How hard is Fernandes setup?
01-07-2004, 02:33 PM
#1
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Join Date: Jan 2003
Posts: 1,571
How hard is Fernandes setup?
How hard would it to build a setup like his in my 4th gen? Here is his.. click link
01-07-2004, 08:01 PM
#3
Why don't you ask him?
Tony is very clean and detailed with his work and I think he probably spent a lot of time and effort getting everything just right. He helped me out with a lot of my questions on my install. I would anticipate several hours worth of sealing off the trunk, along with the same for the enclosure. I would think for one person this is a pretty full weekend job, but like I said, you should ask Tony.
BTW, that looks sweet, Tony...
Tony is very clean and detailed with his work and I think he probably spent a lot of time and effort getting everything just right. He helped me out with a lot of my questions on my install. I would anticipate several hours worth of sealing off the trunk, along with the same for the enclosure. I would think for one person this is a pretty full weekend job, but like I said, you should ask Tony.
BTW, that looks sweet, Tony...
01-08-2004, 12:06 PM
#4
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Join Date: Aug 2002
Posts: 719
Aperiodic Membrane or Variovent is nothing new. The idea is actually some 50 years old. It is acually a method of using restrictive vent to dampen the resonant frequency of an enclosure. It is like using a really good stuffing material. It allows you to use an enclosure that is smaller than would be allowed using traditional methods. It will not give you any SPL gain.
Was the trunk isolation necessary to trap out of phase bass response due to the leaky vents?
Was the trunk isolation necessary to trap out of phase bass response due to the leaky vents?
01-12-2004, 04:43 AM
#5
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Join Date: Oct 2001
Posts: 1,771
Originally Posted by Maxima Dan
Aperiodic Membrane or Variovent is nothing new. The idea is actually some 50 years old. It is acually a method of using restrictive vent to dampen the resonant frequency of an enclosure. It is like using a really good stuffing material. It allows you to use an enclosure that is smaller than would be allowed using traditional methods. It will not give you any SPL gain.
Was the trunk isolation necessary to trap out of phase bass response due to the leaky vents?
Was the trunk isolation necessary to trap out of phase bass response due to the leaky vents?
Actually, an AP box will significantly reduce SPL output versus a traditional box. However, I noticed that having the subs mounted directly behind the seats helped make up for this disparity versus the box-in-the-trunk method.
Tony
01-12-2004, 04:45 AM
#6
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Join Date: Oct 2001
Posts: 1,771
Originally Posted by 94M@X
Dont know, but he did a great job, very clean install. I am inspired!!
Everyone stay tuned. I'm feeling inspired this week on my days off to get my Dynaudios off my garage shelf and into the front doors. 8" mid-woofers in the doors and 3-inch midranges and tweets in kick panels.
Tony
01-12-2004, 04:50 AM
#7
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Join Date: Oct 2001
Posts: 1,771
Originally Posted by Red92MaxSE
Why don't you ask him?
Tony is very clean and detailed with his work and I think he probably spent a lot of time and effort getting everything just right. He helped me out with a lot of my questions on my install. I would anticipate several hours worth of sealing off the trunk, along with the same for the enclosure. I would think for one person this is a pretty full weekend job, but like I said, you should ask Tony.
BTW, that looks sweet, Tony...
Tony is very clean and detailed with his work and I think he probably spent a lot of time and effort getting everything just right. He helped me out with a lot of my questions on my install. I would anticipate several hours worth of sealing off the trunk, along with the same for the enclosure. I would think for one person this is a pretty full weekend job, but like I said, you should ask Tony.
BTW, that looks sweet, Tony...
Thank you very much!!
Yes...I am EXTREMELY detailed oriented. If you ask my friends they'll tell you I'm TOO detail oriented.
I am a firm believer that a system with mediocre equipment and an excellent install will sound better than one with audiophile-quality equipment and a poorly designed or just plain bad install. I'm striving to have both.
BTW...any time Redmax!!
Tony
01-12-2004, 05:04 AM
#8
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Join Date: Oct 2001
Posts: 1,771
Originally Posted by sk24iam
How hard would it to build a setup like his in my 4th gen? Here is his.. click link
I guess to answer your question I would need to know how patient you are. The AP box was extremely time consuming and I did TONS of research before I even started. Even the physical aspect was harder than I imagined. I lost count of how many times I had to crawl into my trunk and lay on my back with my legs curled up with all my tools scattered around me. I even burnt the crap out of my hands and arms on the heat gun because I kept forgetting to keep away from it!! It was pretty exhausting...but worth it.
Some good sources of information are www.termpro.com and www.carsound.com. The search features work great and the senior members really know their stuff.
If you need any help just ask. I'm no expert but I've learned a few things over the years.
Tony
01-12-2004, 10:35 AM
#9
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Join Date: Aug 2002
Posts: 719
Originally Posted by Tony Fernandes
Yes. Trunk isolation is an absolute necessity to prevent cancellation. Possibly the most important aspect of the install.
Actually, an AP box will significantly reduce SPL output versus a traditional box. However, I noticed that having the subs mounted directly behind the seats helped make up for this disparity versus the box-in-the-trunk method.
Tony
Actually, an AP box will significantly reduce SPL output versus a traditional box. However, I noticed that having the subs mounted directly behind the seats helped make up for this disparity versus the box-in-the-trunk method.
Tony
01-12-2004, 05:12 PM
#10
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Join Date: Oct 2001
Posts: 1,771
Originally Posted by Maxima Dan
Looks really good. How much less internal volume were you able to use and is there any concern about overpowering the vent and blowing out the fill? Just curious, I might consider something similar for my next setup if possible.
Tony
01-14-2004, 11:51 PM
#11
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Posts: n/a
Below is the short version of AP enclosure design. Northcreek Music owner, George Short III did either his masteres or Doctoral thesis on the AP. I couln't find the link on the site, but it is there someplace. I had to cut and paste from my file.
http://www.northcreekmusic.com
North Creek Music's new MAPD driver loading
MAPD = Multichamber Aperiodic Progressive Damping
Abstract: A new driver loading technique in which a driver is loaded by a first small chamber that is aperiodically coupled into a second, larger chamber, is described. The loading technique has the advantages of both simple Acoustic Suspension loading and the Aperiodically Damped loading techniques, without the disadvantage of either. Optimum driver parameters and cabinet volumes are described.
by George E. Short III, President, North Creek Music Systems, March 11, 2001
MAPD loading is an acoustic loading technique I have been thinking about and occasionally working on for over a decade, and have finally succeeding in optimizing in both the North D28 tweeter and North Creek Music Vision Revelator Signature loudspeaker. The new North 19W-6542-S-06 woofer was also designed specifically to take advantage of this technique.
Acoustic Suspension loading, developed by AR (Acoustic Research) in the early 1950's, is a simple sealed box loading in which the box volume is less than or equal to one-third of the driver's suspension equivalent volume, Vas.
Vab = Vas/3
The benefit of Acoustic Suspension loading is that the air "spring" trapped inside the acoustic suspension cabinet is much stronger than the driver suspension "spring" (i.e. the spider and surround). The air "spring" is extremely linear, far more linear than even the best driver suspension "spring". What this means to the driver is that even at very high output levels, the cone motion is very well controlled simply because the air "spring" forces the driver to behave. A side benefit of Acoustic Suspension loading is that at very low frequencies the maximum driver excursion is reduced compared to the same driver in either free air or vented box loading. Also, the high pass roll off is second order below system resonance.
The disadvantages of Acoustic Suspension loading are that it forces the system Qtc to be at least twice the driver Qts, and it forces the system resonance frequency Fc to be at least twice the driver resonance frequency, Fs.
Qtc/Qts = Fc/Fs = 2
While Qtc going up is not necessarily a bad thing, with Qtc between 0.7 and 1.0 generally sounding quite good, a Qtc above 1.1 will ring slightly and tend to very slightly favor the resonance frequency. Although never as overbearing as the "one note bass" found in badly tuned vented systems and most bandpass subwoofers, a Qtc above 1.1 will still tend to lend its "character" to any program the system is trying to reproduce.
Aperiodic Damping of Acoustic Suspension systems with Qtc of above 1.1 is a cure for both the ringing and the "character", as Aperiodic Damping eliminates the ringing and adjusts the effective Q of the system. As the flow resistance of the Aperiodic Damping device can be adjusted, a preferred loading can usually be found rather quickly. What the preferred loading actually turns out to be is purely subjective.
The disadvantages of Aperiodic Damping of Acoustic Suspension designs are 1) that the system high pass roll off becomes third order below system resonance, and 2) the maximum driver excursion is controlled only by the driver suspension, and is actually equal to or greater than the driver excursion of a vented box system, and much greater than the original Acoustic Suspension system from which the Aperiodically Damped system was created.
MAPD (Multichamber Aperiodic Progressive Damping) loading is an extension of the Aperiodically Damped Acoustic Suspension loading, in which the Acoustic Suspension system is loaded into a second, much larger chamber via an aperiodic vent. This loading technique retains or created the following advantages: 1) the driver suspension is still dominated by the linear air "spring" of the first acoustic suspension enclosure; 2) the system high pass roll off remains second order below resonance; 3) the low frequency driver excursion is reduced compared to the vented or standard Aperiodic loading, although still higher than the simple Acoustic Suspension loading; 4) the system's effective Qtc can be "fine tuned" by fine adjustments to the aperiodic vent between the first and second chambers; 5) the MAPD system has superior impulse response compared to an Acoustic Suspension system with Qtc above 1.1. The disadvantage is that the required cabinet volume is several times that required by a simple Acoustic Suspension system.
One could argue that for most drivers, one could achieve superior impulse response by simply using the larger cabinet to begin with. As this results in a lower Qtc and also a lower system resonance frequency. While this is true and the loading technique for drivers with a Qts below 0.55, the larger cabinet does not yield the superior suspension performance of the linear air spring of the small, Acoustic Suspension enclosure.
So what kind of driver is a perfect candidate for MAPD loading? It is an interesting question because the technique was first optimized during the development of the North D28 tweeter rear chamber loading, not with a woofer at all! But, the best driver for MAPD loading is a woofer with a Qtc of about 0.60, and preferably with a small Vas.
The design example is the Scan Speak 15S-8530K-01, which North Creek has tested over the last two years and averaged the following Theile-Small numbers:
Fs = 44 Hz
Qts = 0.610
Qes = 0.65
Qms = 9.8
Vas = 12.50 liters
Here the loading we use is that featured in the new North Creek Vision Revelator Signature loudspeaker, which is an MTM. The box volumes per woofer is 4.17 liters for the first enclosure, 12.5 liters for the second, yielding an overall net volume of 33.3 liters for the pair. The aperiodic damping for the woofers is provided by a single Scan Speak Scan-Vent adjoining the first, 8.34 liter section to the second, 25 liter section. The volume of the second enclosure is exactly equal to the drivers' equivalent suspension volume, Vas, to provide symmetry around the small Acoustic Suspension enclosure.
Vab1 = Vas/3
Vab2 = Vas
Whether other volume ratios offers advantages is yet to be determined, but selecting this volume ratio greatly simplifies the mathematical model, which usually directly translates to better results in the real world.
The systems overall characteristics are: the Acoustic Suspension loading of the first chamber raises the system Qtc to 1.22. Acoustic damping (stuffing) in the first volume drops the Qmc from 19.6 to about 12.0, so the effective Qtc is actually closer to 1.21. Aperiodically coupling into the second chamber drops the Qm much lower, to about 5.0 (hence the term "Progressive Damping"), and also lowers the system resonance frequency slightly. Overall, the system performs as one with an effective Qtc just under 1.0, and is -3dB at 68 Hz. For a resonance frequency in the 80 Hz range, this is rich, robust, and detailed yet satisfying tuning.
For a loudspeaker using 5" woofers to cleanly reproduce mid-bass at respectable volumes, suspension linearity of even a Scan Speak driver is insufficient. MAPD loading provides the optimum environment for this driver.
A Caveat for Technical Information on this Subject:
Invariably when we release a publication of this nature, we receive a very large number of requests for more detailed technical information, copies of the derivation and measurements, and occasionally requests for a more detailed explanation. So I have to say at the beginning that North Creek Music does not have the facilities or the personnel to provide more in-depth technical support on this subject other than this brief report and the cabinet drawings for the North Creek Vision Signature loudspeaker. The best free advise I can give on MAPD is this: with a driver with a Qts of 0.6 or above, this is the best way I have found to tune its low end, and with generally spectacular results. Try it!
http://www.northcreekmusic.com
North Creek Music's new MAPD driver loading
MAPD = Multichamber Aperiodic Progressive Damping
Abstract: A new driver loading technique in which a driver is loaded by a first small chamber that is aperiodically coupled into a second, larger chamber, is described. The loading technique has the advantages of both simple Acoustic Suspension loading and the Aperiodically Damped loading techniques, without the disadvantage of either. Optimum driver parameters and cabinet volumes are described.
by George E. Short III, President, North Creek Music Systems, March 11, 2001
MAPD loading is an acoustic loading technique I have been thinking about and occasionally working on for over a decade, and have finally succeeding in optimizing in both the North D28 tweeter and North Creek Music Vision Revelator Signature loudspeaker. The new North 19W-6542-S-06 woofer was also designed specifically to take advantage of this technique.
Acoustic Suspension loading, developed by AR (Acoustic Research) in the early 1950's, is a simple sealed box loading in which the box volume is less than or equal to one-third of the driver's suspension equivalent volume, Vas.
Vab = Vas/3
The benefit of Acoustic Suspension loading is that the air "spring" trapped inside the acoustic suspension cabinet is much stronger than the driver suspension "spring" (i.e. the spider and surround). The air "spring" is extremely linear, far more linear than even the best driver suspension "spring". What this means to the driver is that even at very high output levels, the cone motion is very well controlled simply because the air "spring" forces the driver to behave. A side benefit of Acoustic Suspension loading is that at very low frequencies the maximum driver excursion is reduced compared to the same driver in either free air or vented box loading. Also, the high pass roll off is second order below system resonance.
The disadvantages of Acoustic Suspension loading are that it forces the system Qtc to be at least twice the driver Qts, and it forces the system resonance frequency Fc to be at least twice the driver resonance frequency, Fs.
Qtc/Qts = Fc/Fs = 2
While Qtc going up is not necessarily a bad thing, with Qtc between 0.7 and 1.0 generally sounding quite good, a Qtc above 1.1 will ring slightly and tend to very slightly favor the resonance frequency. Although never as overbearing as the "one note bass" found in badly tuned vented systems and most bandpass subwoofers, a Qtc above 1.1 will still tend to lend its "character" to any program the system is trying to reproduce.
Aperiodic Damping of Acoustic Suspension systems with Qtc of above 1.1 is a cure for both the ringing and the "character", as Aperiodic Damping eliminates the ringing and adjusts the effective Q of the system. As the flow resistance of the Aperiodic Damping device can be adjusted, a preferred loading can usually be found rather quickly. What the preferred loading actually turns out to be is purely subjective.
The disadvantages of Aperiodic Damping of Acoustic Suspension designs are 1) that the system high pass roll off becomes third order below system resonance, and 2) the maximum driver excursion is controlled only by the driver suspension, and is actually equal to or greater than the driver excursion of a vented box system, and much greater than the original Acoustic Suspension system from which the Aperiodically Damped system was created.
MAPD (Multichamber Aperiodic Progressive Damping) loading is an extension of the Aperiodically Damped Acoustic Suspension loading, in which the Acoustic Suspension system is loaded into a second, much larger chamber via an aperiodic vent. This loading technique retains or created the following advantages: 1) the driver suspension is still dominated by the linear air "spring" of the first acoustic suspension enclosure; 2) the system high pass roll off remains second order below resonance; 3) the low frequency driver excursion is reduced compared to the vented or standard Aperiodic loading, although still higher than the simple Acoustic Suspension loading; 4) the system's effective Qtc can be "fine tuned" by fine adjustments to the aperiodic vent between the first and second chambers; 5) the MAPD system has superior impulse response compared to an Acoustic Suspension system with Qtc above 1.1. The disadvantage is that the required cabinet volume is several times that required by a simple Acoustic Suspension system.
One could argue that for most drivers, one could achieve superior impulse response by simply using the larger cabinet to begin with. As this results in a lower Qtc and also a lower system resonance frequency. While this is true and the loading technique for drivers with a Qts below 0.55, the larger cabinet does not yield the superior suspension performance of the linear air spring of the small, Acoustic Suspension enclosure.
So what kind of driver is a perfect candidate for MAPD loading? It is an interesting question because the technique was first optimized during the development of the North D28 tweeter rear chamber loading, not with a woofer at all! But, the best driver for MAPD loading is a woofer with a Qtc of about 0.60, and preferably with a small Vas.
The design example is the Scan Speak 15S-8530K-01, which North Creek has tested over the last two years and averaged the following Theile-Small numbers:
Fs = 44 Hz
Qts = 0.610
Qes = 0.65
Qms = 9.8
Vas = 12.50 liters
Here the loading we use is that featured in the new North Creek Vision Revelator Signature loudspeaker, which is an MTM. The box volumes per woofer is 4.17 liters for the first enclosure, 12.5 liters for the second, yielding an overall net volume of 33.3 liters for the pair. The aperiodic damping for the woofers is provided by a single Scan Speak Scan-Vent adjoining the first, 8.34 liter section to the second, 25 liter section. The volume of the second enclosure is exactly equal to the drivers' equivalent suspension volume, Vas, to provide symmetry around the small Acoustic Suspension enclosure.
Vab1 = Vas/3
Vab2 = Vas
Whether other volume ratios offers advantages is yet to be determined, but selecting this volume ratio greatly simplifies the mathematical model, which usually directly translates to better results in the real world.
The systems overall characteristics are: the Acoustic Suspension loading of the first chamber raises the system Qtc to 1.22. Acoustic damping (stuffing) in the first volume drops the Qmc from 19.6 to about 12.0, so the effective Qtc is actually closer to 1.21. Aperiodically coupling into the second chamber drops the Qm much lower, to about 5.0 (hence the term "Progressive Damping"), and also lowers the system resonance frequency slightly. Overall, the system performs as one with an effective Qtc just under 1.0, and is -3dB at 68 Hz. For a resonance frequency in the 80 Hz range, this is rich, robust, and detailed yet satisfying tuning.
For a loudspeaker using 5" woofers to cleanly reproduce mid-bass at respectable volumes, suspension linearity of even a Scan Speak driver is insufficient. MAPD loading provides the optimum environment for this driver.
A Caveat for Technical Information on this Subject:
Invariably when we release a publication of this nature, we receive a very large number of requests for more detailed technical information, copies of the derivation and measurements, and occasionally requests for a more detailed explanation. So I have to say at the beginning that North Creek Music does not have the facilities or the personnel to provide more in-depth technical support on this subject other than this brief report and the cabinet drawings for the North Creek Vision Signature loudspeaker. The best free advise I can give on MAPD is this: with a driver with a Qts of 0.6 or above, this is the best way I have found to tune its low end, and with generally spectacular results. Try it!
01-15-2004, 12:04 AM
#12
Guest
Posts: n/a
Sorry, I should have included this as well, from RIchard Clark and David Navone's tech briefs:
http://www.autosound2000.com/detail....ODUCT_ID=A2596
And this, from elitecaraudio.com:
http://elitecaraudio.com/article.php?sid=18
The only large speaker company that I have spoken with, or with speaker design engineers, that seems to have good concrete knowledge of AP systems is JBL. I don't know that there is any company that spends more on R & D than JBL.
If you have any questions after reading these sources, just ask. Sounds like tony has great first hand knowledge. I've read just about everything that has been published with the words "aperiodic membrane" or synonyms of the same.
http://www.autosound2000.com/detail....ODUCT_ID=A2596
And this, from elitecaraudio.com:
http://elitecaraudio.com/article.php?sid=18
The only large speaker company that I have spoken with, or with speaker design engineers, that seems to have good concrete knowledge of AP systems is JBL. I don't know that there is any company that spends more on R & D than JBL.
If you have any questions after reading these sources, just ask. Sounds like tony has great first hand knowledge. I've read just about everything that has been published with the words "aperiodic membrane" or synonyms of the same.
01-15-2004, 03:12 AM
#13
Senior Member
Join Date: Oct 2001
Posts: 1,771
Originally Posted by jmax
Sorry, I should have included this as well, from RIchard Clark and David Navone's tech briefs:
http://www.autosound2000.com/detail....ODUCT_ID=A2596
And this, from elitecaraudio.com:
http://elitecaraudio.com/article.php?sid=18
The only large speaker company that I have spoken with, or with speaker design engineers, that seems to have good concrete knowledge of AP systems is JBL. I don't know that there is any company that spends more on R & D than JBL.
If you have any questions after reading these sources, just ask. Sounds like tony has great first hand knowledge. I've read just about everything that has been published with the words "aperiodic membrane" or synonyms of the same.
http://www.autosound2000.com/detail....ODUCT_ID=A2596
And this, from elitecaraudio.com:
http://elitecaraudio.com/article.php?sid=18
The only large speaker company that I have spoken with, or with speaker design engineers, that seems to have good concrete knowledge of AP systems is JBL. I don't know that there is any company that spends more on R & D than JBL.
If you have any questions after reading these sources, just ask. Sounds like tony has great first hand knowledge. I've read just about everything that has been published with the words "aperiodic membrane" or synonyms of the same.
Tony
01-15-2004, 09:08 AM
#14
Guest
Posts: n/a
That's a nice little write-up. Too bad they don't have links to the how and why of AP enclosures. I think the first time I read about AP set-ups was when I read David Weems Great Sound Stereo Speaker Manual, in 1990. He gives info about the Dynaudio / Scan-Speak variovent. Either that book or farther back in time when RC was still raved about in every car audio mag with his AP set-up using JBL pro drivers in the Grand National. Pretty much everything to do with AP car subs comes from RC introduceing them to the auto sound competition scene. He has a lot of good info about them in the Autosound 2000 Tech Briefs. His current stance is that woofer desgn has changed enough that the best overall enclosures are sealed boxes. This likely has to do with the fact that an AP tuned properly isn't very lively for the majority of music currently on the market. Probaly 99.9% of the population prefer a bit of a bump in the 40-60 Hz range. And the fact that we have been listening to distortion for so long that 99.9% believe it belongs in the music. We actually miss it when it is gone.
01-15-2004, 09:48 AM
#15
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Join Date: Aug 2002
Posts: 719
That was an interesting read, thanks Jmax. It is definately an interesting idea. But when you consider that Soundstream's minnimum recomended enclosure volume for that sub is .5ft^3, how many people will really go through the effort to save around .15ft^3 or so. I could see using this technique back when drivers needed more space, but today it is pretty easy to find a driver to run in a really tight space and still have a relatively small Qtc.
Now something interesting might be to fing a driver with a really large Vas and try a true MAPD setup. But the volume of the second chamber will vary depending on what's being carried in the trunk.
Now something interesting might be to fing a driver with a really large Vas and try a true MAPD setup. But the volume of the second chamber will vary depending on what's being carried in the trunk.
01-15-2004, 01:08 PM
#16
Guest
Posts: n/a
Originally Posted by Maxima Dan
Now something interesting might be to fing a driver with a really large Vas and try a true MAPD setup. But the volume of the second chamber will vary depending on what's being carried in the trunk.
01-15-2004, 03:29 PM
#17
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Join Date: Oct 2001
Posts: 1,771
Originally Posted by jmax
Unless for example you significantly vent the trunk to the outside useing additional resistive membranes. It just might not be legal to have the vehicle vented in that manner for some types of SQ and SPL competitions. This free-air type of set up has been disqualifiying in some cases because it allows the sub much greater efficiency. Essentially the car becomes the sealed enclosure playing in the outdoors.
Tony
01-15-2004, 03:34 PM
#18
Senior Member
Join Date: Oct 2001
Posts: 1,771
Originally Posted by Maxima Dan
That was an interesting read, thanks Jmax. It is definately an interesting idea. But when you consider that Soundstream's minnimum recomended enclosure volume for that sub is .5ft^3, how many people will really go through the effort to save around .15ft^3 or so. I could see using this technique back when drivers needed more space, but today it is pretty easy to find a driver to run in a really tight space and still have a relatively small Qtc.
Tony
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