okay fellas well i finaly blew my two audiobahn 12 (aw121t) last night i let all of the smoke out of the wires and no matter how hard i tried i couldent get the smoke back in so im looking for a new set up i liked that kenwood amp(KAC-9152D) this may be a keeper i found them for about 150 on ebay so now i need some subs im looking at around a 150 budjet on these also so subs and amp $300 what do you all sudjest thanks a lot
Replies (29)
swez on 09/7/2006 16:12:45
That Kenwood amp is a strong player. The Bahn subs.... not up to par as you now know. Just make sure your amp is getting all the power it needs to remain clean and strong for the next sub pair to buy.
Am sure a few guys will chime in on sub choices and so will I. However, right now, I have to break off. Will come back to this later and see what others have mentioned.
FYI: You may need to look at some serious SPL Comp subs. These ain't cheap either. One brand that does come to mind that is more budget level, but strong might be Power Acoustik's Fubar or MoFo's. These are built pretty well, but not up to the standards we find in JL W7's, Kicker W7 and Orion H2's.
Swez
Ash on 09/7/2006 18:43:05
Swez is right. That amp puts out some serious power and will require some just as serious subs. Subs that may be out of the $150 range for the pair.
One thing that must be touched on is what type of enclosure and sound do you prefer? PA's competition subs mostly require ported and are not recommended for sealed. Are you still going to stay with the same box you have now or build another to suit the new drivers (best option)?
Finding close to a 900 rms watts pair of 12"s may give a limited choice when 2 ohms is the limit. Dual 2 ohm coils or single 4's will have to be used. For example:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-185
This is the sub that I am currently using. Two of these will easily handle that amp with plenty of output. Works great in about 1.1- 1.4 cft sealed each. Ported will take about 2.25 each but will tune very low. Specs and warranty are excellent, as well as many rave reviews by many users. Price is not bad either. These subs are actually made by Eminence as well as Adire's version.
raulbustos on 09/7/2006 23:45:25
well ive mostly used sealed boxes before but im open to a ported box as well
raulbustos on 09/8/2006 18:50:23
hey one thing that im not sure of is that this amp states that the power is
1,800 Watts max power
500 Watts x 1 (4 ohms) RMS
900 Watts x 1 (2 ohms) RMS
900 Watts x 1 (1 ohms) RMS
so what is the difference between a 1 or 2 ohm load to this amp
and if this is true i could run either dvc or svc subs that are 4 ohms rite it wouldent make a difference either set up would net 900 rms
raulbustos on 09/8/2006 18:52:14
one other question how long should a sub last ? what determins how long one would last
Ash on 09/8/2006 18:56:41
Didn't know that about that amp (1 ohm stable). Even so, there is no advantage to it since no extra power is available. It does make it usable on different subs but at the same time it might only make it work harder and possibly shorten it's life. You would be better off running 2 ohms since you'll get the same output with more stability.
swez on 09/8/2006 19:51:01
Agree w/ Ash too. There are amps out there that can run well at 1 ohm or less loads. However, they are big current hogs and best designed for SPL Comps, not daily drivers.
Subs are like any mechanical device... if they are used in with mfg's design parameters, they last a long time. (I've never fried a sub) However, the DJ's who abused the gear we installed, have indeed done so and paid a pretty penny for the repairs and service calls.
Most subs fail/die due to misuse or abuse. This is usually in the form of too much power/heat, (fried voice coils) mechanical failures, (over-excursion) due to incorrect enclosure design or in rare cases, poor manufacturing practices.
If you want a nice pair of SQL subs for this amp, consider the Alpine SWR 1222D's. These are 2+2 DVC's, can handle a solid 500 watts RMS per sub and are very reliable. I have seen then on the net for about $120.00/ea. (+ S/H)
Here are specs:
http://www.sonicelectronix.com/viewitem.php?id=4243
Yes, a little shopping can get the price down a bit more. Just make sure the enclosure used, is close to the specs noted on that page.
Swez
Ash on 09/8/2006 21:42:30
Agreed! Any sub can last a long time if you know it's limitations and don't exceed it.
A common misconception is that a particular sub will have the same power handling when put into larger enclosures. Only a few manufacturers make that claim. For most subs, the larger the box, the lower the power handling. It is not uncommon to halve the rating when maximizing low end output. This is often the cause (other than distortion) that leads to subwoofer failure for people tend to think that they can still apply the maximum rated rms.
One thing I have always wished the manufacturers would do is give the power rating for the recommended enclosures. In sealed, normally, maximum power handling occurs @ Qtc of 1.1, which is rarely used. Most recommendations are around Qtc .707. Are they giving the rating of that? Very few like Adire do.
Using larger vented alignments are somewhat similar, but can have some protection through use of a subsonic filter.
swez on 09/8/2006 22:00:05
Well played ol Man... subs take less power in larger Qtc enclosures. For most car audio applications, A Qtc of .85 is a good blend of power handling and low bass performance. The lower the Qtc, (0.7 or lower) the sub will reach X-max with less power and can self destruct at rated power.
Also, those Dayton subs mentioned earlier, are a good option too. These are dual 8+8 DVC's and your net ohmic load in full parallel is a solid 2 ohms. (a very good match for that amp) They can handle 600 watts RMS/sub, have good efficiency and can be used in sealed, ported or BP applications with very good results.
These are made by Eminence for PE's Dayton line. Eminence is probably one of the largest speaker makers in the USA. They make HT, Car Audio and Pro Line subs for very reasonalble prices. I would not turn up my nose at these Dayton's either. Besides, if you have questions or need technical inputs on a given application, PE does a great job of supporting their customers. (I buy things from PE when needed and find them an excellent supplier in all ways)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-185
This sub may not be as flashy as some brands. However, they put their money into the guts, where performance really counts!
Swez
Ash on 09/9/2006 00:48:09
I hope we're not causing confusion, but as you see, there can be quite a bit involved in choosing the right driver. However, if you know what you're dealing with ahead, then your choices will become clearer.
There are quite a bit of subs that would be adequate for that amp. What you will need to do to narrow it down is figure out exactly how do you want it to sound, how much "real estate" do you want to designate, and how much do actually want to spend on a good pair (total).
Then once you've figured out what set you want to go with, shop around for the best deal (with warranty). I suggest warranty because this will be a somewhat steep investment.
Victor on 09/9/2006 03:18:47
To understand this """ Qtc """ if its confusing you... you may wanna go through this once..
http://www.members.shaw.ca/LoudSpeakerBuilder.ca/thiele-small.html
Victor...
swez on 09/9/2006 09:10:18
Nice link Vic!
Only one problem... there are probably 3-4 guys on this board that will understand it well enough to benefit. LOL
Well written, somewhat easy to understand for those who have a background in speaker design and electronic filters, ect., but well over the heads of most readers here.
Care to summerize the highlights and make an FAQ/DIY article from this info in your own words and understanding of same?
Swez
raulbustos on 09/10/2006 23:31:16
okay well if i remember rite my curent box is a sealed box with 1.7 cf per chamber now this is the largest box i could use if posible i would like to use this box again since i worked verry hard on this box and i think it came out verry nice .but its not set in stone also this kenwood amp looks to be a good deal however once again not set in stone. now i like the kenwood amp and the alpine type R subs but with the best price i could find is 419 for both now i think this is a verry good option but wel see if i could find a good set up for about 300 that would be nice but if i fell that there isnt enough quality there well then its not worth it then so if you all have some other recomended products id like to know
raulbustos on 09/10/2006 23:44:22
and i read that link but like swez expected its a litle technical for me
swez on 09/11/2006 06:14:51
A box with 1.7 ft^3 per chamber is VERY large for most Car 12's. This means either modifying the box or looking for subs that can mate to that box, take the power mentioned and still sound good in that size box and keep the price down to a range that you can afford. This is a very tall order Raul.
A sub that comes to mind & loves a big box and can handle the power, would be something like Kicker's L5 or L7 series. They are not cheap, not very efficient, but love a large box. This option is well out of budget for a pair of them and that Kenwood amp.
Now, you can use the same box for other less expensive subs, but you'll have to load the box with something to bring the interior airspace down to about 1.0 - 1.25 ft^3 per chamber. That usually means adding boards (2x4's) inside the box, to fill up each chamber. This is also adding some weight and doing some internal mods to bring each chamber into optimal range for the next set of subs used.
Are you willing to do this step if needed? It will allow this box to be used again, but this time, you'll have more luck with the subs of choice as they will be in a more suitable enclosure. (Sure beats tossing this box and starting over)
Comments?
Swez
raulbustos on 09/11/2006 10:14:30
well if needed i mite consider puting in some 2x4s in my box but if i was to go with some thing that needs a smaller box i think i would just rather build a new box although i would hate to just toss this box the idea of a much heavier box breaks my back since i had a very hard time moving my box as it is i mean i could aslways sell this box but well see also another ideah would the alpine type R s work good in this box?
cybersailor420 on 09/11/2006 22:23:26
I just wanted to say to Victor, I just finished reading everything on that website you posted... That is an awesome website! I understood most of that stuff already, but it definitely clarified the few gaps I had here and there. I looked at one of his DIY kits, and really like his design and innovation. Great descriptions of everything too.
-Ian-
swez on 09/11/2006 22:34:39
If you went ported with this box, yes the Alpine type R's will work.
» sealed box volume: 0.57-1.00 cu. ft.
» ported box volume: 0.75-1.70 cu. ft.
Just remember if you go ported, you'll need an Infrasonic/Subsonic filter, tuned below PTF. (Port Tuning Freq)
NOTE: " Recommended Vented Box Volume: The vented box sizes recommended by Alpine range from 0.75 cu/ft to 2.0 cu/ft. Within this range, the ideal size recommended by Alpine is 1.7 cu/ft, so this is the enclosure recommended by Crutchfield. A slot port with the following dimensions should be used with the 1.7 cu/ft enclosure: W=12", H=1.25", L=21". If you cannot use a slot port in your enclosure, you will need a port tube with the following dimensions: Diameter=3", L=9.9"."
Alpine suggests a 1.7 ft^3 enclosure and vent dimensions of:
Slot Length: 12.0"
Slot Width" 1.25"
Port length: 21.0"
Port volume displacement: 0.305 ft^3
Net internal volume: 1.3 ft^3 (Vb inc. port and sub displacements)
PTF/Fo: 36.0 Hz.
F3: 32 Hz. is -3dB down point
Actually, by just pure luck the box you have now, will indeed accomdate a pair of Type R's. It may be a tad heavier due to port materials and this sub is pretty hefty too. The mounting depth is almost 8.0" too.
I'd say you're on the right track with ported Alpine R's.
What say you... Lucky or what?
Swez
raulbustos on 09/18/2006 14:01:09
okay um just to make sure i cant remeber how to get the volume of a box so make sure for me please my outside dementions was 14x15.5x36 HxDxW i put a partition in the middle of the box and i used 3/4 mdf board also looking at this the slot port wouldent work because it need to be 21 inches long rite ?
raulbustos on 09/18/2006 14:22:19
and what do you all think about the SWS-1242D subs?i found these for about 160 a pair this would fill the budget but i would need an other box but the type r look nice i like them but im going to have to wait on those they are out of my budget for now but on the plus side i allready have the perfect box for them when i can get them but these subs wouldent hold up to that kenwood amp rite so if these are some good subs i need to find an amp for them also around 150 would be good
swez on 09/18/2006 15:55:46
If your sub box is 3/4" MDF, the internal air space is 3.5 ft^3, minus the center board, (~0.1 ft^3) = 3.4 ft^3. Or, 1.7 ft^3/chamber (without subs).
If you used slotted ports, they will look like an "L" type arrangement, using the divider as part of the each chambers. The slots are 2.5" wide, and 12.5" tall and 21" long per chamber.
To get the required length for this port, we use a board that runs parallel to the divider and would be 12.5" Hx 11.5" L x 0.75" T . Then add a 2nd board 12.5" H x 8.75 L x 0.75" T to form the "L" port.
NOTE: We need to keep the port width 2.5" wide that the rear of the "L" as well. A diagram would make this much easier to understand. If you need one, shoot me your e-mail in a ClubMail message and I'll see what I can do for you. You'll need a Power Point reader for this as I do all my diagrams and sketches in .ppt format.
As for cheaper subs (Alpine SWS) and a new amp... you can use the SWS subs and your present amp. The box is OK and fits ported parameters range for SWS 12's. The SWS-1222D are the subs to use here. You'll get a net 2 ohms and if you use the amp gain to dial down the power to ~600 Wrms, these subs will be fine.
Got all that?
swez
Victor on 09/18/2006 16:02:52
i wud not do that... instead buy 2 SWS 1242 D , the 4 ohm version and wire them for a total of 4 ohm load.. this kenwood amp will give a healthy 500wrms @ 4ohms.. which would be enuf for these subs in a ported box...
comments....??
THINK
swez on 09/20/2006 14:08:12
That works too... 2 good subs, a solid amp and you won't get blinded by the "choma-affect" Bahn seems to be so fond of doing.
Also, this amp in this wiring configuration, will not draw as much current at 500 Wrms as it will at 900 Wrms. More vehicle friendly too.
Good call Victor,
swez
raulbustos on 09/21/2006 10:26:09
hey guys quick question i was looking at the stats on htis kenwood amp and i noticed that it has two 30 amp fuses now 60 x14.4=864 but this amp claims to push 900 is this amp a litlle over rated? if so what do you think is the actual power of this unit
swez on 09/21/2006 12:47:16
It would seem that Kenwood is taking full advantage of the new 14.4 volt CEA Compliant rating system. Even if the numbers are a bit low, the price this amp sells for, makes it a good bargain.
Besides, one cannot detect a -2 dB drop in output when we are talking 130dB plus SPL. Yes, a meter and scope will show it. But the ears will not pick up that minimal deviation.
In short, if this amp delivers a solid 225 +Wrms/sub, (dual subs) or 1 strong 2 ohm sub, it's still a good value VS a big name amp that costs double of this amp.
Using high efficiency subs, (90dB + SPL @ 1w1m) and a well designed ported box, will give solid bass with this amp.
swez
PS This amp is more likely to deliver about 700 Wrms @ 2 ohms and close to 400 Wrms @ 4 ohm loads. Considering the price, it's still a good value, even if the specs are a bit over-rated. (This seems obvious) Comparing this to a Kicker, HiFonics, Alpine, JL or MTX amp of similar power ratings, the difference in price is not a bad value.
If you want to know the actual power this amp can deliver, an AC voltmeter will help a lot. Your target voltages are as followed:
4 ohms: 500 Wrms nets about 44.7 volts
2 ohms: 700 Wrms nets about 37.4 volts
If these values are what you get, (or pretty darn close +/- 10%) this amp is a very good value.
raulbustos on 09/21/2006 15:05:33
okay now this is some thing i have allways wondered how to check how much power an amp is actually puting out now you say you can use a voltmeter could you give me some details as how to do this thank you
swez on 09/22/2006 08:33:58
This site link will explain the details for amp power testing:
http://www.bcae1.com/measpwr.htm
It recommends an O-Scope to measure wave form integrity and peak to peak voltage too. The author also recommends using purely resistive dummy loads as the resistance does not change with frequency as we note in speakers as loads.
However, we can get "in the ballbark" RMS values by measuring AC voltage off the speakers that are connected to the amp too. Just note the voltage values tend to change based on frequency fed to the speakers. This is due to the impedence (Z) values of speakers as they change resistive values, as frequency changes. (See the chart at the bottom of the linked page)
Hope that helps,
swez
raulbustos on 09/23/2006 19:04:53
okay that helped a bit but i have a coulpe questions what would be considered " A regulated D.C. power supply" and whats the "oscilloscope" and third of all he writes that you need "A set of high power resistors" what exactly are these and where could i get some i would like to get a setup where i could check amps as i tend to have quiet a few pass through
swez on 09/24/2006 11:34:06
A regulated power supply allows one to manually adjust voltage output to an amp very accurately. (Ie: 12.5, 13.8, 14.4 volts) It also has to have adequate current to meet the amps' needs. These can be pretty expensive, once we go above 40A's.
Yes, you can use a car battery with a charger connected to it too. It's not as precise as a regulated power supply, but it will work.
An "O-Scope" is a very expensive piece of test gear. Some have Channel A & Channel B inputs and can display input wave forms on one channel, amp output moitoring on the other channel. Nice if you have access to one, but they are not cheap either. However, these are very good at showing even minimal clipping of amp distortions at the outputs of any amplifer. Here's a link to see what an O-scop looks like and how it is used:
http://www.bcae1.com/audoutex.htm
Also, there is a sub link in that page that shows a Sencor SC3100 scope. This is a dual channel model and 1 CRT screen. One can toggle back and forth between channels A & B to view amp input/output waveforms.
http://www.bcae1.com/oscope.htm
Note the clean sinusoidal wave shape shown on the scope? That's what we look for in low distortion amp outputs. In the next link, we see a very detailed setup using an O-scope that monitors HU and EQ/Signal processor outputs. If you go down the page a bit, see what a clipped signal looks like? We want to avoid this problem as it is very hard on mids and tweets. (Heat building failures)
Robust subs can manage a fair amount of clipping w/o damage. However, excessive amp clipping can fry a strong woofer too.
Load resistors: Ohmite Manufacturing makes most of them. They come in various resistance, wattage and power handling levels. Here's a link to what is offered by Ohmite:
http://www.ohmite.com/cgi-bin/products.cgi
Depending on the power level of the amp you are working with, you will probably need a bank of them to get the proper load value and current carry ability.
Swez
Replies (29)
swez on 09/7/2006 16:12:45
That Kenwood amp is a strong player. The Bahn subs.... not up to par as you now know. Just make sure your amp is getting all the power it needs to remain clean and strong for the next sub pair to buy.
Am sure a few guys will chime in on sub choices and so will I. However, right now, I have to break off. Will come back to this later and see what others have mentioned.
FYI: You may need to look at some serious SPL Comp subs. These ain't cheap either. One brand that does come to mind that is more budget level, but strong might be Power Acoustik's Fubar or MoFo's. These are built pretty well, but not up to the standards we find in JL W7's, Kicker W7 and Orion H2's.
Swez
Ash on 09/7/2006 18:43:05
Swez is right. That amp puts out some serious power and will require some just as serious subs. Subs that may be out of the $150 range for the pair.
One thing that must be touched on is what type of enclosure and sound do you prefer? PA's competition subs mostly require ported and are not recommended for sealed. Are you still going to stay with the same box you have now or build another to suit the new drivers (best option)?
Finding close to a 900 rms watts pair of 12"s may give a limited choice when 2 ohms is the limit. Dual 2 ohm coils or single 4's will have to be used. For example:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-185
This is the sub that I am currently using. Two of these will easily handle that amp with plenty of output. Works great in about 1.1- 1.4 cft sealed each. Ported will take about 2.25 each but will tune very low. Specs and warranty are excellent, as well as many rave reviews by many users. Price is not bad either. These subs are actually made by Eminence as well as Adire's version.
raulbustos on 09/7/2006 23:45:25
well ive mostly used sealed boxes before but im open to a ported box as well
raulbustos on 09/8/2006 18:50:23
hey one thing that im not sure of is that this amp states that the power is
1,800 Watts max power
500 Watts x 1 (4 ohms) RMS
900 Watts x 1 (2 ohms) RMS
900 Watts x 1 (1 ohms) RMS
so what is the difference between a 1 or 2 ohm load to this amp
and if this is true i could run either dvc or svc subs that are 4 ohms rite it wouldent make a difference either set up would net 900 rms
raulbustos on 09/8/2006 18:52:14
one other question how long should a sub last ? what determins how long one would last
Ash on 09/8/2006 18:56:41
Didn't know that about that amp (1 ohm stable). Even so, there is no advantage to it since no extra power is available. It does make it usable on different subs but at the same time it might only make it work harder and possibly shorten it's life. You would be better off running 2 ohms since you'll get the same output with more stability.
swez on 09/8/2006 19:51:01
Agree w/ Ash too. There are amps out there that can run well at 1 ohm or less loads. However, they are big current hogs and best designed for SPL Comps, not daily drivers.
Subs are like any mechanical device... if they are used in with mfg's design parameters, they last a long time. (I've never fried a sub) However, the DJ's who abused the gear we installed, have indeed done so and paid a pretty penny for the repairs and service calls.
Most subs fail/die due to misuse or abuse. This is usually in the form of too much power/heat, (fried voice coils) mechanical failures, (over-excursion) due to incorrect enclosure design or in rare cases, poor manufacturing practices.
If you want a nice pair of SQL subs for this amp, consider the Alpine SWR 1222D's. These are 2+2 DVC's, can handle a solid 500 watts RMS per sub and are very reliable. I have seen then on the net for about $120.00/ea. (+ S/H)
Here are specs:
http://www.sonicelectronix.com/viewitem.php?id=4243
Yes, a little shopping can get the price down a bit more. Just make sure the enclosure used, is close to the specs noted on that page.
Swez
Ash on 09/8/2006 21:42:30
Agreed! Any sub can last a long time if you know it's limitations and don't exceed it.
A common misconception is that a particular sub will have the same power handling when put into larger enclosures. Only a few manufacturers make that claim. For most subs, the larger the box, the lower the power handling. It is not uncommon to halve the rating when maximizing low end output. This is often the cause (other than distortion) that leads to subwoofer failure for people tend to think that they can still apply the maximum rated rms.
One thing I have always wished the manufacturers would do is give the power rating for the recommended enclosures. In sealed, normally, maximum power handling occurs @ Qtc of 1.1, which is rarely used. Most recommendations are around Qtc .707. Are they giving the rating of that? Very few like Adire do.
Using larger vented alignments are somewhat similar, but can have some protection through use of a subsonic filter.
swez on 09/8/2006 22:00:05
Well played ol Man... subs take less power in larger Qtc enclosures. For most car audio applications, A Qtc of .85 is a good blend of power handling and low bass performance. The lower the Qtc, (0.7 or lower) the sub will reach X-max with less power and can self destruct at rated power.
Also, those Dayton subs mentioned earlier, are a good option too. These are dual 8+8 DVC's and your net ohmic load in full parallel is a solid 2 ohms. (a very good match for that amp) They can handle 600 watts RMS/sub, have good efficiency and can be used in sealed, ported or BP applications with very good results.
These are made by Eminence for PE's Dayton line. Eminence is probably one of the largest speaker makers in the USA. They make HT, Car Audio and Pro Line subs for very reasonalble prices. I would not turn up my nose at these Dayton's either. Besides, if you have questions or need technical inputs on a given application, PE does a great job of supporting their customers. (I buy things from PE when needed and find them an excellent supplier in all ways)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-185
This sub may not be as flashy as some brands. However, they put their money into the guts, where performance really counts!
Swez
Ash on 09/9/2006 00:48:09
I hope we're not causing confusion, but as you see, there can be quite a bit involved in choosing the right driver. However, if you know what you're dealing with ahead, then your choices will become clearer.
There are quite a bit of subs that would be adequate for that amp. What you will need to do to narrow it down is figure out exactly how do you want it to sound, how much "real estate" do you want to designate, and how much do actually want to spend on a good pair (total).
Then once you've figured out what set you want to go with, shop around for the best deal (with warranty). I suggest warranty because this will be a somewhat steep investment.
Victor on 09/9/2006 03:18:47
To understand this """ Qtc """ if its confusing you... you may wanna go through this once..
http://www.members.shaw.ca/LoudSpeakerBuilder.ca/thiele-small.html
Victor...
swez on 09/9/2006 09:10:18
Nice link Vic!
Only one problem... there are probably 3-4 guys on this board that will understand it well enough to benefit. LOL
Well written, somewhat easy to understand for those who have a background in speaker design and electronic filters, ect., but well over the heads of most readers here.
Care to summerize the highlights and make an FAQ/DIY article from this info in your own words and understanding of same?
Swez
raulbustos on 09/10/2006 23:31:16
okay well if i remember rite my curent box is a sealed box with 1.7 cf per chamber now this is the largest box i could use if posible i would like to use this box again since i worked verry hard on this box and i think it came out verry nice .but its not set in stone also this kenwood amp looks to be a good deal however once again not set in stone. now i like the kenwood amp and the alpine type R subs but with the best price i could find is 419 for both now i think this is a verry good option but wel see if i could find a good set up for about 300 that would be nice but if i fell that there isnt enough quality there well then its not worth it then so if you all have some other recomended products id like to know
raulbustos on 09/10/2006 23:44:22
and i read that link but like swez expected its a litle technical for me
swez on 09/11/2006 06:14:51
A box with 1.7 ft^3 per chamber is VERY large for most Car 12's. This means either modifying the box or looking for subs that can mate to that box, take the power mentioned and still sound good in that size box and keep the price down to a range that you can afford. This is a very tall order Raul.
A sub that comes to mind & loves a big box and can handle the power, would be something like Kicker's L5 or L7 series. They are not cheap, not very efficient, but love a large box. This option is well out of budget for a pair of them and that Kenwood amp.
Now, you can use the same box for other less expensive subs, but you'll have to load the box with something to bring the interior airspace down to about 1.0 - 1.25 ft^3 per chamber. That usually means adding boards (2x4's) inside the box, to fill up each chamber. This is also adding some weight and doing some internal mods to bring each chamber into optimal range for the next set of subs used.
Are you willing to do this step if needed? It will allow this box to be used again, but this time, you'll have more luck with the subs of choice as they will be in a more suitable enclosure. (Sure beats tossing this box and starting over)
Comments?
Swez
raulbustos on 09/11/2006 10:14:30
well if needed i mite consider puting in some 2x4s in my box but if i was to go with some thing that needs a smaller box i think i would just rather build a new box although i would hate to just toss this box the idea of a much heavier box breaks my back since i had a very hard time moving my box as it is i mean i could aslways sell this box but well see also another ideah would the alpine type R s work good in this box?
cybersailor420 on 09/11/2006 22:23:26
I just wanted to say to Victor, I just finished reading everything on that website you posted... That is an awesome website! I understood most of that stuff already, but it definitely clarified the few gaps I had here and there. I looked at one of his DIY kits, and really like his design and innovation. Great descriptions of everything too.
-Ian-
swez on 09/11/2006 22:34:39
If you went ported with this box, yes the Alpine type R's will work.
» sealed box volume: 0.57-1.00 cu. ft.
» ported box volume: 0.75-1.70 cu. ft.
Just remember if you go ported, you'll need an Infrasonic/Subsonic filter, tuned below PTF. (Port Tuning Freq)
NOTE: " Recommended Vented Box Volume: The vented box sizes recommended by Alpine range from 0.75 cu/ft to 2.0 cu/ft. Within this range, the ideal size recommended by Alpine is 1.7 cu/ft, so this is the enclosure recommended by Crutchfield. A slot port with the following dimensions should be used with the 1.7 cu/ft enclosure: W=12", H=1.25", L=21". If you cannot use a slot port in your enclosure, you will need a port tube with the following dimensions: Diameter=3", L=9.9"."
Alpine suggests a 1.7 ft^3 enclosure and vent dimensions of:
Slot Length: 12.0"
Slot Width" 1.25"
Port length: 21.0"
Port volume displacement: 0.305 ft^3
Net internal volume: 1.3 ft^3 (Vb inc. port and sub displacements)
PTF/Fo: 36.0 Hz.
F3: 32 Hz. is -3dB down point
Actually, by just pure luck the box you have now, will indeed accomdate a pair of Type R's. It may be a tad heavier due to port materials and this sub is pretty hefty too. The mounting depth is almost 8.0" too.
I'd say you're on the right track with ported Alpine R's.
What say you... Lucky or what?
Swez
raulbustos on 09/18/2006 14:01:09
okay um just to make sure i cant remeber how to get the volume of a box so make sure for me please my outside dementions was 14x15.5x36 HxDxW i put a partition in the middle of the box and i used 3/4 mdf board also looking at this the slot port wouldent work because it need to be 21 inches long rite ?
raulbustos on 09/18/2006 14:22:19
and what do you all think about the SWS-1242D subs?i found these for about 160 a pair this would fill the budget but i would need an other box but the type r look nice i like them but im going to have to wait on those they are out of my budget for now but on the plus side i allready have the perfect box for them when i can get them but these subs wouldent hold up to that kenwood amp rite so if these are some good subs i need to find an amp for them also around 150 would be good
swez on 09/18/2006 15:55:46
If your sub box is 3/4" MDF, the internal air space is 3.5 ft^3, minus the center board, (~0.1 ft^3) = 3.4 ft^3. Or, 1.7 ft^3/chamber (without subs).
If you used slotted ports, they will look like an "L" type arrangement, using the divider as part of the each chambers. The slots are 2.5" wide, and 12.5" tall and 21" long per chamber.
To get the required length for this port, we use a board that runs parallel to the divider and would be 12.5" Hx 11.5" L x 0.75" T . Then add a 2nd board 12.5" H x 8.75 L x 0.75" T to form the "L" port.
NOTE: We need to keep the port width 2.5" wide that the rear of the "L" as well. A diagram would make this much easier to understand. If you need one, shoot me your e-mail in a ClubMail message and I'll see what I can do for you. You'll need a Power Point reader for this as I do all my diagrams and sketches in .ppt format.
As for cheaper subs (Alpine SWS) and a new amp... you can use the SWS subs and your present amp. The box is OK and fits ported parameters range for SWS 12's. The SWS-1222D are the subs to use here. You'll get a net 2 ohms and if you use the amp gain to dial down the power to ~600 Wrms, these subs will be fine.
Got all that?
swez
Victor on 09/18/2006 16:02:52
i wud not do that... instead buy 2 SWS 1242 D , the 4 ohm version and wire them for a total of 4 ohm load.. this kenwood amp will give a healthy 500wrms @ 4ohms.. which would be enuf for these subs in a ported box...
comments....??
THINK
swez on 09/20/2006 14:08:12
That works too... 2 good subs, a solid amp and you won't get blinded by the "choma-affect" Bahn seems to be so fond of doing.
Also, this amp in this wiring configuration, will not draw as much current at 500 Wrms as it will at 900 Wrms. More vehicle friendly too.
Good call Victor,
swez
raulbustos on 09/21/2006 10:26:09
hey guys quick question i was looking at the stats on htis kenwood amp and i noticed that it has two 30 amp fuses now 60 x14.4=864 but this amp claims to push 900 is this amp a litlle over rated? if so what do you think is the actual power of this unit
swez on 09/21/2006 12:47:16
It would seem that Kenwood is taking full advantage of the new 14.4 volt CEA Compliant rating system. Even if the numbers are a bit low, the price this amp sells for, makes it a good bargain.
Besides, one cannot detect a -2 dB drop in output when we are talking 130dB plus SPL. Yes, a meter and scope will show it. But the ears will not pick up that minimal deviation.
In short, if this amp delivers a solid 225 +Wrms/sub, (dual subs) or 1 strong 2 ohm sub, it's still a good value VS a big name amp that costs double of this amp.
Using high efficiency subs, (90dB + SPL @ 1w1m) and a well designed ported box, will give solid bass with this amp.
swez
PS This amp is more likely to deliver about 700 Wrms @ 2 ohms and close to 400 Wrms @ 4 ohm loads. Considering the price, it's still a good value, even if the specs are a bit over-rated. (This seems obvious) Comparing this to a Kicker, HiFonics, Alpine, JL or MTX amp of similar power ratings, the difference in price is not a bad value.
If you want to know the actual power this amp can deliver, an AC voltmeter will help a lot. Your target voltages are as followed:
4 ohms: 500 Wrms nets about 44.7 volts
2 ohms: 700 Wrms nets about 37.4 volts
If these values are what you get, (or pretty darn close +/- 10%) this amp is a very good value.
raulbustos on 09/21/2006 15:05:33
okay now this is some thing i have allways wondered how to check how much power an amp is actually puting out now you say you can use a voltmeter could you give me some details as how to do this thank you
swez on 09/22/2006 08:33:58
This site link will explain the details for amp power testing:
http://www.bcae1.com/measpwr.htm
It recommends an O-Scope to measure wave form integrity and peak to peak voltage too. The author also recommends using purely resistive dummy loads as the resistance does not change with frequency as we note in speakers as loads.
However, we can get "in the ballbark" RMS values by measuring AC voltage off the speakers that are connected to the amp too. Just note the voltage values tend to change based on frequency fed to the speakers. This is due to the impedence (Z) values of speakers as they change resistive values, as frequency changes. (See the chart at the bottom of the linked page)
Hope that helps,
swez
raulbustos on 09/23/2006 19:04:53
okay that helped a bit but i have a coulpe questions what would be considered " A regulated D.C. power supply" and whats the "oscilloscope" and third of all he writes that you need "A set of high power resistors" what exactly are these and where could i get some i would like to get a setup where i could check amps as i tend to have quiet a few pass through
swez on 09/24/2006 11:34:06
A regulated power supply allows one to manually adjust voltage output to an amp very accurately. (Ie: 12.5, 13.8, 14.4 volts) It also has to have adequate current to meet the amps' needs. These can be pretty expensive, once we go above 40A's.
Yes, you can use a car battery with a charger connected to it too. It's not as precise as a regulated power supply, but it will work.
An "O-Scope" is a very expensive piece of test gear. Some have Channel A & Channel B inputs and can display input wave forms on one channel, amp output moitoring on the other channel. Nice if you have access to one, but they are not cheap either. However, these are very good at showing even minimal clipping of amp distortions at the outputs of any amplifer. Here's a link to see what an O-scop looks like and how it is used:
http://www.bcae1.com/audoutex.htm
Also, there is a sub link in that page that shows a Sencor SC3100 scope. This is a dual channel model and 1 CRT screen. One can toggle back and forth between channels A & B to view amp input/output waveforms.
http://www.bcae1.com/oscope.htm
Note the clean sinusoidal wave shape shown on the scope? That's what we look for in low distortion amp outputs. In the next link, we see a very detailed setup using an O-scope that monitors HU and EQ/Signal processor outputs. If you go down the page a bit, see what a clipped signal looks like? We want to avoid this problem as it is very hard on mids and tweets. (Heat building failures)
Robust subs can manage a fair amount of clipping w/o damage. However, excessive amp clipping can fry a strong woofer too.
Load resistors: Ohmite Manufacturing makes most of them. They come in various resistance, wattage and power handling levels. Here's a link to what is offered by Ohmite:
http://www.ohmite.com/cgi-bin/products.cgi
Depending on the power level of the amp you are working with, you will probably need a bank of them to get the proper load value and current carry ability.
Swez
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