Although these things have been around for years, I have never considered using them until now.
Here's the scenario:
I plan on running two Credence eights (150 rms each) ported in .33 cf each with a f3 around 30-35hz (per say manufacturer). They will be powered by a US Acoustic 2150 @4ohm (150 rms). A perfect match? Wrong. No subsonic filter to protect the subs. Being that I play a lot of heavy bass music, I'm in fear of overexcursing at full power below f3 and causing damage.
Does anyone know if a highpass 12db octave slope @ 30hz is steep enough to work? What about the line voltage. I'm quite sure it will eat it up somewhat. My HU is only 2 volts (f & r) and the 2150 will be fed rca signal via USB 4065 preouts. That is where I start to have doubts with the FMods. It is a very simple quick fix, but "other" filters I have seen are at least 18db or higher.
Is there any other powered separate filter available without being on a processor, EQ, x-over, etc. Unless I can get my hands on a good & inexpensive used Harrison Labs EQ with a filter and no x-over, I'm not sure what to do. I've seen one on ebay that was nice but, it was a bit more complex than I'd like. Still that's the only other option I know of at this point.
Replies (27)
swez on 05/12/2005 22:13:23
The F-Mods are a pretty good fit if you are using a ported enclosure. If sealed, no need for them as the box controls F3 function of the subs. A 30 Hz SSF (HPF) will be fine with a slope of -12dB/oct.
As for low HU RCA voltage, this may become an issue later to address. As I see it, you have 2 volts HU output being split to 6 inputs. That's pretty light as each input will see ~.33 volts. If the amps are very quiet as external noise rejection goes, it may work fine.
One thing you could do, is run the sub amp using the HU rear speaker high signal outputs to the USX-2150. Then use a Hi/low adapter to convert to RCA's and feed these to the F-Mods that plug into amp inputs. That will work and set ya back about $45.00 for the whole deal. The 4 channel amp will get ~0.5 volts per channel of RCA voltage. That should be enough to drive the mid/high amp to full potential. Gain settings are the key.
The other option I have mentioned before is a Line Driver + EQ. Bahn makes a few very good ones and the Q6 will do a very nice job on adequate line out voltage to both amps and you get EQ and separate bass and full range gain controls as well. Have seen them off E-bay for ~$60.00 +S/H. If it were me, this would be the option I would shoot at.
Swez
asplundher on 05/12/2005 23:39:55
Let me clarify what I said if I confused you. There are two sets ((front and rear) of 2 volt rca's, I assume. Enough to feed the USB 4065 with no prob. The 4065 would then feed the 2150 the low pass signal. Yet, a simple SSF inline with the 2150's input wiil suffice if the FMOD's (since you say) are capable of proper slope. The 2150's fed rca voltage is what concerns me even if the slope is steep enough. What is the 4065's rca output voltage when fed a specific voltage. Then how much will the FMODS eat up?
Victor on 05/13/2005 00:30:39
Wow.. with the HU, Wiring, Preouts, Amp, F-mods, EQ, ........and all those...
All i can imagine is MULTIPLYING DISTORTION with every added electronic circuitry...
I know many of you wud argue here and all.. but The simpler an audio system the cleaner it plays.
I am more into SQ so would definitely avoid suggesting using any kind of extra circuitry unless its a die hard situation.
Also I would suggest buying the best ones made from the best selected materials. I would make it a point to see to it how much the Original signal is altered before planning on such kind of system..
Manytimes just looking for a different HU, or AMP or SUB-SETUP is far more economical, hassel free and much more better in terms of Quality.
Ofcourse the choice is to be made by you,
Victor...
swez on 05/13/2005 12:03:00
Thanks for clarifying your situation.
Most amplifiers have a 10 Kohm input impedence value. Running all 4 RCA channels to the 4065 is a sure bet. Adequate power to run that amp just fine.
The split inputs for the 2150 (sub amp) is also a 10 Kohm impedence load. There are 2 inputs here right? By my rough calcs, the 4065 will get about 2 volts max per channel. No problems here. The 2150 will get ~1.0 volts per channel. That should be adequate as well.
The F-Mod insertion losses will be less than 20%, so a 0.8 volt signal past the F-Mods should be enough to drive the 2150 to full output if the gains are set properly.
I suggest trying things as is and see what ya get. If there are noise problems or low RCA input voltages, the 2150 may need some additional help with a line driver.
NOTE: You will have to set the gains on the 4065 at ~ 2.0 volts sensitivity. The gain settings for the 2150 will need to be tweaked a tad for best performance and minimal distortion. Figure your gain range on the 2150 will need to be 0.5-1.0 volts range.
Start the 2150 at 0.5 volts input sensitivity and adjust until max clean output to subs are noted. I think you may be OK with this, if noise does not become an issue at these gain settings. (engine whine is the most logical noise issue to listem for)
Swez
asplundher on 05/13/2005 13:05:54
Victor, you lost me dude. I'm not planning to run all those accessories at once. That would be redundant. They were only options if one or the other didn't work out.
Anyway, thanks for the info on the voltage. That's just what I wanted to know.
I just found another component that just might suit my needs. A AudioControl Matrix. A multi-line driver with a SSF. I'll update you on what I decide on. I'm not to enthusiastic about the low voltage. If I have to add a line driver anyway then I might as well get everything in one package and be done with it.
If you know of any others that are similiar to the Matrix let me know. I'm still researching it to see about it's connectivity.
asplundher on 05/14/2005 07:28:33
I've checked out the Matrix and seems okay except for the price and size.
What about the PAC line drivers? They seem to be very simple but are they clean? I want to use as less space as possible and a combo of the FMOD and PAC Turbo 1 seem to be a easy and inexpensive solution.
swez on 05/14/2005 11:13:30
Got a few links to PAC products. Will check them out for you and make some suggestions.
Swez
asplundher on 05/18/2005 19:41:08
Yo swez, have you found anything else on the PAC line driver?
What about the FMOD's? The manufacturer recommends a steep order SS filter @ 35hz for full power handling. I would consider 18db or higher steep. What do you think? If that is the case, then I will have to go some other route.
swez on 05/18/2005 20:27:41
Let's review a 12dB filter characteristics:
Given:
1. Amp is full range, 100 watts at a given ohmic rating
2. We want to port the sub(s) at say 30-35 hz
3. We employ a -12dB/octave filter (SSF)
4. The filter has 40 Hz cuttoff point
What power will get to the subs at various frequencies?
40 Hz = no filtering effect to speak of
35 Hz = F3 point, -3 dB (50 watts to sub)
30 Hz = -6dB down (25 watts to sub)
25 Hz = -9dB down (12.5 watts to sub)
20 Hz = -12dB down (6.25 watts to sub)
The dB slope is actually logrithmic, not linear. The Hz. numbers used are just a rough estimates. To get a more accurate picture of how the filter will actually work, takes some advanced math or a special crossover calculator for exact frequencies ans dB down points.
An 18dB/oct slope is steeper than a 12 db version. Great for SSF's too. The main thing here, the amp often needs a phase correction circuit to bring the subs into phase alignment with mids/highs.
A 12dB filter will be almost 100% in phase as the signals pass through the coils and caps. Coils lag by 90 degrees while caps lead by 90 degrees. When using an 18db filter, the phase angle could lead or lag the mid/highs by about 90 degrees, depending on the design and internal components used. That's why a phase adjustment device is needed for 18dB filters.
Confussed? Don't feel bad... this is pretty advanced electronics theory and design info. I don't fully have a handle on it either.
Swez
asplundher on 05/20/2005 19:59:31
Well it has gone from simple to getting towards expensive but, I really want to maximize my install. I've been searching hard for a component that has it all (SSF, phase shift, and line driver). All I found after a very deep extended search was a Alto SUB16. The info looked good but, can't seem to find any dealers. I'm waiting on a response from the company on where they are sold. Yet, I fear they are going to cost a pretty penny!
Ever heard of that comapny (Alto)? Any further suggestions on that kind of combo? I can find one with some of the features but, not all. I can get a phase shift and a separate line driver/SSF but, I'm worried that it will be too much trouble (and price probably) adding two extra components just for that purpose.
swez on 05/20/2005 21:02:04
This is getting very complicated Ash. Finding a line driver with a SSF is becoming a nightmare.
I still believe the best solution for the price is a combination of LD/EQ and passive F-Mods for your SSF needs. Again, the Audiobahn AEQ6Q Equalizer/LD has all the basic and advanced features needed to power each amp mentioned.
Adding a pair of HP (SSF) F-mods to the input side of your USX-2150 should be more than adequate and no phase adjustsment tools are needed.
The F-Mods are ~$30.00 a set. Just need to know what frequency the subs are tuned for. F-Mods come stock at 30 and 40 Hz... SSF filtering slope is -12dB/oct. If using 8" subs, I would suggest the 40 Hz., version, depending on the PTF of your sub enclosure.
The Bahn unit has active EQ, 2 RCA inputs and 6 outs. Four are full range and 2 are subs. Your amps already have the required HP/LP filtering circuits on board. The nice thing about this LD/EQ, is small size, 8 volts max output and 6 outs to feed all amps adequately. It is 1/2 Din size, so in-dash mounting is possible or just tuck it away, where you can adjust things from your driver's seat. Some hard shopping to get a good price on this unit as the only challenge left.
Installing this little device is a breeze. It does need a 12 volt supply line and Rem trigger, but you can tap these from HU and fuse panel.
What say you Ash?
Swez
PS Do you have a link to the subs noted above? A spec sheet would be most helpful. What is your PTF target for them?
asplundher on 05/20/2005 22:01:18
Nightmare? I know. I apologize if I'm causing a stir, it's just that I know the potential of these subs are very good. They sound dang good sealed but, my music selection has always sounded better ported. The EBP of these also suggests that they suit that better as well, so I want them to be able to reach that full potential. Yet, I want to protect them as well. If the phase shift will not be a problem then I'll just go for a line driver/SSF. That will be the simplest and cost effective for me at this point. Poweracoustik makes one that's adjustable and I'm quite sure it's pretty inexpensive.
As for the EQ, my Pioneer 4700 HU is well suited for my tastes.
Anyway, heres the sub's link:
http://www.credencespeakers.com/Technical%20Specs.htm
Also, heres the recommended enclosure specs as well:
http://www.credencespeakers.info/pages/3/index.htm
swez on 05/20/2005 23:23:32
OK, reviewed the specs and yes, use a 40 Hz HP (SSF) on the ported version. Yes, the specs say 35 Hz and a steep rolloff curve, but can accomplish similar performance using a -12dB /oct slope, starting at 40 Hz.
I did see several PA LD's that would meet your needs too. Much cheaper than Bahn, if you don't need more EQ or desire to control Mid/highs and Subs separately from the LD. Etronics has a good selection of PA crossovers & LD's.
Good luck,
Swez
PS Yes, I did spend over an hour bending the web sites for products... but if this works well, time well spent.
asplundher on 05/22/2005 09:39:31
One problem with that idea...they don't have a 40hz FMOD. At least I haven't seen one and I have looked all over for one. Man is this getting tiresome. The Alto-Sub16 is hard to find in the states and already goes for 199 England bucks (more here) even though it might be worth it, so that's out the door as well. The only other option that I have been looking at is a Poweracoustik Bass-10 linedriver/SSF. Problem with that as well..... can't find any online dealer with one! Must be a new release or something.
I can't take it anymore! I'm gonna jump off the nearest curb and into oncoming traffic! Why do I have to be so particular when it comes to my installs?!!!!!!
swez on 05/22/2005 11:22:42
This is becoming a real maze and no cheeze to guide the mouse huh?
That Power Acoustik Bass-10 may do the job here. I ask that you contact the maker and find out what the PFM filter can do. There are no pdf's or manuals for that item listed on the site. Before you dive in and buy it, need to make sure it will do what you need. Ideally, it's a variable sweep SSF with 12-18dB/oct. (20-50 Hz SSF?) filtering characteristics.
Tech-support@poweracoustik.com
Also, it notes balanced line inputs for this device. Will it work in unbalanced input sources too? An installer/user's manual would be most helpful. Ask if they can send it to your via e-mail and we can review same, before you dive in.
Swez
PS Keep your chin up... This project is a real dilly! But if we can get the right products for you, it will be worth it.
cplkittle on 05/22/2005 23:41:55
I'm not knocking the manufacturer's recommendations, but a .33^ft box with a 30-35Hz F3? from my experience, the only way that would work is with a 10' port. Unless you are using 4" drivers. I don't have the T/S parameters for those, but I would suggest reconfiguring the box size with a program such as WINISD. or any online calculator. The F3 could somehow be 30-35, but the tuned frequency is going to be above 150Hz.
swez on 05/23/2005 09:40:58
Interesting comment there Kit.... have not looked at that aspect of the sub enclosure design to date. The ported box spec is .33 cf per sub, sealed or ported. The port recommendation is 21.25" long and 2.5" ID. To get that much porting duct work inside the box, would almost have to use a serpentine port design and use a larger internal box space as we have to add the displacement of that port as well.
Ran some calcs on this port size and in a .33 cf, 21.25" x 2.5" ID port, we get a PTF of 41.5 Hz. If you wanted to go lower than that, the port will be even longer. The displacement of the port in this application will be ~0.05 cf. So the internal box air space needs to be .33 + .05 = 0.38 cf per chamber. If the box is now made, (.33 cf/internal) ports will have to be istalled outside the box. Some creativity needed here to look innovative.
Ash, have you constructed the enclosures for these subs yet? If yes or no, what are the internal dimensions used/planned for this sub application? If you elect to go ported, we need to look at how to make a port of that dimension, fit in to or outside of the enclosure(s).
Comments?
Swez
asplundher on 05/23/2005 23:13:25
The box I have is for the sealed version. I already have planned to build a new one for the ported. The way the box will be incorporated in the hatch, external ports will be used and should pose no problems for they will still fire on the same plane as the subs.
I thought about the internal problem and decided to come up with this design. I used WINISD and after reviewing the charts I saw why Credence came up with that spec. From my experience with small subs a 2.5" port per sub is way large enough for it to perform. I trust that their specs are pretty much tested thoroughly before publishing.
Thanks for the concern though. Just finding the part and trying to stay close to the recommended specs is hard enough. I emailed Poweracoustik and have not yet heard anything from them on it. Choices are getting slim. Why they're hardly any linedriver/SSF/phase shifter's on the market is beyond me. You would think that package would be basic on most of these "bass-drivers".
swez on 05/23/2005 23:36:23
Good, nothing wrong with external ports or a combination of internal/external as well. Mostly, it the looks you'll have to map out here. The length and dia. of the ports are pretty much fixed.
Also, a 2.5" ID port for an 8" sub should be fine. Not a huge come area here, so a larger port is not needed for high air velosity concerns. (port noise)
Swez
asplundher on 05/24/2005 04:45:54
Oh by the way where can I find some "flex ports"? I've seen some in prefab enclosures in a local JL retail chain. They would be perfect for the design I have in mind.
swez on 05/24/2005 19:07:50
Got me there.... not sure where those can be had. Maybe you can search enclosure making materials at: www.partsexpress.com
One thing you might consider, PVC piping material and elbows. They come in various stock sizes, very durable, easy to cut with a hacksaw or chop saw and can find this at any good home center. They are paintable and you can use 45/90 degree elbows too. Have see a few nice customized port designs off cardomain.com, using this type of approach.
Swez
PS On the ID or the pipe or flexduct, remember the larger the ID of the tube, the longer it will have to be to reach target PTF.
asplundher on 05/29/2005 13:13:25
After checking out quite a bit of products, now I'm considering if a Concert Series Epicenter will do. It has a parametric EQ along with a variable SSF. Not sure about the rest though. The Audiocontrol website states in one part that it has no line driver, then in the manual it states that the voltage can be changed for the bass control. What is the difference? Then a "phase coupled activator technology" is stated as well. What the heck is that? I've read the online manual and no info is given on that as well. Do anyone have any experience on that particular model?
swez on 05/29/2005 17:07:03
Got a pdf link to that AC model mentioned?
I like the one feature noted on several products. The PMF (a variable Digital SSF) seems like a very helpful feature to dial in precise SSF filtering. It seems to me we looked at another brand that offered that feature as well. That feature plus a line driver would be a great tool for your present install. Adding a Parametric EQ feature would pretty much complete the Bass Engine side of the install.
Swez
asplundher on 05/29/2005 18:09:25
Here you go:
http://mobileaudiocontrol.com/product.asp?Product_Id=14165&d_Id=5249&l1=5249&l2=
swez on 05/30/2005 00:38:35
That'll work great! I really like AC products. They are bullit proof, well designed and lots of flexibility.
The Para-Bass will help you fine tune the bass nodes you need most.
The Bass Restore feature might be tricky at first as it will bring back the hidden harmonics that are often lost to the mixing process. Use that feature sparingly.
The PMF (SSF) come stock out of the box with a 33 Hz., SSF Should be fine as is. (assuming these subs can actually reproduce a 33 Hz., signal in that size enclosure) The fall back modules would be 40 or 45 Hz.
Really like the Bass output voltage control panel adjustments too. Can set the output gain structure based on amp signal input needs. Very useful feature.
In short, go with it!
Swez
asplundher on 05/30/2005 10:55:06
Ok, sounds like a winner to me too! Even though there is no phase adjustment I think it will fine. Phase is rarely used but, I wanted to make sure that bass stays up front. The 5.25" in the doors need all the help they can get.
swez on 05/30/2005 11:49:50
You do have a manual phase adjustment avilable at the sub amp outputs. You can swap wiring polarities and figure out which sounds best over all.
Manually, you get "0" or 180 degrees. The one that produces the best bass in the cabin is the one to use. The signals from subs and full range are in phase when you get a full, robust sound.
Swez
PS I hope 33 Hz., is sufficient for these subs. Since they are 8" woofers, you "may" have to use a higher SSF filter module. (40 or 45 Hz. is the fall back solution)
Once all is installed, observe the woofers closely at very low bass notes. If you see cones going wild on excursion or get cone whopping sounds, use a higher SSF filter value.
Here's the scenario:
I plan on running two Credence eights (150 rms each) ported in .33 cf each with a f3 around 30-35hz (per say manufacturer). They will be powered by a US Acoustic 2150 @4ohm (150 rms). A perfect match? Wrong. No subsonic filter to protect the subs. Being that I play a lot of heavy bass music, I'm in fear of overexcursing at full power below f3 and causing damage.
Does anyone know if a highpass 12db octave slope @ 30hz is steep enough to work? What about the line voltage. I'm quite sure it will eat it up somewhat. My HU is only 2 volts (f & r) and the 2150 will be fed rca signal via USB 4065 preouts. That is where I start to have doubts with the FMods. It is a very simple quick fix, but "other" filters I have seen are at least 18db or higher.
Is there any other powered separate filter available without being on a processor, EQ, x-over, etc. Unless I can get my hands on a good & inexpensive used Harrison Labs EQ with a filter and no x-over, I'm not sure what to do. I've seen one on ebay that was nice but, it was a bit more complex than I'd like. Still that's the only other option I know of at this point.
Replies (27)
swez on 05/12/2005 22:13:23
The F-Mods are a pretty good fit if you are using a ported enclosure. If sealed, no need for them as the box controls F3 function of the subs. A 30 Hz SSF (HPF) will be fine with a slope of -12dB/oct.
As for low HU RCA voltage, this may become an issue later to address. As I see it, you have 2 volts HU output being split to 6 inputs. That's pretty light as each input will see ~.33 volts. If the amps are very quiet as external noise rejection goes, it may work fine.
One thing you could do, is run the sub amp using the HU rear speaker high signal outputs to the USX-2150. Then use a Hi/low adapter to convert to RCA's and feed these to the F-Mods that plug into amp inputs. That will work and set ya back about $45.00 for the whole deal. The 4 channel amp will get ~0.5 volts per channel of RCA voltage. That should be enough to drive the mid/high amp to full potential. Gain settings are the key.
The other option I have mentioned before is a Line Driver + EQ. Bahn makes a few very good ones and the Q6 will do a very nice job on adequate line out voltage to both amps and you get EQ and separate bass and full range gain controls as well. Have seen them off E-bay for ~$60.00 +S/H. If it were me, this would be the option I would shoot at.
Swez
asplundher on 05/12/2005 23:39:55
Let me clarify what I said if I confused you. There are two sets ((front and rear) of 2 volt rca's, I assume. Enough to feed the USB 4065 with no prob. The 4065 would then feed the 2150 the low pass signal. Yet, a simple SSF inline with the 2150's input wiil suffice if the FMOD's (since you say) are capable of proper slope. The 2150's fed rca voltage is what concerns me even if the slope is steep enough. What is the 4065's rca output voltage when fed a specific voltage. Then how much will the FMODS eat up?
Victor on 05/13/2005 00:30:39
Wow.. with the HU, Wiring, Preouts, Amp, F-mods, EQ, ........and all those...
All i can imagine is MULTIPLYING DISTORTION with every added electronic circuitry...
I know many of you wud argue here and all.. but The simpler an audio system the cleaner it plays.
I am more into SQ so would definitely avoid suggesting using any kind of extra circuitry unless its a die hard situation.
Also I would suggest buying the best ones made from the best selected materials. I would make it a point to see to it how much the Original signal is altered before planning on such kind of system..
Manytimes just looking for a different HU, or AMP or SUB-SETUP is far more economical, hassel free and much more better in terms of Quality.
Ofcourse the choice is to be made by you,
Victor...
swez on 05/13/2005 12:03:00
Thanks for clarifying your situation.
Most amplifiers have a 10 Kohm input impedence value. Running all 4 RCA channels to the 4065 is a sure bet. Adequate power to run that amp just fine.
The split inputs for the 2150 (sub amp) is also a 10 Kohm impedence load. There are 2 inputs here right? By my rough calcs, the 4065 will get about 2 volts max per channel. No problems here. The 2150 will get ~1.0 volts per channel. That should be adequate as well.
The F-Mod insertion losses will be less than 20%, so a 0.8 volt signal past the F-Mods should be enough to drive the 2150 to full output if the gains are set properly.
I suggest trying things as is and see what ya get. If there are noise problems or low RCA input voltages, the 2150 may need some additional help with a line driver.
NOTE: You will have to set the gains on the 4065 at ~ 2.0 volts sensitivity. The gain settings for the 2150 will need to be tweaked a tad for best performance and minimal distortion. Figure your gain range on the 2150 will need to be 0.5-1.0 volts range.
Start the 2150 at 0.5 volts input sensitivity and adjust until max clean output to subs are noted. I think you may be OK with this, if noise does not become an issue at these gain settings. (engine whine is the most logical noise issue to listem for)
Swez
asplundher on 05/13/2005 13:05:54
Victor, you lost me dude. I'm not planning to run all those accessories at once. That would be redundant. They were only options if one or the other didn't work out.
Anyway, thanks for the info on the voltage. That's just what I wanted to know.
I just found another component that just might suit my needs. A AudioControl Matrix. A multi-line driver with a SSF. I'll update you on what I decide on. I'm not to enthusiastic about the low voltage. If I have to add a line driver anyway then I might as well get everything in one package and be done with it.
If you know of any others that are similiar to the Matrix let me know. I'm still researching it to see about it's connectivity.
asplundher on 05/14/2005 07:28:33
I've checked out the Matrix and seems okay except for the price and size.
What about the PAC line drivers? They seem to be very simple but are they clean? I want to use as less space as possible and a combo of the FMOD and PAC Turbo 1 seem to be a easy and inexpensive solution.
swez on 05/14/2005 11:13:30
Got a few links to PAC products. Will check them out for you and make some suggestions.
Swez
asplundher on 05/18/2005 19:41:08
Yo swez, have you found anything else on the PAC line driver?
What about the FMOD's? The manufacturer recommends a steep order SS filter @ 35hz for full power handling. I would consider 18db or higher steep. What do you think? If that is the case, then I will have to go some other route.
swez on 05/18/2005 20:27:41
Let's review a 12dB filter characteristics:
Given:
1. Amp is full range, 100 watts at a given ohmic rating
2. We want to port the sub(s) at say 30-35 hz
3. We employ a -12dB/octave filter (SSF)
4. The filter has 40 Hz cuttoff point
What power will get to the subs at various frequencies?
40 Hz = no filtering effect to speak of
35 Hz = F3 point, -3 dB (50 watts to sub)
30 Hz = -6dB down (25 watts to sub)
25 Hz = -9dB down (12.5 watts to sub)
20 Hz = -12dB down (6.25 watts to sub)
The dB slope is actually logrithmic, not linear. The Hz. numbers used are just a rough estimates. To get a more accurate picture of how the filter will actually work, takes some advanced math or a special crossover calculator for exact frequencies ans dB down points.
An 18dB/oct slope is steeper than a 12 db version. Great for SSF's too. The main thing here, the amp often needs a phase correction circuit to bring the subs into phase alignment with mids/highs.
A 12dB filter will be almost 100% in phase as the signals pass through the coils and caps. Coils lag by 90 degrees while caps lead by 90 degrees. When using an 18db filter, the phase angle could lead or lag the mid/highs by about 90 degrees, depending on the design and internal components used. That's why a phase adjustment device is needed for 18dB filters.
Confussed? Don't feel bad... this is pretty advanced electronics theory and design info. I don't fully have a handle on it either.
Swez
asplundher on 05/20/2005 19:59:31
Well it has gone from simple to getting towards expensive but, I really want to maximize my install. I've been searching hard for a component that has it all (SSF, phase shift, and line driver). All I found after a very deep extended search was a Alto SUB16. The info looked good but, can't seem to find any dealers. I'm waiting on a response from the company on where they are sold. Yet, I fear they are going to cost a pretty penny!
Ever heard of that comapny (Alto)? Any further suggestions on that kind of combo? I can find one with some of the features but, not all. I can get a phase shift and a separate line driver/SSF but, I'm worried that it will be too much trouble (and price probably) adding two extra components just for that purpose.
swez on 05/20/2005 21:02:04
This is getting very complicated Ash. Finding a line driver with a SSF is becoming a nightmare.
I still believe the best solution for the price is a combination of LD/EQ and passive F-Mods for your SSF needs. Again, the Audiobahn AEQ6Q Equalizer/LD has all the basic and advanced features needed to power each amp mentioned.
Adding a pair of HP (SSF) F-mods to the input side of your USX-2150 should be more than adequate and no phase adjustsment tools are needed.
The F-Mods are ~$30.00 a set. Just need to know what frequency the subs are tuned for. F-Mods come stock at 30 and 40 Hz... SSF filtering slope is -12dB/oct. If using 8" subs, I would suggest the 40 Hz., version, depending on the PTF of your sub enclosure.
The Bahn unit has active EQ, 2 RCA inputs and 6 outs. Four are full range and 2 are subs. Your amps already have the required HP/LP filtering circuits on board. The nice thing about this LD/EQ, is small size, 8 volts max output and 6 outs to feed all amps adequately. It is 1/2 Din size, so in-dash mounting is possible or just tuck it away, where you can adjust things from your driver's seat. Some hard shopping to get a good price on this unit as the only challenge left.
Installing this little device is a breeze. It does need a 12 volt supply line and Rem trigger, but you can tap these from HU and fuse panel.
What say you Ash?
Swez
PS Do you have a link to the subs noted above? A spec sheet would be most helpful. What is your PTF target for them?
asplundher on 05/20/2005 22:01:18
Nightmare? I know. I apologize if I'm causing a stir, it's just that I know the potential of these subs are very good. They sound dang good sealed but, my music selection has always sounded better ported. The EBP of these also suggests that they suit that better as well, so I want them to be able to reach that full potential. Yet, I want to protect them as well. If the phase shift will not be a problem then I'll just go for a line driver/SSF. That will be the simplest and cost effective for me at this point. Poweracoustik makes one that's adjustable and I'm quite sure it's pretty inexpensive.
As for the EQ, my Pioneer 4700 HU is well suited for my tastes.
Anyway, heres the sub's link:
http://www.credencespeakers.com/Technical%20Specs.htm
Also, heres the recommended enclosure specs as well:
http://www.credencespeakers.info/pages/3/index.htm
swez on 05/20/2005 23:23:32
OK, reviewed the specs and yes, use a 40 Hz HP (SSF) on the ported version. Yes, the specs say 35 Hz and a steep rolloff curve, but can accomplish similar performance using a -12dB /oct slope, starting at 40 Hz.
I did see several PA LD's that would meet your needs too. Much cheaper than Bahn, if you don't need more EQ or desire to control Mid/highs and Subs separately from the LD. Etronics has a good selection of PA crossovers & LD's.
Good luck,
Swez
PS Yes, I did spend over an hour bending the web sites for products... but if this works well, time well spent.
asplundher on 05/22/2005 09:39:31
One problem with that idea...they don't have a 40hz FMOD. At least I haven't seen one and I have looked all over for one. Man is this getting tiresome. The Alto-Sub16 is hard to find in the states and already goes for 199 England bucks (more here) even though it might be worth it, so that's out the door as well. The only other option that I have been looking at is a Poweracoustik Bass-10 linedriver/SSF. Problem with that as well..... can't find any online dealer with one! Must be a new release or something.
I can't take it anymore! I'm gonna jump off the nearest curb and into oncoming traffic! Why do I have to be so particular when it comes to my installs?!!!!!!
swez on 05/22/2005 11:22:42
This is becoming a real maze and no cheeze to guide the mouse huh?
That Power Acoustik Bass-10 may do the job here. I ask that you contact the maker and find out what the PFM filter can do. There are no pdf's or manuals for that item listed on the site. Before you dive in and buy it, need to make sure it will do what you need. Ideally, it's a variable sweep SSF with 12-18dB/oct. (20-50 Hz SSF?) filtering characteristics.
Tech-support@poweracoustik.com
Also, it notes balanced line inputs for this device. Will it work in unbalanced input sources too? An installer/user's manual would be most helpful. Ask if they can send it to your via e-mail and we can review same, before you dive in.
Swez
PS Keep your chin up... This project is a real dilly! But if we can get the right products for you, it will be worth it.
cplkittle on 05/22/2005 23:41:55
I'm not knocking the manufacturer's recommendations, but a .33^ft box with a 30-35Hz F3? from my experience, the only way that would work is with a 10' port. Unless you are using 4" drivers. I don't have the T/S parameters for those, but I would suggest reconfiguring the box size with a program such as WINISD. or any online calculator. The F3 could somehow be 30-35, but the tuned frequency is going to be above 150Hz.
swez on 05/23/2005 09:40:58
Interesting comment there Kit.... have not looked at that aspect of the sub enclosure design to date. The ported box spec is .33 cf per sub, sealed or ported. The port recommendation is 21.25" long and 2.5" ID. To get that much porting duct work inside the box, would almost have to use a serpentine port design and use a larger internal box space as we have to add the displacement of that port as well.
Ran some calcs on this port size and in a .33 cf, 21.25" x 2.5" ID port, we get a PTF of 41.5 Hz. If you wanted to go lower than that, the port will be even longer. The displacement of the port in this application will be ~0.05 cf. So the internal box air space needs to be .33 + .05 = 0.38 cf per chamber. If the box is now made, (.33 cf/internal) ports will have to be istalled outside the box. Some creativity needed here to look innovative.
Ash, have you constructed the enclosures for these subs yet? If yes or no, what are the internal dimensions used/planned for this sub application? If you elect to go ported, we need to look at how to make a port of that dimension, fit in to or outside of the enclosure(s).
Comments?
Swez
asplundher on 05/23/2005 23:13:25
The box I have is for the sealed version. I already have planned to build a new one for the ported. The way the box will be incorporated in the hatch, external ports will be used and should pose no problems for they will still fire on the same plane as the subs.
I thought about the internal problem and decided to come up with this design. I used WINISD and after reviewing the charts I saw why Credence came up with that spec. From my experience with small subs a 2.5" port per sub is way large enough for it to perform. I trust that their specs are pretty much tested thoroughly before publishing.
Thanks for the concern though. Just finding the part and trying to stay close to the recommended specs is hard enough. I emailed Poweracoustik and have not yet heard anything from them on it. Choices are getting slim. Why they're hardly any linedriver/SSF/phase shifter's on the market is beyond me. You would think that package would be basic on most of these "bass-drivers".
swez on 05/23/2005 23:36:23
Good, nothing wrong with external ports or a combination of internal/external as well. Mostly, it the looks you'll have to map out here. The length and dia. of the ports are pretty much fixed.
Also, a 2.5" ID port for an 8" sub should be fine. Not a huge come area here, so a larger port is not needed for high air velosity concerns. (port noise)
Swez
asplundher on 05/24/2005 04:45:54
Oh by the way where can I find some "flex ports"? I've seen some in prefab enclosures in a local JL retail chain. They would be perfect for the design I have in mind.
swez on 05/24/2005 19:07:50
Got me there.... not sure where those can be had. Maybe you can search enclosure making materials at: www.partsexpress.com
One thing you might consider, PVC piping material and elbows. They come in various stock sizes, very durable, easy to cut with a hacksaw or chop saw and can find this at any good home center. They are paintable and you can use 45/90 degree elbows too. Have see a few nice customized port designs off cardomain.com, using this type of approach.
Swez
PS On the ID or the pipe or flexduct, remember the larger the ID of the tube, the longer it will have to be to reach target PTF.
asplundher on 05/29/2005 13:13:25
After checking out quite a bit of products, now I'm considering if a Concert Series Epicenter will do. It has a parametric EQ along with a variable SSF. Not sure about the rest though. The Audiocontrol website states in one part that it has no line driver, then in the manual it states that the voltage can be changed for the bass control. What is the difference? Then a "phase coupled activator technology" is stated as well. What the heck is that? I've read the online manual and no info is given on that as well. Do anyone have any experience on that particular model?
swez on 05/29/2005 17:07:03
Got a pdf link to that AC model mentioned?
I like the one feature noted on several products. The PMF (a variable Digital SSF) seems like a very helpful feature to dial in precise SSF filtering. It seems to me we looked at another brand that offered that feature as well. That feature plus a line driver would be a great tool for your present install. Adding a Parametric EQ feature would pretty much complete the Bass Engine side of the install.
Swez
asplundher on 05/29/2005 18:09:25
Here you go:
http://mobileaudiocontrol.com/product.asp?Product_Id=14165&d_Id=5249&l1=5249&l2=
swez on 05/30/2005 00:38:35
That'll work great! I really like AC products. They are bullit proof, well designed and lots of flexibility.
The Para-Bass will help you fine tune the bass nodes you need most.
The Bass Restore feature might be tricky at first as it will bring back the hidden harmonics that are often lost to the mixing process. Use that feature sparingly.
The PMF (SSF) come stock out of the box with a 33 Hz., SSF Should be fine as is. (assuming these subs can actually reproduce a 33 Hz., signal in that size enclosure) The fall back modules would be 40 or 45 Hz.
Really like the Bass output voltage control panel adjustments too. Can set the output gain structure based on amp signal input needs. Very useful feature.
In short, go with it!
Swez
asplundher on 05/30/2005 10:55:06
Ok, sounds like a winner to me too! Even though there is no phase adjustment I think it will fine. Phase is rarely used but, I wanted to make sure that bass stays up front. The 5.25" in the doors need all the help they can get.
swez on 05/30/2005 11:49:50
You do have a manual phase adjustment avilable at the sub amp outputs. You can swap wiring polarities and figure out which sounds best over all.
Manually, you get "0" or 180 degrees. The one that produces the best bass in the cabin is the one to use. The signals from subs and full range are in phase when you get a full, robust sound.
Swez
PS I hope 33 Hz., is sufficient for these subs. Since they are 8" woofers, you "may" have to use a higher SSF filter module. (40 or 45 Hz. is the fall back solution)
Once all is installed, observe the woofers closely at very low bass notes. If you see cones going wild on excursion or get cone whopping sounds, use a higher SSF filter value.
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