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Discussion Starter · #1 ·
given that aperiodic is free-air with two rooms, does anybody here have any setups in that you use a membrane to control the woofers with maybe some kind of eq/control box to flatten out the resonant freq within the woofer/s. thank angelo.
 

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I have heard of it being done in car audio but never in home audio. It sure would be a hoot to play around with though. They sell the kits for car audio I wonder how hard it would be to tweak for home use.

Matt
 

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Elite Shackster
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OK, so basically they are covering the driver with some sort of Membrane, separate to the baffle the driver is held in?

If so, I can see how it may be advantageous in a car, but not sure why anyone would desire this in a home, especially in an IB application.
 

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Discussion Starter · #6 ·
well, in a car, the membrane's give the woofer the perfect size box regardless of freq., so it has a real flat output which richard clark and david navone of autosound 2000 tweaked with a eq box of sorts depending on the woofer's q . back in the day of early car audio, the speakerworks buick grand national took the scene by storm. not too much later richard clark (audio engineer) bought it and reworked it to a mind blowing system. way ahead it's time as it took some pro stuff, car stuff, and his own hand built devices to make it the ultimate car audio system. i have never heard a car that could equal it. 2-15" woofers, 2 -12" midbass's and two hand built waveguide horns. 6 drivers, time aligned and eq'd to perfection. home setups had a hard time doing what this car was doing with imaging. anyway, the membrane just gives the woofer the extra control that flattens out the responce and not making the woofer depend on the spider for it's sole complience. the only true requirement in car was 100% front to back isolation. i would think that this would be easy in a attic to main listening room.
 

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The whole point of an IB is that you use large drivers and multiples of them. This is so the system can move masses of air with very little movement. It gives lots of low distortion bass at spls above what we would normally need. The multi driver array gives high system power handling, which again in turn leads to under worked amps giving out very clean output.

An IB is designed to work in an infinite baffle system, so adding a membrane to one side of the driver would destroy its performance. I would liken that kind of setup more akin to a high powered sealed sub. In a car, such a subwoofer would be amazingly good, where cabin gain negates the need for ported systems. The improved group delay of sealed subs helps lead to an accuracy of sounds, and the sealed cab improves impulse response. I suspect this is the idea with the membrane. Of course, you would need driver specifically tailored for that kind of application, which I can see working in a car very well, but not in a home or dedicated HT. A true IB, as far as I can get my head into this, would be far superior, not least in terms of sheer output.
 

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Your are correct Moonfly in terms of sheer output the multiple drivers of an IB setup would be better.
The benefit to the aperiodic is sound quality as is the impedance curve of the woofer is virtually flat and the q is tuned perfect. From what I have heard the sound is very similar to a well tuned TL. It is the only box I have never tried and I would love to do so.

I remember reading about that Buick back in the day but did not realize they used pro audio time alignment gear. That is just way to cool. :T
That car had to sound amazing.

Matt
 

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Elite Shackster
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Ib's also have a very high sound quality (derived from a system working very relaxed), and have a designed Q, unless it is significantly altered by using a 'cabinet' that is to small or non IB specific drivers, but then its no longer a true IB.
 

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Ib's also have a very high sound quality (derived from a system working very relaxed), and have a designed Q, unless it is significantly altered by using a 'cabinet' that is to small or non IB specific drivers, but then its no longer a true IB.
The big selling point for me with the IB vs. the aperiodic is the efficiency. My understanding is that when you use the mat you use loose efficiency.

I have not tried the mat but would love to.

Here is a link to a kit.
https://www.madisound.com/store/product_info.php?products_id=1323

Dynaudio has a speaker using the tech http://www.dynaudio.com/eng/archive/lines/contour/contour1.php
 

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Its starting to make sense now. These would work with sealed boxes, but not IB's, as IB's essentially operate in free air anyway. I would think though, that for these to work best, they would have to ideally be tailored for your specific build. Also, sealed subs are the smallest of all home based subwoofer designs, which probably makes size much less of an issue. Also, fromthe reading I'm doing, a larger sealed box is likely more efficient than a smaller aperiodic box of equal Q.

System Q is not hard to alter in the home, but in a vehicle where cabin gain is much higher then your likely always fighting a high system Q. This is likely why a lot of car audio applications use automotive IB drivers. The one place I could see these working well in the home perhaps, is with in wall subwoofers.
 

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Ya, that is basically what i understand aperiodic setups to be.

I wonder if you could build a well designed one with an LLT to bring down the size of the enclosure. mmmmmmmm

Matt
 

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The words 'trial and error' spring to mind. Its not beyond or means with tools like REW, but it would sure test the patience of my other half.
 
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