remember our guy "Lessismore"? He said the same things and we are now believer's in the same basic fact... "Simplicity, is a virtue we can all strive to master". (K.I. S.S. is a great acronym to motto ... Keep It Simple Sam)
After looking at several offerings from PE, I noted there were trade offs to contend with in most every option in their 5-1/4" drivers. Some were poor low end response. Others were good midrange extension. But the driver's that did both well, cost a lot more too.
Also, to follow Ash's train of thought, enclosing speakers can help a lot when we understand the basic parameters of a given speaker and know how to minimize deficiencies and optimize the given traits of a specific driver. That knowledge does not come overnight and many will use trial and error at great expense and wasted time to prove their lack of understanding. (Don't become one of them unless a fat wallet allows it) hehe
Finally, a larger driver, (6" or more) can be a very good solution to this dilemma. Yes, some metal cutting or making fiberglass door pods may be needed to make that happen, but a solid 2-way system has many benefits if the design parameters are well understood. There are many good MB/MR drivers in the 6.5" range that would do very well here. It just takes the knowledge and patience to find them and fabricate as needed for the best results.
Swez
SQLThump on 10/6/2007 00:51:57
Sincere apologies on the long response time. Every time I log on, browse a few new posts, come to write on this, lose my connection and post, throw brick at computer, repair it, try again.............
First, I see where we are getting with this and was wondering if the gap between say 80-150hz was covered by an "upper bass" driver, as oppossed a dedicated midrange. This is something I have been thinking about for a long time, and would rather put a pair of 8's in an easy spot to put an enclosure (under or behind the seats) rather than go to cutting or building things.
I understand that this could be a "boomier" way to go about doing this, but I am fine with that. With my listening tastes, I prefer to have my insturmental (drums, bass guitar) to sound like boomy bass anyway, so this is something I would actually like. I love bass heavy music, so this would probably give me the optimum blend of "SQL vs. Thump" I do understand you can't have it all, thats why I want to design my whole rig myself, rather than deal with how Infinity or Alpine thinks my music should sound, because thats about my budget limit on this project.
Second, I guess i should have been more clear on the goal of this project. I was looking to try to build a set of comps for the price of some stout coaxials. I would rather not go the coaxial prefab way of things, but I don't want to go over the top with this project. Swez, I am sure you know the woes of working with an older Buick when designing a system, namely the one that the car hardly justifies the means. But, I will be driving this car for another year or so, and probably a lot after I get a "project car" and would like to make some improvements over the ghetto rig I currently have setup.
That being said, cutting doors and doing my first fiberglass job on my car could have a good chance of disaster, and this would be a hell of a punishment to a good running car that already has major visual flaws. It's just more time and energy than the car is worth. I could keep a more reasonable budget and save a few headaches by finding a nice coax setup. I would like to keep it on a simple daily driver status, but with some healthy sound and overall performance.
I am pretty sure that using upper bass drivers with this setup of speakers would probably help me acheive my goal of the ultimate low budget rap system. I seroiusly do not want to spend more than around $100 for for a new front stage, and would rather not buy a new upper range amp. if all else fails, it may be the Infinity's or the Type R's for me........
swez on 10/6/2007 11:15:51
Quote: "wondering if the gap between say 80-150hz was covered by an "upper bass" driver, as oppossed a dedicated midrange."
This depends on the midrange speaker used. Many 5-1/4" drivers can handle 80 - 5,000 Hz. signals, but the SPL level at the low end of this spectrum is often several dB down from what it can produce at say 1,000 Hz.
Knowing the frequency plots of a given driver are very helpful here. We also get the benefits of "Cabin Gain Effect" in the MB region, but that depends on the vehicle and installation location/techniques used. "Midbass" is the range between the sub and Midrange speakers used. (Typically 60 - 300 Hz., or 2-1/3 octaves) 6.5" and larger drivers are generally most suited for this range.
I get your point on investing a huge amount of time and money on an older car. (Have the same issues too) In this case, getting the most from what you have now is sensible plan. (It's hard to make a silk purse from a sow's ear)
As you mentioned, adding a pair of MB drivers in an enclosure and tooling it to fit in the rear doors or back seat foot wells does make sense. That can be done with careful planning and using MDF as your enclosure material to keep it low cost. (The trick is to protect the speakers from "damage and grit" from rear passengers feet)
The issue still remains about amping these speakers and a bandpass crossover network that makes sense. This could be done, using the rear amp channels along with your rear deck speakers. (Net 2 ohm load to your rear channels) Here, a "Tri-mode configuration" may also be considered, if the amp can be used that way. (Most can, but MB speaker ohmic loads must be taken into account... 8 ohm MB drivers in parallel, but MONO signal)
Finally, some coaxial speakers now come with removable tweeters. They are basically Component speakers, (External crossovers and phase plugs) that can be used as Coaxials or Comps, depending on the application. These are generally more high end speakers and worth the investment as they can be used in your next ride as Comps.
Swez
PS Chew on this one a while and then come back with your thoughts. If this were my project, I'd make it flexible in design and easily transferred to the next vehicle. Chances are that you can gut this car and sell it for dirt cheap as transportation, (W/o audio gear) spare parts or send it to a boneyard.
SQLThump on 10/6/2007 22:22:20
Doh! The quote was supposed to read "wondering if the gap between say 80-150hz was covered by an "upper bass" driver, as oppossed a dedicated MIDBASS."
So far, I am really liking where this project has been going and would like to use the Audax and HiVi combo. I have thought about doing coaxials, components detachable coaxials very seroiusly, but don't think it enough of a challenge, and much prefer the idea of a set of speakers custom tailored to my tastes.
Although, especially with the detachable comps, there is more to play with and tune and have fun with the learning process, at this point, it seems a little too much "connect wire A to terminal B, tighten screws, jam out" which I can get with my stereo now, and by other means. I want something to exersize my mind, my steady soldering hand, and after some hard work, be able to sit back and feel I have truly accomplished something.
I do have a decent system now, but after a year of improving it piece by piece, it has pretty much gotten to the point where everything but the upper range amp, H/U, and the wiring has to go.
I do plan on having this car for a REALLY long time, as it has been in the family since brand new, and I already am kicking myself for losing one car that was in the same boat. Plus, it has always been a great car in terms of sheer reliablilty (never really left me stranded), so I would like to turn it into the "upscale winter beater mobile" while I go insane on a nice "weekend-summer head turner"
Put some more work into the project last night and came up with some solid ideas for a good bass engine to go with the comps we came up with here. It's a bit unorthodox, but I think it will suit my tastes perfectly.
JBL Grand Touring Series GTO75.4 II
http://www.crutchfield.com/S-3XhvyQndXUw/App/Product/Item/Main.aspx?g=120&i=109GTO754&tp=115
I am already in love with this amp, hearng it pound out on a pair of Alpine Type E's in my buddies soundroom. Since he is the manager of the shop, I could score this at a deep discount, and it's class A/B technology I would prefer over an expensive, nonflexible Class D unit of similar power. Plus, in the odd case I did sell the car, this could make a great upper range amp in the future. On top of all this It would pair up nicely with the JBL LCA75.2 amp I am using for my upper range speakers, and plan to retain for the new comps. I great blend of old and new school technology.
HiVi M8N 8" Aluminum/Magnesium Woofer
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-446
I think for the upper bass drivers, these Hivi woofers will rock if crossed over around 50-60hz up to15o-200hz to phase in nicely with the Audax, and to be able to be powered by plenty of super clean amp power by the projected JBL amp.
I would get a pair of Fmods to compose the high pass element of the bandpass crossover, and then use the the variable crossovers in the GTO75.4 to find a good spot to phase in to the Audax's response, and vice versa with the LCA75.2
For an enclosure, I was thinking of something that would actually downfire into the rear footwells, again, as more of an "upper bass subwoofer" as opposed to a dedicated MB design. This would give me the bass heaviness I would desire, avoid any focused sound from the rear which I can't stand any more of late, and keep anybody's "Size 12's" (hehe, maybe we all have the same shoe size..) from deoing any damage to my treasured musical devices.
I got this inspiration from CplKittle's Kia, as he uses the 12's from 70 and below, and phases in the 10 at 70-200. Kit, if you've been following, am I correct?
Considering the other drivers, and their combined power, this should be able to work at providing me with the ability to enjoy detailed, level sound at a lower subwoofer knob setting, then be able to whip out the "this is way too loud" bass with a few minor adjustments.
I have been thinking about doing something like this for months, and I would use the Front RCA output to the upper range amp, and from there use the rear and subwoofer outputs to the bass amp, and use the A/B channels connected to the rear output to power the HiVi's, and then use the C/D channels with the sub outs to power a currently nameless subwoofer.
In terms of the lower end subwoofer, I am not too sure here, but I would definitely want something that will cover from nearly subsonic to around again, 50-80hz, with emphasis on the really low notes. Here I can sacrifice some accuracy, I just want as much of a 30hz earthquake as capable with the power allocated to the bass engine.
Problem is, I really don't know what brand of subwoofer to turn to for this really low bass, considering the power available. I am pretty confident that the usual subs I would turn to would to (Diamond D3, Infinity Reference, Alpine Type E) wouldn't be geared enough to said super low notes. Here, I am willing to spare no expense to find the perfect sub to rock the house, errr...automobile.
Considering the low range of frequencies it would have to cover, and the upper bass drivers there specifically for upper bass, I would want something capable of running in a bandpass enclosure tuned to an insanely low point.........
Time to find this sub and put it on a hit list. Would I want to look for a more SQ or SPL aligned sub driver though? I am truly clueless on this idea, as I would want it geared for insanely low bass. Is this where I start looking at brands like CDT, Focal, ect?
I will do some more research in the sub department, but it is on the last of the list in terms of priority. I just really want to get rid of them damned 20W Alpine coaxials..........
SQLThump on 10/6/2007 23:09:24
Well, I think I have found an ideal sub to pair up with this whole rig.
http://www.cdtaudio.com/pdf/EF-120%20specs_parameters.pdf
Looking at the frequency plots at this CDT EF-120 for a 1.5 cube sealed box, it seems like the perfect driver to match the plot of the HiVi M8N 8 inchers.
Coments?
swez on 10/7/2007 08:40:32
Mind doing and "Executive Summary" of the amps and speaker pairings?
General comments:
After looking at this new plan and such, The HiVi's noted would be a very good choice as Midbass drivers. They are very strong in the MB region and can handle good power too. The best amp to power them, seems to be the older JBL LC amp, bridged MONO and a bandpass filter network.
The GTO 75.4 is great for powering front comps and a 4 ohm Sub off the rear channels. This is a great amp and plenty of reserve power too.
As for powering the rear speakers, those Alpine's mentioned would be good enough for the rear fill and powered off the HU. (They are just that... rear fill)
About the sub, this CDT or the Infinity Ref 1250W would be a good options. The Ref is much cheaper and well suited for sealed, ported or BP. (Would not recommend BP here... poor SQ at the expense of a bit more SPL) The Ref 1250W will go low in sealed or ported box designs. Here, sealed makes a lot of sense:
http://www.crutchfield.com/S-lBHggv9aVXV/App/Product/Item/Main.aspx?g=520&i=1081250W&tp=111
Comments?
Swez
SQLThump on 10/10/2007 01:56:36
Executive summary... huh?
Ok here it goes....
Midrange: Audax AP130Z0 5-1/4" Shielded Aerogel Midbass
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-155
Tweeter: HiVi TN28 Fabric Dome Tweeter
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-409
Crossover parts for seperating the above listed:
C1 & C2: http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=027-342
(12.0 uF)
L1 & L2: http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-408&DID=7
(0.47 mH)
Circuit board:http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-120
Midbass: HiVi M8N 8" Aluminum/Magnesium Woofer
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-446
Amps: JBL LC-A752
http://ampguts.realmofexcursion.com/JBL_LC-A752/
JBL Grand Touring Series GTO75.4 II
http://www.crutchfield.com/S-3XhvyQndXUw/App/Product/Item/Main.aspx?g=120&i=109GTO754&tp=115
As for the sub I am still undecided. Looking at the out of car plot for the 1250W, and at that for the CDT, wouldn't the CDT feel a little more at home in the extremes bottom octave than the Reference?
I understand cabin gain will work in the favor of the Reference to hit the notes, but the CDT looks like it will be already dumping those super low notes out before it even comes near my car. I really want the super low notes to come out as hard as possible, and if the CDT will offer me that much more performance, I am more than willing to fork out the extra money. Here are the links for the manuals for both drivers.
CDT EF-120
http://www.cdtaudio.com/pdf/EF-120%20specs_parameters.pdf
Infinity 1250W
http://manuals.harman.com/INF/CAR/Boxes%20and%20Parameters/1250W.pdf
Tell me what you think here. If it's not much of a difference, I would be willing to go for the Reference. I have used it before, with the old JBL LC, in a BP box, and it did nicely, but the super low performance was kind of lacking. Also heard a pair of them in a freind's Camry, in the sealed enclosure, and again, kind of the same thing. That's why I was thinking a different driver, and probably need to think on this some more.
As for using the JBL LC for the midbass, thats a good idea I had not thought of, and will try when I get the whole setup. The amp is damaged though, and will overload when recieving too much low frequency input, but works like a champ for highs and mids. Can't hurt to try, so when everything comes in I will check this out. Definitely hopes this works, because It will be much easier to power up the 6 ohm comps properly with the GTO amp. Good thinkin man!
As for the bandpass filter, I was thinking of using the variable crossover on whatever amp ends up being used for the midbass drivers high pass, and using a Harrison Labs Fmod setup for the low pass section.
A link to this Fmod
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=266-256
Well alrighty then, I'm going to bed. Tell me what you think guys......
Ash on 10/10/2007 20:57:06
The simplest and in the end most economical & versatile way to do this is an external active x-over. There are several on the market that aren't really that expensive and have way more points to choose from than what you are opting for.
Depending on the amps internal x-over may limit you to what I have experienced before (undesirable frequency slopes and cutoff points). Is better to get a unit specifically designed for that use.
This can go a long way as you find yourself experimenting with different drivers, you won't have to keep changing amps or filters.
SQLThump on 10/11/2007 02:23:11
I thought about this too, and the idea is a bit out of budget for the project. Plus, I really don't plan to play with too many drivers for this car, as this will just be my daily bucket, and I plan to buy a new "project car" to really spend the dough on. Buying a crossover, and getting a new set of RCA's (god, quality cables are expensive!!!!) to set it up with is just a bit out of reach.
The crossovers on the JBL are pretty flexible, and I do plan to buy an older Alpine H/U with the EQ, crossover, 5V preouts, MP3/ WMA and all the bells and whistles as soon as one crosses my path. The search has been long, but I will find one!
Swez, in response to the using the old Alpines for rear fill, I do not plan to use them. My H/U makes much better sub output when the internal power is turned off, and I am using the old 6x9 holes for cabin ventilation from the trunk. I really don't like using rear fill much anyway, backseat passengers can just deal with it! GRIN
swez on 10/13/2007 21:07:12
Got it and that makes sense too. Front Comps w/ MB added would be nice in this setup.
Active Filters are nice, but the F-Mods act like Active filters as they are used at the input side of the amp and not passives on the speakers. The 12dB slopes are gentle enough to give a nice overlap too. If your HU has variable crossover points, that's even better than fixed filters like the F-Mod option.
Also, not using the HU amps, (defeated) gives a better quality signal to the RCA outs. This is true of most HU's that offer that feature.
Will look more closely at your details tomorrow as I am now pooping out after a very long week at work. This seems to be coming together very well, but a few double checks are in order before taking the next step.
Swez ZZZZZZ Good night to all
SQLThump on 10/14/2007 04:32:57
COFFEE My thoughts exactly. Sleep good man.
swez on 10/14/2007 12:07:11
OK, lets have a look at your details. I slept very well last night and ready to rock!
1. Crossover board (Good, if you want that option/expense)
2. Midrange: Audax 5-1/4" (Good between 300 - 2.5 KHz.) 6 ohms
3. Tweeters: HiVi (Good at 2.5 KHz to 20 KHz) 6 ohms
4. MB: HiVi M8N 8" (Good at 70 - 300 Hz) 8 ohms
5. Sub: That's a toss up... either sub noted is good. The key factor here is the right size box and placement of the box in your trunk. (Firing to the rear bumper, ported or sealed) [70 Hz., LPF]
Note: The MB drivers are solid when paired with the JBL LC-A752. This amp can be bridged MONO and the MB drivers wired in parallel for a net 4 ohms... a solid match. MB drivers are like woofers and can be used on a MONO channel. They are "Omni-directional" in nature and cabin gain will help the low end.
The LC-A752 amp has a selectable variable HP/LP filter. (32-320 Hz) Here, use the LPF function and set that to about 300 Hz. This cuts off the highs. Manual:
http://manuals.harman.com/JBL/CAR/Owner%27s%20Manual/LCA752%20om.pdf
Use F-Mod HPF, 70 Hz. as the bass blocking filter and use the amp LPF set at 300 Hz., and you'll have a nice active BP filter for the MB drivers: (Easy deal huh?) CLAP
http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=266-272
====================================================
Now comes the fun part... the front stage amp and crossovers.
The GTO75.4 II has good active HP/LP filters and we'll use the front channel HPF's, set at 300 Hz. This will block the lows to your 5.25" Audax MR. The HiVI MB drivers will be 70-300 Hz. The only thing you'll need here are passive HPF's for the tweeters. The target here is about 2.5 KHz. Since we have a 6 ohm tweeters and Mids. The proper Caps/Coils for a -12dB/oct filter are as followed:
Caps for 6 ohm speaker, HPF @ 300 Hz. = 44.2uF
This is not a standard value, so we'll have to come close. This is 47.0 uF and will do nicely:
http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=027-352
Another option is three 15 uF caps in parallel. That nets 45uF, if you have the space: (These are cheap if space is not a problem)
http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=027-344
Coil value here is 6.4 mH's. Lets see what we can find that comes close: Ahhh... 6.0 mH's is close enough:
http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=255-286
You can mount them on the noted prefab circuit board or wire them loose and then bundle them with hot glue and seal them with epoxy based paint against moisture. Either is good nuff.
FYI: Not sure how you arrived at the C1/L2 values but I used BCAE1 to calculate the values:
http://www.bcae1.com/xoorder.htm
Tech Tip: Most tweets need to be wired out of phase, (Reverse Polaity) with the Midrange when using -12dB passive filters. You may have to experiment to determine what sounds best in your ride.
Also, most passives have a tolerance factor variation of between 2-10% of target values. The tighter the tolerances, the more they will cost.
Whew... I gotta stop for now. Review the notes here, do some calculations if you like and we'll try to wrap up your parts list this weekend. This stuff fries the brain after a while huh?
Swez
SQLThump on 10/16/2007 18:16:44
Alright, I think this is all coming together then.
I originally came up with those C1/L2 values from the earlier post you left on the crossover parts needed. That point was 2khz, if I read properly. Either way, thanks for the redirection on the parts, and I'm extra glad I didn't order them last weekend.
Wait a second, I just got a little confused.
"Caps for 6 ohm speaker, HPF @ 300 Hz. = 44.2uF
This is not a standard value, so we'll have to come close. This is 47.0 uF and will do nicely:"
Considering we will be using the crossover on the amp, will we need a HPF at 300hz? I thought we would just need HP and LP at 2.5Khz.
I am considering just dropping the circuit board, and maybe building a slick looking set of crossover cases that could look like something Focal or Diamond would offer. I got more than enough plexiglass, plastic, old amps to part out for terminals and glue laying around to have enough to build a production line of components. I saw this spiffy little link on PE showing a really ghetto way to put together a crossover.
http://www.partsexpress.com/resources/building-a-crossover.cfm
Hey this guy put together something more ghetto than me, so I am sure I could make something wicked cool to show off my work on these comps.
As for the sub, I think I will try the Reference series first. They are some pretty decent subs, I just hope than can dump out the super low bass I demand. I will probably build a sealed box first, due to simplicity, and from there try ported then bandpass if nothing before it yeilds my "bass-head" requirements.
I was also thinking of using some lower crossover points for the lower end of the scale here. Would the Audax be severly impaired if used under 300hz and crossed over around 150-200hz?
Also, I was thinking a bit lower of a crossover freqency to cross over the sub and midbass, to where the 12" acts as a superdeep bass driver, so notes in the 30hz region are as powerful as possible, and the 8's provide really tight, contolled upper bass. I really like my music boomy, and if I can't make certain sounds thump right, I would kind of feel like a purpose was defeated.
I am more than willing to compromise a midbass fidelity for an increase in low end dumpage.
I dunno, but right now, my brain is also a little fried. It's been a long day at work, and I need a nap.
swez on 10/17/2007 05:30:14
Hehe, working all day/night will do that alright!
Yes, the crossover points can be shifted if you wish. (To a point) Here's a general outline to consider:
Sub: 35 - 70 Hz. (Sealed, Ported or BP) Low bass only
MB: 70 ~ 200-ish Hz. (The gut punchy bass part)
MR: 200-ish to 2,500 Hz. (Good power handling this way)
TW: 2,500 Hz and up
This will also mean changing the coil and cap values we looked at earlier. The F-Mod choice is limited to 50 or 70 Hz.
FYI: There is very little bass content in most music below 35 Hz. It takes a lot of power, sub cone area and a well designed enclosure to beef up that range in a subwoofer system. In Pro installs, we use 15's and 18" subs and several thousand watts RMS to get the SPL numbers to desired levels. (But this is large venue gear too)
In a car, we have to scale the sub(s) and amping power to fit the vehicle. Strong bass in a 300 ft^3 listening space, (Trunk and cabin area) is a challenge. Most use raw amping power and large cone area subs to get there.
In a larger vehicle like an SUV, Van or similar ride, we have a lot more airspace to work with and easier to get more cabin gain from them. Here, a modest amp and efficient sub designs can give very nice bass.
Swez COFFEE
SQLThump on 10/17/2007 16:26:12
Those crossover points were a little more in line with what I was thinking here.
As for the subject of superdeep bass, I am not sure of the true extent of the Hz cycle, but I have plenty of music that hits so low that I have only heard a handful of bass engines capable of even coming close to reproducing these frequencies. I would offer to send a couple of songs over to demonstrate, and get your opinion on the Hz that the bass is hitting, but all of it would probably be "a bit" offensive for your tastes.
As for making these notes pop, I think that 300RMS to a sub will do me plenty. I have never run that much power to a single sub before, and I have had a couple of systems that could do it. Also I have never run anything larger than a 10" sub that wasn't some form of house speaker. I am confident that if I follow the rules, laws and other practices, that I can get these notes to pop better than any of the ghetto crap I have used in the past.
As far as cone area goes, that is the reason I am going to check out a 12" sub instead of my usually favored 10". I looked into a few options for 15" inch subs within the wattage range, and really couldn't come up with anything I would like to use, or that would work well with the power I want to run.
I am also willing to go with a pair of lower powered subs if that is another effective way to get the cone area up in the higher square inches. The only sub I have really found that people make anymore in the 150W range are Rockford with their pathetic Punch Stage 1.
I am more than willing to go with a bigger/more subs sub if I can find one that will work well With the JBL GTO 75.4 amp I want to use. The one thing I really don't want to go bigger on is amp power.
As far as enclosure choice goes, at this point I am willing to try any of the craziest options a person can try to make the lower bass stand out in a midsize sedan. I really don't care what I have to do, and I will give up ANY trunkspace or cabin room neccassary to acheive such a goal. Show me some stuff, help me design it, and I will build it!
swez on 10/17/2007 19:42:33
The GTO bridged nets out at just under 300 RMS @ 4ohms. That's a solid place to be for the Infinity 1250w is a good match and a port tuned box, (30-35 Hz.,) offers a good low end bump. Unfortunately, Infinity does not publish their frequency plots. If they did, we'd have a better handle on what to expect in the lo-lo stuff.
Have heard some music cuts that have a lot of deep bass tracks and yes, they may go down to about 36 Hz. But this takes a good deal of amp power a larger format sub to get there.
Porting this 1250w is a good option, but sonic quality will suffer a little below 40 Hz with this sub. It needs a 2.0 ft^3 chamber, a 4.0" round port of 12" long will give a PTF of 36 Hz. That's not bad at all.
Swez
Ash on 10/19/2007 00:54:29
It would be beneficial to know exactly or at least close to what your vehicles corner frequency is. If you could do that you would be better able to plot out the sub you want to use.
It is almost unbelievable how easy a sub system will wind up being hit or miss mostly because of that factor, and less of how good or bad the sub is labeled to be. Go with a F3 rolloff too high (tight) above that point and low end will suffer. Go too low (loose), the bass will get muddy with normal music and may even exhibit a one note bass sound.
Your vehicles particular transfer function should play a major role in what sub you decide to use and how you want it to sound. This is very true since most sealed car audio subs are placed in a narrow range of Q's (Qtc= .8 - .9), yet rolloff frequencies can vary much.
As for ported, you try to get the one that digs down into the mid 30's and equalize peaks in the corner frequency range.
In that aspect, there are a lot subs in the 250 to 300 range that should suffice. You might just have to work them through WIN ISD or of the like to see what they are going to do.
SQLThump on 10/23/2007 18:38:39
Ash, how does one go about finding out a vehicles corner frequency? For the sake of having a killer system, I would be willing to do any and all reasearch neccessary. Do you go to like a car audio shop to have this done? Also, how exactly would you match the rolloff to the corner frequency properly?
And I think I am failing to understand the Q factor on the drivers. can one of you fellows explain to me what numbers are important, and how it affects a driver, and works for/ against cabin gain?
So here is where the project sits right now. I am more than likely going to order the speakers and crossover parts in about two weeks, assemble them, and go with the original plan of replacing my front speakers. Afterwards, in about another 6-8 weeks, I will buy the bass engine. I can get the JBL amp for a nice score of $150, and will have to fork another 2-300 or so on the low frequency drivers.
I am definitely going to shop around more for a sub, and research more on how cabin gain will affect the 200hz and under region before picking one out. I will be getting my computer that I can put WIN ISD on soon, and will also use it to design a nice box to go with it.
I would definitly like to go with something with more cone area, and PartsExpress had this tucked away that I didn't see for too long.....
Dayton DCS450-4 Classic 18" Subwoofer 4 Ohm
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-475
Wow, this is one big lookin' speaker Vern! It is within the alloted wattage, (300 RMS) great sensitivity (94db@2.83v), definitely conservative on the wallet (under $100), is a 4 ohm subwoofer and has raw cone area. Looks like it is a new product, as it has no frequency plots available and only has one review that is a little hard to take seriously. When I get my computer back up, I will expeirment with Win Isd and runs some different sub's specs through and check that out.
Ash on 10/23/2007 23:40:19
There is a simple method if there isn't a shop willing or able to measure your cars transfer function.
Using a simple SPL/DB meter and a test tone cd you measure the response (20-150hz) of a speaker (sub preferably) outside in an open field type area. Write down the frequencies played along with their corresponding output on the meter. You'll want to do this with no type of boost or cut, just a flat input.
Now put the same speaker in your auto and repeat the same test with recorded readings. You should see a difference in certain frequencies wether peaked or dipped. You should also notice how the lower end will have a rise (say maybe around 50-60hz) and continuing into the lower register.
There you will be able to tell where your car is starting to add a natural boost. Repeat if necessary to get consistent & accurate results.
As far as Q is concerned, it is just a way of describing the tonal quality that a relative size box/sub produce. More into that later....
That sub will require a very large enclosure and I doubt it will withstand the auto environment as it is really meant for home audio replacement. Another good replacement is this one for a large sub:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-560
Power is right up your alley and enclosure size is small. The rolloff (41hz) and Q (.707) are just right for extended lows. Might could go a bit smaller on the box if you wanted. Check the project link.
SQLThump on 10/24/2007 02:06:27
Ok, finding a shop to do this is going to be next to impossible, but with a little more in depth instruction, I am sure I can do this myself since my stepdad has a DB meter for setting up fire alarms...
Ok, so will any speaker do here? All I have available is junker crap, but if that will work, I will do this very soon. Also, do I want to measure the output at a distance comparable to the distance of the sub to the listening area, or get right up to the cone? One more, do I want to do this at full power, or at a low wattage?
That being said, I will do this ASAP, as long as I know the procedure, and after this, I am sure we can take some of the guesswork out of picking out a sub. Thanks for the info man! killer stuff!
swez on 10/24/2007 02:53:10
That Quatro 15 looks like a solid driver for the power you are working with. Also, the sealed and ported box space is tolerable to most trunk mounted sedan apps.
Ash is spot on with his recommendations on testing the woofer response parameters. Just test the SPL at various frequencies at about the same distance from the woofer cone. (36 - 40" away is good) One does not need to make this test at high SPL levels either. (95 - 100dB is plenty)
Here, one is testing the near field response of the sub/enclosure in an open air environ, then load it into the car and repeat the test again at same power levels and record both results as before. I would expect to see several dB more SPL in the car above 45 Hz and then tail off a tad at 100 Hz. (8-10dB SPL more gain in the car)
That SPL meter mentioned may not work well at low frequencies. There's only one way to find out though... try it and see.
Swez
Ash on 10/24/2007 04:58:31
Exactly......
This simple test method makes it easy to know already what your car will do to a particular subwoofer and how to adjust for it.
You might want ot check out radio shack for a meter. Wallyworld now sells one (Scocshe) in their autosound section, at least here they do. Not sure how consistently accurate it is though.......
SQLThump on 10/24/2007 16:46:02
The SPL meter will work, it will go pretty low, I used it to DB test my car a few months back, I only hit 116.8Db, considering the rig I am running, it wasn't too bad. It would give me different readings at different frequencies, and did the 116.8 at around 60hz, (I am guesing), and lost about 5 db on the lower note of the song I was playing. I could have gotten a much higher reading if I would of pushed gain and stuff higher, or went closre to thew subs. But I figured an accurate reading of what I usually listen at would be much better.
I thought of picking up one of the Schoshe meters from wallyworld, and it looked like a POS so I browsed right past it. The one Pops has is far better looking thanthat, and has a few nifty features.
Didn't think of checking Radio Shack though, I will have to take a look.
But yeah, if my crap drivers will work, I will try this out as soone as me and Pops have a coinciding day off.
SQLThump on 11/18/2007 19:04:58
Wow, major delays in the project. Spent waaaaay to much money on Halloween, and a few other recent occasions, so I will need another couple of weeks to get the spending money back up.
I do plan to test the corner frequency again, I just need to get some test tones as they all got "accidentally" deleted off of my parent's computer. DOH! Anybody got any links for some good ones? I know of one that steps down 10hz every couple of seconds, and even announces what the hz level is while it does it, but I may be hard pressed to find it again. It runs from 300hz down to 10hz.
So as long as I find the test tones I need, I will measure the corner frequency tommorrow.
On a side note, I hit a nasty pothole a month or so ago, and it hit with enough force to knock my battery hold down, the side mount terminal, and a few other things loose, along with disconneting a vital wiring clip that partially melted and caused my lights not to work. The car stalled in the middle of the road, and long story short, it sucked, but most issues were corrected the next morning when I busted out a nice once over.
But there was still an issue that was waaay out of line. My lights were flickering like mad after that on frequent, but not constant occaisons, (most of the time)to the point it seemed the car would nearly die, and triggered the ABS warning light for some odd reason, but on odd times would not have any problems at all.
Went and did another once over today, and realized what I had missed. the ground post was barely hanging on by thread. Had to unbolt a few things to tighten 'er back up, but now everything works great 100% of the time. Restored some lost faith in my car, and everything is working and running much better. Goes to show, that even with the years of working on car audio, that sometimes something so elementary can be missed, and then go on to cause a laundry list of problems until fixed. Definitely had me a rookie moment. Now I know if I have flickering problems again, to check the **** terminals.
swez on 11/18/2007 20:46:21
That's a interesting story and "who'd a thunk" a battery terminal was the culprit all along? It's an obvious point to check, but we often look for more complex issues first, chase the tail a bit and then go back to the fundamentals when all else fails huh? LOL
Swez
SQLThump on 11/19/2007 00:38:51
Yeah, it can drive a person mad when something like that happens. Dont get me started on some of my H/T lunacy that my reciever throws me................
swez on 11/19/2007 05:21:27
Hey, we all do it in one way or another. The problem often gets worse as we get more knowledge under the belt. We often tend to look for the exotic and rare or 1/10000th % rather than the simple and routine.
Why do you think most "genius" level thinkers suffer the greatest as they cogitate? They have too many levels to process the many "what if" scenarios and it drives them batty.
Swez
I want to build a very efficent three way component set, in the 60-90 watt range of overall power handling, and with an average ohmage between two and six ohms. I have a decent amp to power them, a JBL LCA752. It's rated at 75x2@ 4 ohms, and 90X2 at two ohms.
What I am having trouble understanding is what power range of drivers to get to make this work properly. Lets say I build a 2 ohm component set with a power handling goal of 90 watts. Do I go for a rating of 30 watts for each driver, a little more or less for all of them, or divide the power for each driver differently, say like a 40 watt midbass, a 30 watt midrange, and a 20 watt tweeter?
Another thing I am having trouble understanding is good crossover points, and what capacitors/inductors to use to accomplish these points. I am sure that I would want to set these up based on the frequency plots of each individual driver used.
Replies (40)
swez on 09/21/2007 19:45:39
This is asking for a lot of time, research and effort to do such a system. The results are well worth the work if it's done well.
Noting the amps mentioned, I would be tempted to suggest an easy but effective method. Use both amps here and active/passive crossovers as needed. In this case, Bi-amping would be your best bet. (Meaning, an amp dedicated to MB only and a 2nd amp to power the (MR/TW) If using subs, this is actually a "tri-amp" configuration. (Subs, MB, MR/TW)
To start off with the basics, will need to pick out speakers that match the amps in power and ohmic loads. Also, here's a general list of frequency crossover points to consider for each driver:
SW: 30 - 60 Hz.
MB: 60 ~ 300 Hz. (6.5" - 8.0" drivers)
MR: ~300 - 3,000 Hz. (4.0" - 5.25")
TW: 3,000 Hz and up (3/4" or larger)
The crossover points are not fixed in stone and can be adjusted a bit, depending on the drivers used for each segment of the system. The "MB section" needs the most power as it will be producing some prominent lows. The MR/TW amp does not need to be so strong as these speakers are often very efficient and do not require large amounts of power to get the SPL levels up to snuff.
FYI: For best MB performance, it would be best to mount them in sealed chambers, a seperate set of boxes or well sealed doors. (Back doors or rear deck) A free air MB install will not take much power and not have the gut punch factor either.
Now, we should look at the drivers as separate pieces in this puzzle. It will be very difficult to find MB,MR & TW's that are 2 ohm units and these would be probably be low production units too. (That makes for high cost per unit) So, 4 ohm drivers are the likely option for each. A 4- 8 ohm MR/TW would be OK too. (Mids/Tweets are very efficient, so amping them to get the desired SPL is not an problem) They are likely to be cheaper and easier to find as well.
The next hurdle to look at is filtering needs for this proposed system. Here, a 12dB/octave slope makes good sense. They are effective, easy to work with and the slopes are not so difficult to match with amps used. (2nd order Butterworth alignment filters are cost effective and easy to get low cost parts too) Most amps have 12dB filters as well. This makes things easier also.
If each amp has adjustable HP/LP filters, they can be used as part of your filtering needs. We can choose HP or LP for the MB driver and then use a cap/coil passive to block highs or lows as needed. (Pick one that make the most sense) I would use HPF's here. This makes things easier to fabricate when using passive crossovers.
For the MR/TW drivers, the amps HPF makes the most sense if it is variable and can block below 300 Hz. If not, we have to take a different approach and employ all passives or an active/pssive filter network to make this work properly.
Read this link below carefully. It explains the basics of passive crossover design. It's likely to be a bit difficult to understand on the first pass. Some carefull reading and thought will stretch the mind, but not impossible to grasp:
http://www.bcae1.com/passxovr.htm
After reading this a link a few times, it will become more clear what is to be done. In a nutshell, coils pass lows and block highs. Caps pass highs and block lows. The Cap & coil and variable components based on the frequency ramge they pass/block.
Speaker ohmic values are generally considered as fixed loads. (This is not true in the real world, but for this application, we can work the numbers as if they are fixed and still get very good results)
Got all that?
Swez
PS This is very complex to the average non-tech. However, a little reading and number crunching will get you through the process in good shape. (Are you ready to take a big bite off this pumpkin?) SMILE
SQLThump on 09/22/2007 03:34:04
Gotcha loud and clear, and after some consideration, I think maybe I should take my first comp set a little easier, and go with a two way set. I think some of the complexities will be biting off a little more pumpkin than I can chew. I do not consider myself an average non-tech, but more an above average non tech, and this sounds like a great learning expeirence, and something that will be far more rewarding than buying my own component sets.
The way you described the drivers as their own peice of a larger puzzle shows we are in the same book, so I will do some homework, and try to get on the same page. I was thinking that 2 ohm drivers may be a bit difficult and expensive, so its not really a problem to chuck that out the door.
Also, I really don't want to bi-amp these, as procuring a second amp would defeat the purpose of doing this on a low budget. The second amp I have now is barely functioning at this point, and will very soon go the way of the dinosaur. So for the sake of ease of project completion and budget, I am beginning to like the idea of a two way set more and more.
I want to mount the set in the stock locations, after I put together a little plate to flushmount them on, and a small enclosure to mount them in. 5 1/4 speakers can fit tin the factory locations I found out, as that is the speaker size I am currently running. I stuffed a nice amount of polyfill behind the speakers to isolate the rear wave, and to help seal the situation up a little sisce I cant use the factory screw holes.
There is a suprisingly large amount of room in which to make some sort of enclosure under the factory speaker holes as well, so making a sealed enclosure with a decent amount of airspace wouldn't be that hard to make. I will make a diagram and send it to you to give you an idea of the picture in my head here.....
I had been doing a little reasearch before posting, and have begun eyeballing a few different options for the MB and tweet parts of the puzzle.
I was thinking of going with these Audax AP130Z0 5-1/4" Shielded Aerogel Midbass dirvers for the midbass.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-155
The 7 inch version (I beleive it is a similar model...) is used in those wicked expensive ZVR10 speakers that Ravin brought to our attention in his "home theater" topic. A link to the article..
http://www.vonschweikert.com/zvr10.htm
Quote from the important part of this article: "The winner by a large margin is the Audax Professional 7" Aerogel-coned midrange driver. These rare and expensive units are hand-built in France and come with serial numbers; the Aerogel cone is a composite formed of carbon fiber, Kevlar, cellulose acetate pulp, and a ceramic binder. This cone is extremely light and thin, but does not ring due to the spongy internal composition; wave energy is absorbed, not reflected, by the random nature of the internal particles. This exotic cone is driven by an expensive edge-wound ribbon voice coil suspended in an enormously powerful magnetic field, larger than the magnet found on most 12" woofers!"
This makes this driver choice seem good to me....
As for the tweeters, I have a few prospects, but before listing therm, would like to go over some of the choices available in terms of construction types and materials used. I want very bright and sharp highs, but do not want shrill, ear pain causing stuff that will drive me nuts in the long run.
So anyway, what do you think from here??
swez on 09/22/2007 09:19:39
I think this is a good project to research for a time, learn the basics of crossover design and move from the 2-way plan in the now, to adding a 3rd driver in the future. A well matched 2-way system can be done on a moderate budget. Ash has proved this on several of his projects to date. Am sure he is more than willing and able to guide you along this path since he has been there before.
A good pair of 5-1/4" woofers can be used for both MB/MR functions. Here, if you cross them at 80 Hz., and use a quality tweeter that can handle good power at say 2,500 Hz, the audio spectrum is pretty well covered in the front stage. The sub(s) will do the rest.
Some guys use the rear speakers for MB only. That is an option if the front MR/TW's are strong enough and well amped. Unfortunately, to get adequate punch from the rear MB drivers, they will need to be amped too.
The Audax driver mentioned had a very flat frequency plot above 150 Hz. It has very stable MB/MR out to 1,500 Hz and still not bad up to 2,500 Hz. It is a 6 ohm driver though. When factoring in cabin gain, lower MB extension should be pretty good down to 80 Hz.
The mounting depth is 2-5/8" on this speaker. Chances are good you will need to make a baffle panel for the doors to get adequate clearance from the window mechanicals. (1/2" baffle plate?)
Finally, the efficiency of this driver is actually pretty good and flat between 150 - 2,500 Hz. (~87dB SPL @ 2.83 volts) The power handling is a modest 40 Wrms, so the SPL level at full power is just about 100dB @ 40 watts. (15.5 VAC) Peak SPL is more like 101 dB SPL @ 60 Watts peak. Not bad at all for this price. (19.0 VAC)
What say you?
Swez
Ash on 09/22/2007 10:29:21
There is a lot involved in making your own component set which takes quite a bit of patience, experimenting, and some form of testing & subjective evaluation.
You can wing it with a simple 2-way if sensitivity of both MR/TW are matched closely. However, in my experiences a lot of the available specs is very subjective since we are working in the auto environment. Placement is everything as we know and can make or break a design. The given frequency plots rarely give the normal off-axis listened to in the car. It will help much to use higher quality drivers to ensure low distortion and a smoother frequency plot (still no promises).
Hints:
If you are looking for a good detailed midrange to work in a 2-way, you may want to stay in the lower Q's as these normally have more a detailed smoother response although less lower mid bass. Expect real output limited to 120-200hz on the low end. Not a bad trade-off if you have a somewhat robust sub that can bridge the gap. Here you factor in cabin gain and lean (12db) x-over slopes to help.
Go with "infinite baffle" mids (Qts greater than .6) you will have to be carefull as these can often can exhibit a peaky response with a higher FS. Though they might exhibit more mid bass the response may not be as smooth and harder to blend with the sub as they are both playing in the same range. The latter may seem like a good aspect, but in reality it can insert more problems as phase and time delay become more of an issue. You do want a gap somewhat as there still will be rise in response from the sum of the two. This holds true for the MR/TW match as well in both the low and high Q drivers.
Power handling is going to be affected by three factors: thermal, usable xmax, and x-over slope. As of now I am using higher Q (.7/ tested .57 in doors) Audax mids with an xmax of 4mm. Before I had lower Q (.38) with the same throw and to be honest with you the higher Q's are more impressive if ran without a sub. I am seriously thinking about switching back for the lowers had better definition.
What it is putting out is more important than how much xmax. It will take more xmax to produce lower bass than upper bass of course, but if you don't need the lower then it is just wasted, so you can see how that can be misleading. If your'e trying to get more output in the 150-200hz range then you will have to check out the available frequency plots and see what is the driver's nature.
I won't go into enclosed drivers as that will have to be tested to ensure accuracy (perhaps with the Dayton WT3). I will tell you this, your lower Q's are your best friend as they will require way less air space.
Almost forgot another important point. Do not mistake sub bass for mid bass. You really have to train your ears to decipher the two. This is something most mistake and are never satisfied as they are "chasing a dragon". Understand that with mid bass units (especially in 3-ways) you should be only trying to supply the fundamentals of the upper bass region & lower midrange (the snap of the initial drum strike/ male vocal & so forth). Beyond that and you will introduce blending problems.
The sub takes over the rest unless you are using a steep order (18-24db) and low x-over point 50-60 and under. This is especially true if you use a box/driver alignment that will already lack any upper bass range.
This helps? Maybe not, but if you got any questions just ask.
Ash,
swez on 09/22/2007 14:53:15
Good feedback there Ash... knew you'd be adding a few pieces of this puzzle at some point. ;-)
Interesting how the Qts measured 0.7 initially and in the door, it dropped to 0.57. How did you get a to 0.38? (Sound a bit muddy there?)
Have a few Q's for you Ash... (If you have the time and tools)
1. At what frequency point does the "cabin gain factor" begin to roll off? (Am thinking it peaks above 45 Hz and begins to decay to <+3dB in the 300 Hz., range) Can you verify that with your test gear? (Off axis testing is good)
2. Also, we know that 1 MR driver will net xx SPL at say 5 watts. (RF speaker only = about 90 dB) Suppose we feed all speakers the same test tone at 5 watts each. What is the SPL # now? (RF,LF, RR & LR)
Here, Pink Noise would be a good representation of overall gain in full range speakers. If we wanted to find cabin gain nodes, or MB/MR only, then incremental test tones would be used.
Are you able to perform such a test matrix? (No subs in this test, just full range)
Swez
Ash on 09/22/2007 18:14:10
The .7 Qts was the published data. When measured in the door it was .57 (contribute that to inaccurate data). This is why it's important to be able to test if you want at least somewhat accurate results.
The lower Q was another Audax driver which happen to be right on with the published specs. Actually bass wasn't as muddy as the higher Q driver. Yes there was a lack of low mid bass, but the 100-150 range was quite decent. The Q factor is an indicator of peak at the FS and with that being said, the hi-Q driver possibly had too much peak to blend with the sub and MR. Mouthfull huh?
The USB4065's crossover is limited (12db hi pass/ 200hz @ 24db lo) and there I believe the problem lay. I'll try the low Q's again with the new AC unit with a lower setting on the high pass (70-80hz @24db) and higher point on the low pass (300hz@ 24db).
As of now I haven't been able to test actual cabin gain as I have still not settled on a RTA program. That point would be very interesting as most only consider low bass gains. I would assume without being able to detect any other peaks it would be hard to attain a smooth response unless you have an broad range EQ and a subjectively trained ear.
I'm quite sure there will be an SPL gain from more drivers, how much would be hard to say. It could be easily estimated that each added driver will net another 3db, but I don't think it actually works that way in the real world when you consider the rears are usually faded out some. Plus listening position plays a factor as well; different path lengths between ears and all drivers.
Once I stop procrastinating I should be able to measure some of the anomolies mentioned.
Ash on 09/23/2007 08:33:49
Okay Thump....
I did the switch back to the original low Q Audax drivers and of course the difference was definitely an improvement. Using the x-over points mentioned above, they integrated much better.
The high Q drivers had more snap and lower mid bass, but sounded boomy when played between the sub & MR. Less detailed with overexaggeration with certain instruments.
The low Q had a more deep punch that better matched the initial impact of the sub. Upper bass was more smoother, yet not as anemic as one would think. 1 db lifts in the 120 to 180 range on the EQ gave it the presence needed to add to the MR.
My setup consists of active filtering with passives only between the small 4" MR & TW. If you are going to try building even a 2 way, I suggest you use an active crossover as this will take out the guess work and give you better matching capabilities. This will require the use of a 4 channel amp as MB/MR will need their own channel as well as the TW. Later you could easily convert it to 3-way by using passives between the MR/TW.
As for power handling, that depends on what the sensitivity and usable range that each driver will play in. I would say a minimum xmax of 4mm for mid bass driver to get decent output for low Q. Since mid to high Q's present more output in the FS region you may be able to get away with less throw.
Don't expect it to be dirt cheap. However, you will be able to attain a high quality/ audiophile setup for far less than you could buy one already built. The use of home audio is your best friend here too.
Here are some brands to check out for both MB/TW units:
Seas, Dayton, Audax, Peerless, Aurum Cantus, HiVi Research, TangBand, Vifa, Mach 5, etc..
SQLThump on 09/24/2007 02:24:29
Thanks for the great responses guys! Ash, your input is greatly appreciated knowing your prior expeirence with DIY components.
First, responses to you fellow's replies
Before I go any further I would like to state a few things. I do want to use the stock speaker locations at the top of the dash to keep the mids and tweets close together, and to maintain the "In Yo Face" imaging they provide. There is optimal space in the dash to give just about any neccassary airspace for a small enclosure.
Also, the speakers will upfire towards the windsheild, and possibly prevent beaming from the tweeters, and adds ambience that with even my current speakers makes the soundstage seem larger than it really is.
The doors are a different story. There is no place to mount any sizeable driver without some MAJOR door panel modifications, as there is no large, flat surfaces. I also want all of the music to come from the front, and would definitely like to refrain from using midbass drivers to the rear of the driving position.
I do plan to cover the upper bass lower midbass with a smaller sealed sub setup as opposed to using dedicated midbass drivers, so I think a nice set of 5 1/4 should be able to cover the frequencies above that. I will go over what crossover points I would like to use towards the later in this post.
Bi-amping is something I want to avoid, and I want to gain the expeirence from building my own crossover networks. I did go through the read you provided Swez, and I think I can get this figured out with decent results. Plus, buying a new 4 channel, a decent active crossover, and another set of Monster's to wire it all up would rack up quite a budget.
In terms of measurement, I really don't have anything to measure it with besides by ear, comparing it to a few buddies that have systems in their cars (namely my nieghbors FoCal comps he has in his Durango) and a good selection of different speakers to compare by ear in the car audio shop he manages. As far as test equipment goes though, nothing is available at all.
My goal here is to more or less to make a decent pair of listening speakers, with decently flat response, and most importantly, have fun doing so. But going for the perfect no dips or peaks greater than +/- 1db is definitely a bit beyond my ability.
And now, some of the homework I have done.
I looked at a few different drivers, but I am still liking the idea of the Audax AP130Z0 5-1/4. Their Qes (this is the right spec correct?) is at .57, which is the same as the in car high Q midbass driver correct? What size drivers are you using here? Would one be able to count on a slight drop in Q rating when installed?
I took into consideration matching up power handling and sensitivities on both drivers as closely as possible, and thought HiVi had a nice offering that could fit the bill well. It is rated at 40 watts, has 88db@2.83v sensitivity, and would match the Audax well at 6 ohms
HiVi TN28 Fabric Dome Tweeter
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-409
Just for easy reference, paired up with Audax AP130Z0 5-1/4" Shielded Aerogel Midbass drivers for the midbass.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-155
After readind the link Swez provided, I put the calculator on there to use and came up with cap. and inductor values for a 2500hz crossover point at 6 ohms. Here they are:
HP cap.: 5.31 Microfarad
HP coil: .76 millihenrie
LP Cap: 5.3Microfarad
LP coil: .76 Millihenrie
I am looking along at some of the different rolloff graphs and am of course noticing that they all have a dip aroung the crossover point. Would I want to cause a delay here or create some sort of overlap to compensate so there isnt a hole in the frequencies? If so, how big would I want to make this?
Thanks for all the help guys. Ash, thanks especially for measuring the differnet drivers for this purpose too. This is the "above and beyond service" that makes this best site around!
swez on 09/24/2007 07:40:07
Thump,
Cleaned up the duplicate posts and will address the drivers noted and your Cap and Coil values now.
Since these are 6 ohm drivers and both drivers have a good range crossover point at 2,000 Hz., (2.0KHz) that looks like a reasonable place to start. As I ran some numbers, it looks like you may have some adjusting to do, to find off the shelf parts to build your crossovers. Here are the initial values I came up with for both HP and LP filters:
http://www.bcae1.com/passxovr.htm
HPF:
Cap1 = 13.26 uF (C1)
Coil 2 = 0.48 mH (L1)
Load = 6.0 Ohms
LPF:
Cap 2 = 13.26 uF (C2)
Coil 2 = 0.48 mH (L2)
Load = 6.0 Ohms
The schematic diagram will look like the link below when wired: Just subtitute the new Cap and Coil values to compensate for 6 ohm drivers. Also note the TW is wired out of phase to the woofer to compensate for a 12dB/oct filtering network.
http://www.partsexpress.com/pdf/260-142s.pdf
The next step is the fun part... finding a combination of caps/coils to get the desired target values. Here, the Cap will need to be a non-polarized type and rated at 30 volts or higher. Here are some off the shelf products from PE that can be used:
C1 & C2: http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=027-342
(12.0 uF)
L1 & L2: http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-408&DID=7
(0.47 mH)
The Caps are of fixed value and 12.0 uF is well within tolerance of the targeted 12.06 uF. Use as is.
The Coils have a slightly higher value then projected, but the value can be changed by removing a few turns of these coils and then burnish the insulation and tin with solder to install. This coil is w/i the +/-10% tolerance range too. Ca be used as is.
A prefab PC board for 2-way crossovers can be used and save a lot of time:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-120
Your layout of components, (C1, L1, C2 & L2) are listed in this diagram:
http://www.partsexpress.com/tech/260-120.html
OK, this package seems to add up very well to the targets mentioned earlier. When we consider the tolerance factor of +/-10%, each component fits as is. If you want a closer tolerance value, the cost of the parts are much higher. (Adjusting your own inductor coils is an option)
Ran some additional calulations with the components noted above. The C1 & C2 values of 12.0 uF and L1 & L2 values of 0.43 mH will net a crossover point of 2,200 Hz., for a 6 ohm speaker. That is very good for the 2 drivers mentioned in your selection. (Pretty darn close I must say)
How's that hit you now?
Swez
Ash on 09/24/2007 08:55:21
The Qts should not change once installed in the door or whatever. Running infinite baffle in the doors is essentially a sealed box and regardless how big the space, the Qtc will not go below the driver Qts. This is why you choose a driver by it's Q, but not soley.
The question is how accurate is the company's measure. I bought a driver that was published at .7, but when tested it was .57. That could have been okay if the Fs was below 70hz. Keep in my mind that the response was for my vehicle and different cabin gains/ transfer functions will result in otherwise. A little hard to explain but if you can check out the measured frequency plots, you will see the difference.
A good site to see this is CDT. They have a link that let's you check out all of their mid bass specs and shows door installation and box plots. There you can see what I'm talking about as I might not be explaining this good. You will have to click on individual drivers to see the specs and plots. Pay close attention to the Qts and Fs of each driver as you notice the change in response.
http://www.cdtaudio.com/midbass_drivers.htm
Depending on how much mid bass you want, a 5.25" is only good for 2-way as it will not add much to the low end. If you want to cover a broader range or use a 3-way, it is almost imperative a 6" or bigger is utilized. I believe Tangband makes a very high throw 5.25", yet I don't think it's all that efficient enough to use passively. Goldwood makes one specifically for auto use that might be of interest.
SQLThump on 09/24/2007 13:52:50
Again, thanks for the responses. My computer is still acting screwy, so I can't chack any of the posted links. I will get back to you guys later tonight.....
swez on 09/24/2007 14:10:52
That CDT link is most helpful and the plots change a good deal based on the Qts, Fs and F3 numbers. (CL-5 & CL-50) I see what you mean and the only real way to compensate for the lack of lows is to port the speakers. (But now, we get a camel's hump effect as well) The plots above 100 Hz., are very good. But below that point, too much roll off. (The "in car" performance MB of these speakers is not all that impressive from past experience either) :-(
Looking at the Audax driver, the Qts is 0.41 and Fs is 57.6 Hz. However, the Vas is notably larger than either CDT speaker too. Note the usable range on the Audax as its F3 is more like 150 Hz. That tells me the Audax is an extended Midrange speaker, more than a Woofer or Midbass driver. (A fair MR, but not exceptional above 2.5KHz and below 150 Hz.)
Comments?
Swez
Ash on 09/24/2007 23:50:21
Exactly... Interesting how that works. You really shouldn't look at an mid bass unit like one would choose a infinite baffle sub.
The easiest way to skip around all this is to build some form of enclosure. With that you can better control the drivers output and put it where you want. My theory on that is to use the "solobaric" type setup (essentially low Q drivers meant for ported boxes, but with enough throw to take a sealed). That's another story.......
Thump, I seriously hope I'm not confusing nor dissuading you. There is just a lot of aspects to building from raw drivers which can become expensive if just doing guess work. Sometimes it is better to learn from others trials & mistakes than to waste ones own time & resources in something already proven.
For now I'll let all of this sink in and give you thought as what direction to take.
Ash,
swez on 09/25/2007 21:55:49
Well said "O Learned One" !!!
Remember our guy "Lessismore"? He said the same things and we are now believer's in the same basic fact... "Simplicity, is a virtue we can all strive to master". (K.I. S.S. is a great acronym to motto ... Keep It Simple Sam)
After looking at several offerings from PE, I noted there were trade offs to contend with in most every option in their 5-1/4" drivers. Some were poor low end response. Others were good midrange extension. But the driver's that did both well, cost a lot more too.
Also, to follow Ash's train of thought, enclosing speakers can help a lot when we understand the basic parameters of a given speaker and know how to minimize deficiencies and optimize the given traits of a specific driver. That knowledge does not come overnight and many will use trial and error at great expense and wasted time to prove their lack of understanding. (Don't become one of them unless a fat wallet allows it) hehe
Finally, a larger driver, (6" or more) can be a very good solution to this dilemma. Yes, some metal cutting or making fiberglass door pods may be needed to make that happen, but a solid 2-way system has many benefits if the design parameters are well understood. There are many good MB/MR drivers in the 6.5" range that would do very well here. It just takes the knowledge and patience to find them and fabricate as needed for the best results.
Swez
SQLThump on 10/6/2007 00:51:57
Sincere apologies on the long response time. Every time I log on, browse a few new posts, come to write on this, lose my connection and post, throw brick at computer, repair it, try again.............
First, I see where we are getting with this and was wondering if the gap between say 80-150hz was covered by an "upper bass" driver, as oppossed a dedicated midrange. This is something I have been thinking about for a long time, and would rather put a pair of 8's in an easy spot to put an enclosure (under or behind the seats) rather than go to cutting or building things.
I understand that this could be a "boomier" way to go about doing this, but I am fine with that. With my listening tastes, I prefer to have my insturmental (drums, bass guitar) to sound like boomy bass anyway, so this is something I would actually like. I love bass heavy music, so this would probably give me the optimum blend of "SQL vs. Thump" I do understand you can't have it all, thats why I want to design my whole rig myself, rather than deal with how Infinity or Alpine thinks my music should sound, because thats about my budget limit on this project.
Second, I guess i should have been more clear on the goal of this project. I was looking to try to build a set of comps for the price of some stout coaxials. I would rather not go the coaxial prefab way of things, but I don't want to go over the top with this project. Swez, I am sure you know the woes of working with an older Buick when designing a system, namely the one that the car hardly justifies the means. But, I will be driving this car for another year or so, and probably a lot after I get a "project car" and would like to make some improvements over the ghetto rig I currently have setup.
That being said, cutting doors and doing my first fiberglass job on my car could have a good chance of disaster, and this would be a hell of a punishment to a good running car that already has major visual flaws. It's just more time and energy than the car is worth. I could keep a more reasonable budget and save a few headaches by finding a nice coax setup. I would like to keep it on a simple daily driver status, but with some healthy sound and overall performance.
I am pretty sure that using upper bass drivers with this setup of speakers would probably help me acheive my goal of the ultimate low budget rap system. I seroiusly do not want to spend more than around $100 for for a new front stage, and would rather not buy a new upper range amp. if all else fails, it may be the Infinity's or the Type R's for me........
swez on 10/6/2007 11:15:51
Quote: "wondering if the gap between say 80-150hz was covered by an "upper bass" driver, as oppossed a dedicated midrange."
This depends on the midrange speaker used. Many 5-1/4" drivers can handle 80 - 5,000 Hz. signals, but the SPL level at the low end of this spectrum is often several dB down from what it can produce at say 1,000 Hz.
Knowing the frequency plots of a given driver are very helpful here. We also get the benefits of "Cabin Gain Effect" in the MB region, but that depends on the vehicle and installation location/techniques used. "Midbass" is the range between the sub and Midrange speakers used. (Typically 60 - 300 Hz., or 2-1/3 octaves) 6.5" and larger drivers are generally most suited for this range.
I get your point on investing a huge amount of time and money on an older car. (Have the same issues too) In this case, getting the most from what you have now is sensible plan. (It's hard to make a silk purse from a sow's ear)
As you mentioned, adding a pair of MB drivers in an enclosure and tooling it to fit in the rear doors or back seat foot wells does make sense. That can be done with careful planning and using MDF as your enclosure material to keep it low cost. (The trick is to protect the speakers from "damage and grit" from rear passengers feet)
The issue still remains about amping these speakers and a bandpass crossover network that makes sense. This could be done, using the rear amp channels along with your rear deck speakers. (Net 2 ohm load to your rear channels) Here, a "Tri-mode configuration" may also be considered, if the amp can be used that way. (Most can, but MB speaker ohmic loads must be taken into account... 8 ohm MB drivers in parallel, but MONO signal)
Finally, some coaxial speakers now come with removable tweeters. They are basically Component speakers, (External crossovers and phase plugs) that can be used as Coaxials or Comps, depending on the application. These are generally more high end speakers and worth the investment as they can be used in your next ride as Comps.
Swez
PS Chew on this one a while and then come back with your thoughts. If this were my project, I'd make it flexible in design and easily transferred to the next vehicle. Chances are that you can gut this car and sell it for dirt cheap as transportation, (W/o audio gear) spare parts or send it to a boneyard.
SQLThump on 10/6/2007 22:22:20
Doh! The quote was supposed to read "wondering if the gap between say 80-150hz was covered by an "upper bass" driver, as oppossed a dedicated MIDBASS."
So far, I am really liking where this project has been going and would like to use the Audax and HiVi combo. I have thought about doing coaxials, components detachable coaxials very seroiusly, but don't think it enough of a challenge, and much prefer the idea of a set of speakers custom tailored to my tastes.
Although, especially with the detachable comps, there is more to play with and tune and have fun with the learning process, at this point, it seems a little too much "connect wire A to terminal B, tighten screws, jam out" which I can get with my stereo now, and by other means. I want something to exersize my mind, my steady soldering hand, and after some hard work, be able to sit back and feel I have truly accomplished something.
I do have a decent system now, but after a year of improving it piece by piece, it has pretty much gotten to the point where everything but the upper range amp, H/U, and the wiring has to go.
I do plan on having this car for a REALLY long time, as it has been in the family since brand new, and I already am kicking myself for losing one car that was in the same boat. Plus, it has always been a great car in terms of sheer reliablilty (never really left me stranded), so I would like to turn it into the "upscale winter beater mobile" while I go insane on a nice "weekend-summer head turner"
Put some more work into the project last night and came up with some solid ideas for a good bass engine to go with the comps we came up with here. It's a bit unorthodox, but I think it will suit my tastes perfectly.
JBL Grand Touring Series GTO75.4 II
http://www.crutchfield.com/S-3XhvyQndXUw/App/Product/Item/Main.aspx?g=120&i=109GTO754&tp=115
I am already in love with this amp, hearng it pound out on a pair of Alpine Type E's in my buddies soundroom. Since he is the manager of the shop, I could score this at a deep discount, and it's class A/B technology I would prefer over an expensive, nonflexible Class D unit of similar power. Plus, in the odd case I did sell the car, this could make a great upper range amp in the future. On top of all this It would pair up nicely with the JBL LCA75.2 amp I am using for my upper range speakers, and plan to retain for the new comps. I great blend of old and new school technology.
HiVi M8N 8" Aluminum/Magnesium Woofer
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-446
I think for the upper bass drivers, these Hivi woofers will rock if crossed over around 50-60hz up to15o-200hz to phase in nicely with the Audax, and to be able to be powered by plenty of super clean amp power by the projected JBL amp.
I would get a pair of Fmods to compose the high pass element of the bandpass crossover, and then use the the variable crossovers in the GTO75.4 to find a good spot to phase in to the Audax's response, and vice versa with the LCA75.2
For an enclosure, I was thinking of something that would actually downfire into the rear footwells, again, as more of an "upper bass subwoofer" as opposed to a dedicated MB design. This would give me the bass heaviness I would desire, avoid any focused sound from the rear which I can't stand any more of late, and keep anybody's "Size 12's" (hehe, maybe we all have the same shoe size..) from deoing any damage to my treasured musical devices.
I got this inspiration from CplKittle's Kia, as he uses the 12's from 70 and below, and phases in the 10 at 70-200. Kit, if you've been following, am I correct?
Considering the other drivers, and their combined power, this should be able to work at providing me with the ability to enjoy detailed, level sound at a lower subwoofer knob setting, then be able to whip out the "this is way too loud" bass with a few minor adjustments.
I have been thinking about doing something like this for months, and I would use the Front RCA output to the upper range amp, and from there use the rear and subwoofer outputs to the bass amp, and use the A/B channels connected to the rear output to power the HiVi's, and then use the C/D channels with the sub outs to power a currently nameless subwoofer.
In terms of the lower end subwoofer, I am not too sure here, but I would definitely want something that will cover from nearly subsonic to around again, 50-80hz, with emphasis on the really low notes. Here I can sacrifice some accuracy, I just want as much of a 30hz earthquake as capable with the power allocated to the bass engine.
Problem is, I really don't know what brand of subwoofer to turn to for this really low bass, considering the power available. I am pretty confident that the usual subs I would turn to would to (Diamond D3, Infinity Reference, Alpine Type E) wouldn't be geared enough to said super low notes. Here, I am willing to spare no expense to find the perfect sub to rock the house, errr...automobile.
Considering the low range of frequencies it would have to cover, and the upper bass drivers there specifically for upper bass, I would want something capable of running in a bandpass enclosure tuned to an insanely low point.........
Time to find this sub and put it on a hit list. Would I want to look for a more SQ or SPL aligned sub driver though? I am truly clueless on this idea, as I would want it geared for insanely low bass. Is this where I start looking at brands like CDT, Focal, ect?
I will do some more research in the sub department, but it is on the last of the list in terms of priority. I just really want to get rid of them damned 20W Alpine coaxials..........
SQLThump on 10/6/2007 23:09:24
Well, I think I have found an ideal sub to pair up with this whole rig.
http://www.cdtaudio.com/pdf/EF-120%20specs_parameters.pdf
Looking at the frequency plots at this CDT EF-120 for a 1.5 cube sealed box, it seems like the perfect driver to match the plot of the HiVi M8N 8 inchers.
Coments?
swez on 10/7/2007 08:40:32
Mind doing and "Executive Summary" of the amps and speaker pairings?
General comments:
After looking at this new plan and such, The HiVi's noted would be a very good choice as Midbass drivers. They are very strong in the MB region and can handle good power too. The best amp to power them, seems to be the older JBL LC amp, bridged MONO and a bandpass filter network.
The GTO 75.4 is great for powering front comps and a 4 ohm Sub off the rear channels. This is a great amp and plenty of reserve power too.
As for powering the rear speakers, those Alpine's mentioned would be good enough for the rear fill and powered off the HU. (They are just that... rear fill)
About the sub, this CDT or the Infinity Ref 1250W would be a good options. The Ref is much cheaper and well suited for sealed, ported or BP. (Would not recommend BP here... poor SQ at the expense of a bit more SPL) The Ref 1250W will go low in sealed or ported box designs. Here, sealed makes a lot of sense:
http://www.crutchfield.com/S-lBHggv9aVXV/App/Product/Item/Main.aspx?g=520&i=1081250W&tp=111
Comments?
Swez
SQLThump on 10/10/2007 01:56:36
Executive summary... huh?
Ok here it goes....
Midrange: Audax AP130Z0 5-1/4" Shielded Aerogel Midbass
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-155
Tweeter: HiVi TN28 Fabric Dome Tweeter
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-409
Crossover parts for seperating the above listed:
C1 & C2: http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=027-342
(12.0 uF)
L1 & L2: http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-408&DID=7
(0.47 mH)
Circuit board:http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-120
Midbass: HiVi M8N 8" Aluminum/Magnesium Woofer
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-446
Amps: JBL LC-A752
http://ampguts.realmofexcursion.com/JBL_LC-A752/
JBL Grand Touring Series GTO75.4 II
http://www.crutchfield.com/S-3XhvyQndXUw/App/Product/Item/Main.aspx?g=120&i=109GTO754&tp=115
As for the sub I am still undecided. Looking at the out of car plot for the 1250W, and at that for the CDT, wouldn't the CDT feel a little more at home in the extremes bottom octave than the Reference?
I understand cabin gain will work in the favor of the Reference to hit the notes, but the CDT looks like it will be already dumping those super low notes out before it even comes near my car. I really want the super low notes to come out as hard as possible, and if the CDT will offer me that much more performance, I am more than willing to fork out the extra money. Here are the links for the manuals for both drivers.
CDT EF-120
http://www.cdtaudio.com/pdf/EF-120%20specs_parameters.pdf
Infinity 1250W
http://manuals.harman.com/INF/CAR/Boxes%20and%20Parameters/1250W.pdf
Tell me what you think here. If it's not much of a difference, I would be willing to go for the Reference. I have used it before, with the old JBL LC, in a BP box, and it did nicely, but the super low performance was kind of lacking. Also heard a pair of them in a freind's Camry, in the sealed enclosure, and again, kind of the same thing. That's why I was thinking a different driver, and probably need to think on this some more.
As for using the JBL LC for the midbass, thats a good idea I had not thought of, and will try when I get the whole setup. The amp is damaged though, and will overload when recieving too much low frequency input, but works like a champ for highs and mids. Can't hurt to try, so when everything comes in I will check this out. Definitely hopes this works, because It will be much easier to power up the 6 ohm comps properly with the GTO amp. Good thinkin man!
As for the bandpass filter, I was thinking of using the variable crossover on whatever amp ends up being used for the midbass drivers high pass, and using a Harrison Labs Fmod setup for the low pass section.
A link to this Fmod
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=266-256
Well alrighty then, I'm going to bed. Tell me what you think guys......
Ash on 10/10/2007 20:57:06
The simplest and in the end most economical & versatile way to do this is an external active x-over. There are several on the market that aren't really that expensive and have way more points to choose from than what you are opting for.
Depending on the amps internal x-over may limit you to what I have experienced before (undesirable frequency slopes and cutoff points). Is better to get a unit specifically designed for that use.
This can go a long way as you find yourself experimenting with different drivers, you won't have to keep changing amps or filters.
SQLThump on 10/11/2007 02:23:11
I thought about this too, and the idea is a bit out of budget for the project. Plus, I really don't plan to play with too many drivers for this car, as this will just be my daily bucket, and I plan to buy a new "project car" to really spend the dough on. Buying a crossover, and getting a new set of RCA's (god, quality cables are expensive!!!!) to set it up with is just a bit out of reach.
The crossovers on the JBL are pretty flexible, and I do plan to buy an older Alpine H/U with the EQ, crossover, 5V preouts, MP3/ WMA and all the bells and whistles as soon as one crosses my path. The search has been long, but I will find one!
Swez, in response to the using the old Alpines for rear fill, I do not plan to use them. My H/U makes much better sub output when the internal power is turned off, and I am using the old 6x9 holes for cabin ventilation from the trunk. I really don't like using rear fill much anyway, backseat passengers can just deal with it! GRIN
swez on 10/13/2007 21:07:12
Got it and that makes sense too. Front Comps w/ MB added would be nice in this setup.
Active Filters are nice, but the F-Mods act like Active filters as they are used at the input side of the amp and not passives on the speakers. The 12dB slopes are gentle enough to give a nice overlap too. If your HU has variable crossover points, that's even better than fixed filters like the F-Mod option.
Also, not using the HU amps, (defeated) gives a better quality signal to the RCA outs. This is true of most HU's that offer that feature.
Will look more closely at your details tomorrow as I am now pooping out after a very long week at work. This seems to be coming together very well, but a few double checks are in order before taking the next step.
Swez ZZZZZZ Good night to all
SQLThump on 10/14/2007 04:32:57
COFFEE My thoughts exactly. Sleep good man.
swez on 10/14/2007 12:07:11
OK, lets have a look at your details. I slept very well last night and ready to rock!
1. Crossover board (Good, if you want that option/expense)
2. Midrange: Audax 5-1/4" (Good between 300 - 2.5 KHz.) 6 ohms
3. Tweeters: HiVi (Good at 2.5 KHz to 20 KHz) 6 ohms
4. MB: HiVi M8N 8" (Good at 70 - 300 Hz) 8 ohms
5. Sub: That's a toss up... either sub noted is good. The key factor here is the right size box and placement of the box in your trunk. (Firing to the rear bumper, ported or sealed) [70 Hz., LPF]
Note: The MB drivers are solid when paired with the JBL LC-A752. This amp can be bridged MONO and the MB drivers wired in parallel for a net 4 ohms... a solid match. MB drivers are like woofers and can be used on a MONO channel. They are "Omni-directional" in nature and cabin gain will help the low end.
The LC-A752 amp has a selectable variable HP/LP filter. (32-320 Hz) Here, use the LPF function and set that to about 300 Hz. This cuts off the highs. Manual:
http://manuals.harman.com/JBL/CAR/Owner%27s%20Manual/LCA752%20om.pdf
Use F-Mod HPF, 70 Hz. as the bass blocking filter and use the amp LPF set at 300 Hz., and you'll have a nice active BP filter for the MB drivers: (Easy deal huh?) CLAP
http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=266-272
====================================================
Now comes the fun part... the front stage amp and crossovers.
The GTO75.4 II has good active HP/LP filters and we'll use the front channel HPF's, set at 300 Hz. This will block the lows to your 5.25" Audax MR. The HiVI MB drivers will be 70-300 Hz. The only thing you'll need here are passive HPF's for the tweeters. The target here is about 2.5 KHz. Since we have a 6 ohm tweeters and Mids. The proper Caps/Coils for a -12dB/oct filter are as followed:
Caps for 6 ohm speaker, HPF @ 300 Hz. = 44.2uF
This is not a standard value, so we'll have to come close. This is 47.0 uF and will do nicely:
http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=027-352
Another option is three 15 uF caps in parallel. That nets 45uF, if you have the space: (These are cheap if space is not a problem)
http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=027-344
Coil value here is 6.4 mH's. Lets see what we can find that comes close: Ahhh... 6.0 mH's is close enough:
http://www.partsexpress.com/pe/showdetl.cfm?DID=7&PartNumber=255-286
You can mount them on the noted prefab circuit board or wire them loose and then bundle them with hot glue and seal them with epoxy based paint against moisture. Either is good nuff.
FYI: Not sure how you arrived at the C1/L2 values but I used BCAE1 to calculate the values:
http://www.bcae1.com/xoorder.htm
Tech Tip: Most tweets need to be wired out of phase, (Reverse Polaity) with the Midrange when using -12dB passive filters. You may have to experiment to determine what sounds best in your ride.
Also, most passives have a tolerance factor variation of between 2-10% of target values. The tighter the tolerances, the more they will cost.
Whew... I gotta stop for now. Review the notes here, do some calculations if you like and we'll try to wrap up your parts list this weekend. This stuff fries the brain after a while huh?
Swez
SQLThump on 10/16/2007 18:16:44
Alright, I think this is all coming together then.
I originally came up with those C1/L2 values from the earlier post you left on the crossover parts needed. That point was 2khz, if I read properly. Either way, thanks for the redirection on the parts, and I'm extra glad I didn't order them last weekend.
Wait a second, I just got a little confused.
"Caps for 6 ohm speaker, HPF @ 300 Hz. = 44.2uF
This is not a standard value, so we'll have to come close. This is 47.0 uF and will do nicely:"
Considering we will be using the crossover on the amp, will we need a HPF at 300hz? I thought we would just need HP and LP at 2.5Khz.
I am considering just dropping the circuit board, and maybe building a slick looking set of crossover cases that could look like something Focal or Diamond would offer. I got more than enough plexiglass, plastic, old amps to part out for terminals and glue laying around to have enough to build a production line of components. I saw this spiffy little link on PE showing a really ghetto way to put together a crossover.
http://www.partsexpress.com/resources/building-a-crossover.cfm
Hey this guy put together something more ghetto than me, so I am sure I could make something wicked cool to show off my work on these comps.
As for the sub, I think I will try the Reference series first. They are some pretty decent subs, I just hope than can dump out the super low bass I demand. I will probably build a sealed box first, due to simplicity, and from there try ported then bandpass if nothing before it yeilds my "bass-head" requirements.
I was also thinking of using some lower crossover points for the lower end of the scale here. Would the Audax be severly impaired if used under 300hz and crossed over around 150-200hz?
Also, I was thinking a bit lower of a crossover freqency to cross over the sub and midbass, to where the 12" acts as a superdeep bass driver, so notes in the 30hz region are as powerful as possible, and the 8's provide really tight, contolled upper bass. I really like my music boomy, and if I can't make certain sounds thump right, I would kind of feel like a purpose was defeated.
I am more than willing to compromise a midbass fidelity for an increase in low end dumpage.
I dunno, but right now, my brain is also a little fried. It's been a long day at work, and I need a nap.
swez on 10/17/2007 05:30:14
Hehe, working all day/night will do that alright!
Yes, the crossover points can be shifted if you wish. (To a point) Here's a general outline to consider:
Sub: 35 - 70 Hz. (Sealed, Ported or BP) Low bass only
MB: 70 ~ 200-ish Hz. (The gut punchy bass part)
MR: 200-ish to 2,500 Hz. (Good power handling this way)
TW: 2,500 Hz and up
This will also mean changing the coil and cap values we looked at earlier. The F-Mod choice is limited to 50 or 70 Hz.
FYI: There is very little bass content in most music below 35 Hz. It takes a lot of power, sub cone area and a well designed enclosure to beef up that range in a subwoofer system. In Pro installs, we use 15's and 18" subs and several thousand watts RMS to get the SPL numbers to desired levels. (But this is large venue gear too)
In a car, we have to scale the sub(s) and amping power to fit the vehicle. Strong bass in a 300 ft^3 listening space, (Trunk and cabin area) is a challenge. Most use raw amping power and large cone area subs to get there.
In a larger vehicle like an SUV, Van or similar ride, we have a lot more airspace to work with and easier to get more cabin gain from them. Here, a modest amp and efficient sub designs can give very nice bass.
Swez COFFEE
SQLThump on 10/17/2007 16:26:12
Those crossover points were a little more in line with what I was thinking here.
As for the subject of superdeep bass, I am not sure of the true extent of the Hz cycle, but I have plenty of music that hits so low that I have only heard a handful of bass engines capable of even coming close to reproducing these frequencies. I would offer to send a couple of songs over to demonstrate, and get your opinion on the Hz that the bass is hitting, but all of it would probably be "a bit" offensive for your tastes.
As for making these notes pop, I think that 300RMS to a sub will do me plenty. I have never run that much power to a single sub before, and I have had a couple of systems that could do it. Also I have never run anything larger than a 10" sub that wasn't some form of house speaker. I am confident that if I follow the rules, laws and other practices, that I can get these notes to pop better than any of the ghetto crap I have used in the past.
As far as cone area goes, that is the reason I am going to check out a 12" sub instead of my usually favored 10". I looked into a few options for 15" inch subs within the wattage range, and really couldn't come up with anything I would like to use, or that would work well with the power I want to run.
I am also willing to go with a pair of lower powered subs if that is another effective way to get the cone area up in the higher square inches. The only sub I have really found that people make anymore in the 150W range are Rockford with their pathetic Punch Stage 1.
I am more than willing to go with a bigger/more subs sub if I can find one that will work well With the JBL GTO 75.4 amp I want to use. The one thing I really don't want to go bigger on is amp power.
As far as enclosure choice goes, at this point I am willing to try any of the craziest options a person can try to make the lower bass stand out in a midsize sedan. I really don't care what I have to do, and I will give up ANY trunkspace or cabin room neccassary to acheive such a goal. Show me some stuff, help me design it, and I will build it!
swez on 10/17/2007 19:42:33
The GTO bridged nets out at just under 300 RMS @ 4ohms. That's a solid place to be for the Infinity 1250w is a good match and a port tuned box, (30-35 Hz.,) offers a good low end bump. Unfortunately, Infinity does not publish their frequency plots. If they did, we'd have a better handle on what to expect in the lo-lo stuff.
Have heard some music cuts that have a lot of deep bass tracks and yes, they may go down to about 36 Hz. But this takes a good deal of amp power a larger format sub to get there.
Porting this 1250w is a good option, but sonic quality will suffer a little below 40 Hz with this sub. It needs a 2.0 ft^3 chamber, a 4.0" round port of 12" long will give a PTF of 36 Hz. That's not bad at all.
Swez
Ash on 10/19/2007 00:54:29
It would be beneficial to know exactly or at least close to what your vehicles corner frequency is. If you could do that you would be better able to plot out the sub you want to use.
It is almost unbelievable how easy a sub system will wind up being hit or miss mostly because of that factor, and less of how good or bad the sub is labeled to be. Go with a F3 rolloff too high (tight) above that point and low end will suffer. Go too low (loose), the bass will get muddy with normal music and may even exhibit a one note bass sound.
Your vehicles particular transfer function should play a major role in what sub you decide to use and how you want it to sound. This is very true since most sealed car audio subs are placed in a narrow range of Q's (Qtc= .8 - .9), yet rolloff frequencies can vary much.
As for ported, you try to get the one that digs down into the mid 30's and equalize peaks in the corner frequency range.
In that aspect, there are a lot subs in the 250 to 300 range that should suffice. You might just have to work them through WIN ISD or of the like to see what they are going to do.
SQLThump on 10/23/2007 18:38:39
Ash, how does one go about finding out a vehicles corner frequency? For the sake of having a killer system, I would be willing to do any and all reasearch neccessary. Do you go to like a car audio shop to have this done? Also, how exactly would you match the rolloff to the corner frequency properly?
And I think I am failing to understand the Q factor on the drivers. can one of you fellows explain to me what numbers are important, and how it affects a driver, and works for/ against cabin gain?
So here is where the project sits right now. I am more than likely going to order the speakers and crossover parts in about two weeks, assemble them, and go with the original plan of replacing my front speakers. Afterwards, in about another 6-8 weeks, I will buy the bass engine. I can get the JBL amp for a nice score of $150, and will have to fork another 2-300 or so on the low frequency drivers.
I am definitely going to shop around more for a sub, and research more on how cabin gain will affect the 200hz and under region before picking one out. I will be getting my computer that I can put WIN ISD on soon, and will also use it to design a nice box to go with it.
I would definitly like to go with something with more cone area, and PartsExpress had this tucked away that I didn't see for too long.....
Dayton DCS450-4 Classic 18" Subwoofer 4 Ohm
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-475
Wow, this is one big lookin' speaker Vern! It is within the alloted wattage, (300 RMS) great sensitivity (94db@2.83v), definitely conservative on the wallet (under $100), is a 4 ohm subwoofer and has raw cone area. Looks like it is a new product, as it has no frequency plots available and only has one review that is a little hard to take seriously. When I get my computer back up, I will expeirment with Win Isd and runs some different sub's specs through and check that out.
Ash on 10/23/2007 23:40:19
There is a simple method if there isn't a shop willing or able to measure your cars transfer function.
Using a simple SPL/DB meter and a test tone cd you measure the response (20-150hz) of a speaker (sub preferably) outside in an open field type area. Write down the frequencies played along with their corresponding output on the meter. You'll want to do this with no type of boost or cut, just a flat input.
Now put the same speaker in your auto and repeat the same test with recorded readings. You should see a difference in certain frequencies wether peaked or dipped. You should also notice how the lower end will have a rise (say maybe around 50-60hz) and continuing into the lower register.
There you will be able to tell where your car is starting to add a natural boost. Repeat if necessary to get consistent & accurate results.
As far as Q is concerned, it is just a way of describing the tonal quality that a relative size box/sub produce. More into that later....
That sub will require a very large enclosure and I doubt it will withstand the auto environment as it is really meant for home audio replacement. Another good replacement is this one for a large sub:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-560
Power is right up your alley and enclosure size is small. The rolloff (41hz) and Q (.707) are just right for extended lows. Might could go a bit smaller on the box if you wanted. Check the project link.
SQLThump on 10/24/2007 02:06:27
Ok, finding a shop to do this is going to be next to impossible, but with a little more in depth instruction, I am sure I can do this myself since my stepdad has a DB meter for setting up fire alarms...
Ok, so will any speaker do here? All I have available is junker crap, but if that will work, I will do this very soon. Also, do I want to measure the output at a distance comparable to the distance of the sub to the listening area, or get right up to the cone? One more, do I want to do this at full power, or at a low wattage?
That being said, I will do this ASAP, as long as I know the procedure, and after this, I am sure we can take some of the guesswork out of picking out a sub. Thanks for the info man! killer stuff!
swez on 10/24/2007 02:53:10
That Quatro 15 looks like a solid driver for the power you are working with. Also, the sealed and ported box space is tolerable to most trunk mounted sedan apps.
Ash is spot on with his recommendations on testing the woofer response parameters. Just test the SPL at various frequencies at about the same distance from the woofer cone. (36 - 40" away is good) One does not need to make this test at high SPL levels either. (95 - 100dB is plenty)
Here, one is testing the near field response of the sub/enclosure in an open air environ, then load it into the car and repeat the test again at same power levels and record both results as before. I would expect to see several dB more SPL in the car above 45 Hz and then tail off a tad at 100 Hz. (8-10dB SPL more gain in the car)
That SPL meter mentioned may not work well at low frequencies. There's only one way to find out though... try it and see.
Swez
Ash on 10/24/2007 04:58:31
Exactly......
This simple test method makes it easy to know already what your car will do to a particular subwoofer and how to adjust for it.
You might want ot check out radio shack for a meter. Wallyworld now sells one (Scocshe) in their autosound section, at least here they do. Not sure how consistently accurate it is though.......
SQLThump on 10/24/2007 16:46:02
The SPL meter will work, it will go pretty low, I used it to DB test my car a few months back, I only hit 116.8Db, considering the rig I am running, it wasn't too bad. It would give me different readings at different frequencies, and did the 116.8 at around 60hz, (I am guesing), and lost about 5 db on the lower note of the song I was playing. I could have gotten a much higher reading if I would of pushed gain and stuff higher, or went closre to thew subs. But I figured an accurate reading of what I usually listen at would be much better.
I thought of picking up one of the Schoshe meters from wallyworld, and it looked like a POS so I browsed right past it. The one Pops has is far better looking thanthat, and has a few nifty features.
Didn't think of checking Radio Shack though, I will have to take a look.
But yeah, if my crap drivers will work, I will try this out as soone as me and Pops have a coinciding day off.
SQLThump on 11/18/2007 19:04:58
Wow, major delays in the project. Spent waaaaay to much money on Halloween, and a few other recent occasions, so I will need another couple of weeks to get the spending money back up.
I do plan to test the corner frequency again, I just need to get some test tones as they all got "accidentally" deleted off of my parent's computer. DOH! Anybody got any links for some good ones? I know of one that steps down 10hz every couple of seconds, and even announces what the hz level is while it does it, but I may be hard pressed to find it again. It runs from 300hz down to 10hz.
So as long as I find the test tones I need, I will measure the corner frequency tommorrow.
On a side note, I hit a nasty pothole a month or so ago, and it hit with enough force to knock my battery hold down, the side mount terminal, and a few other things loose, along with disconneting a vital wiring clip that partially melted and caused my lights not to work. The car stalled in the middle of the road, and long story short, it sucked, but most issues were corrected the next morning when I busted out a nice once over.
But there was still an issue that was waaay out of line. My lights were flickering like mad after that on frequent, but not constant occaisons, (most of the time)to the point it seemed the car would nearly die, and triggered the ABS warning light for some odd reason, but on odd times would not have any problems at all.
Went and did another once over today, and realized what I had missed. the ground post was barely hanging on by thread. Had to unbolt a few things to tighten 'er back up, but now everything works great 100% of the time. Restored some lost faith in my car, and everything is working and running much better. Goes to show, that even with the years of working on car audio, that sometimes something so elementary can be missed, and then go on to cause a laundry list of problems until fixed. Definitely had me a rookie moment. Now I know if I have flickering problems again, to check the **** terminals.
swez on 11/18/2007 20:46:21
That's a interesting story and "who'd a thunk" a battery terminal was the culprit all along? It's an obvious point to check, but we often look for more complex issues first, chase the tail a bit and then go back to the fundamentals when all else fails huh? LOL
Swez
SQLThump on 11/19/2007 00:38:51
Yeah, it can drive a person mad when something like that happens. Dont get me started on some of my H/T lunacy that my reciever throws me................
swez on 11/19/2007 05:21:27
Hey, we all do it in one way or another. The problem often gets worse as we get more knowledge under the belt. We often tend to look for the exotic and rare or 1/10000th % rather than the simple and routine.
Why do you think most "genius" level thinkers suffer the greatest as they cogitate? They have too many levels to process the many "what if" scenarios and it drives them batty.
Swez
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