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Hey Kiki
Posted: Sun Mar 20, 2005 7:30 pm
by ridr4lif
What exactly is an "aperiodic" enclosure or whatever it is called? Do you know of any links that explain it or can you explain?
TEDD
Posted: Sun Mar 20, 2005 7:32 pm
by Justin from Detroit1
Private Messages
Posted: Sun Mar 20, 2005 7:33 pm
by ridr4lif
I was going to PM him but maybe other people dont kno what that enclosure is either. Just thought it could benefit everybody but myself.
TEDD
Posted: Sun Mar 20, 2005 8:46 pm
by nist7
What I found on the SoundDomain Forum
An aperiodic enclosure is a version of a infinite baffle (free-air) subwoofer setup. The subwoofer is in a small box, usually just big enough to fit around the sub. One side of the box has a special membrane that allows the woofer to force air through it and into the area behind the box. The membrane is usually made from fiberglass insulation. The amount of fiberglass used determines how the aperiodic enclosure is tuned.
Designs from Autosound 2000 had the membrane infront of the woofer, attached like a grill. There were no box on the backside of the woofer.
This is how the aperiodic enclosure works. When the sub plays low frequencies that makes the woofer cone move alot, the air from the back of the sub is easily forced through the membrane. The resulting deep sound is just like an infinte baffle setup. When the woofer is playing higher frequencies, the membrane does not let the air move through. The result is like having the sub in a very small box. (Good for higher bass frequencies.) The density of the membrane dictates how much air passes, therefore producing bass from "loose" to "tight".
Aperiodics lets the user have a very small sub enclosure. It is also somewhat easier to tune. All you have to do is experiment with the density of the membrane to get the sound you desire.
There are downsides. First you must be able to keep the sound from the front and back of the woofer seperate. Basically, you must have a trunk. There have been aperiodics built in trucks and hatchbacks, but the woofer's back sound wave is usually sent outside. Second, they are less efficient than other designs. You get less bass for the same power.
I would suggest you have alot of experience with sealed and infinite baffle sub systems before you try an infinite baffle design.
Chuck Music
IASCA Pro 301-600
Posted: Sun Mar 20, 2005 8:55 pm
by Jonathan
The tutorial on Elite Car Audio is very good. Aperiodic really gives the effect of a larger sealed box more so than a small one. What you are doing is tuning the membrane's density to mechanically dampen the resonant frequency of the driver, which in turn flattens the impedance curve.
http://www.elitecaraudio.com/article.php?sid=18
Posted: Sun Mar 20, 2005 9:16 pm
by ridr4lif
Wow...just checked out that article. Seems kinda confusing. I dont think i will ever be constructing one of those anytime soon.
Taken from
http://www.elitecaraudio.com
[HTML]In kicks, hatchbacks, vans, and SUVs, the membrane must fire OUT of the car (Yes, that’s right, outside the car!). [/HTML]
How would this be done? It almost sounds like you need to cut a hole in the vehicle?
TEDD
Posted: Mon Mar 21, 2005 8:37 am
by nist7
Seems like it, or I guess cutting a hole in the window.
In any event, AP enclosures seems to be suited for cars with limited amount of space to work with, So in SUVs and Vans you might as well go for a true sealed box.
Posted: Mon Mar 21, 2005 8:42 am
by ridr4lif
Yea...i probably wouldnt go for an a-periodic enclosure...i just want to learn as much as i can about diff enclosure types and such. After i built my ported box i dont think im ever gonna build anything else...
TEDD
Posted: Mon Mar 21, 2005 10:18 am
by GlassWolf
an AP box works in any vehicle with a sealed, separated air space for the enclosure, like a sedan. hatchbacks and SUVs need to have the enclosure vented to outside air to work properly.
An AP enclosure gives the response of a sealed enclosure but without the boominess associated with sealed boxes. the AP box offers tighter control of the driver with suppressed 2nd and 3rd order harmonics. It's an ideal SQ enclosure, but not great for SPL since it's -3dB down from sealed due to the membrane.
more on AP enclosures:
http://www.elitecaraudio.com/article.php?sid=18
http://www.maximacar.com/aperiodic.htm
Posted: Mon Mar 21, 2005 10:29 am
by ridr4lif
hatchbacks and SUVs need to have the enclosure vented to outside air to work properly
How would one go about doing this though? I am just curioius.
TEDD