ap enclosure

[jmrunz 10+ year member]

hi, my first time here, i have been on other forums before. my question is is there anybody that can give me some insight to ap enclosures. i have a real small car and have 2 12" subs that take up the entire trunk space. i know alot about ap's but not everything. send some help please.

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[GemaRastem 10+ year member]

http://www.elitecaraudio.com/article.php?sid=18

 

[jmrunz 10+ year member]

thanks for the link. i have already read that one and it gave me my first thoughts on the enclosure. but i still have other questions that that article did not cover

james

 

[jmrunz 10+ year member]

your profile says you have 2 15" in ap. how did you design your box and how did you build it. i have my ideas but would like more. also what and how much did you use for your membrane. and the final and most important question is how does it sound. how does it compair with a ported or sealed box. what is the bottom end like and how is the sq.

james

 

[phaze23lbc 10+ year member]

I got this info from: http://www.usdaudio.com/products/ap.php

An AP subwoofer system is one which employs 2 enclosure volumes coupled with a purely resistive element, the AP Mat. When such a system is properly designed, it is possible to control the woofer cone movement by the energy transfer though the precision acoustic resistance of the AP Mat. The completed system will be considered A-periodic, or over-damped with a Q well below 0.7 Qts. In contrast, most car audio systems are grossly under damped, with Q's greater than 0.8 and higher. These high-Q systems have poor transient response, nasty peaks in their frequency response and high rates of roll-off. The result of controlling cone motion with a resistive AP Mat is a very low system Qt. A-periodic systems feature excellent transient and phase response, smooth frequency response and extended very-low frequency reproduction with quicker attack, less bass hangover and lower cone distortion.

 

Constructed of high-quality MDF and special high-density FMSTM damping material

Regains trunk space by using a very small box size (less than 0.33 cubic feet)

No expensive meters needed to "tune" the enclosure

Very predicatable flat frequency response

Power handling of small sealed box w/ bass of a large box.

Provides detailed bass response, and lower distortion.

Improved transient response versus other boxes designs.

AP Mat enclosures extend lower than conventional enclosures.

Comes with easy to follow installation instructions.

Available for 10", 12" and 15" subwoofers

 

Subwoofer Compatibility

10" Subwoofer Qts of 0.39 or less

12" Subwoofer Qts of 0.45 or less

15" Subwoofer Qts of 0.45 or less

 

[phaze23lbc 10+ year member]

I do have a question for those who know what they are talking about....

Is using "A Periodic Mats" the same as using "Polyfill Stuffing" in an enclosure? And if you don't mind, why?

 

[Johnny Drama 5,000+ posts]

I do have a question for those who know what they are talking about....
Is using "A Periodic Mats" the same as using "Polyfill Stuffing" in an enclosure? And if you don't mind, why?

Yes and no...

Its the same meaning it helps slow down the back wave of the sub. Which in turn makes the sub act like it was in a bigger box.

The Difference is, the poly fill will add ~15-30% gain at best. You will still need a decent size sealed enclosure. It doesnt need to be sealed off from one another.

The AP will only need to be as big as the sub, will require you to seperate the front and back wave. With the hole in the enclosure you can change the amount of fiber to manipulate your results (similar to the polyfill).

 

[jmrunz 10+ year member]

hey guys thanks for all the links and replys. does anybody have any pics of your own ap installs. one last question for now. i have read where people use wire mesh and pink insulation for the mat and usd audio sells mats.

can a porus round disc of styrophome like you get at the crafts department at wal mart work the same with holes drilled through it as an ap mat would work.

anyway i have answered some of my questions myself the ap is supposed to play lower and louder and cleaner with no roll off at louder volumes like sealed boxes have. that is what i want. the mathematics are pretty simple as long as the box is no bigger than the displacement of the sub and both sides are completely seperate from each other.

keep sending me your information. the more the better. you can never know too much.

james

 

[Volenti 10+ year member]

can a porus round disc of styrophome like you get at the crafts department at wal mart work the same with holes drilled through it as an ap mat would work.

james

I doubt it, it has a tendency to squeak, a better option would be open cell foam.

 

[GemaRastem 10+ year member]

yeah, i woulnd't use that foam. I fiberglassed my box, it took a long time. it's quite the undertaking making the baffle and sealing the trunk off from the cab. It's definitely worth it though, hits really really low, sounds great, no boomyness, but isn't extremely loud, probably only a 130ish on the tl with 2 15's runnin at 600 watts, but I haven't had it metered. i love it.

 

[jmrunz 10+ year member]

sounds to me like this is the way i want to go. i spent several hours yesterday looking around the net trying to fund a-p mats for sale and i could not find them. usdaudio.com has them but no way to buy or order through their site. does anybody have a site they know of to order from. i will just use premade mats and build my enclosure around that. going for a mounting board and octogan shaped enclosure around the sub with the mat in the back for 2 12" subs. wish me luck. keep sending ideas though. as it will be a while before i get really envolved in the hard work of this. one article i read though said to use pink fiberglass insulation i think if i can find the mats pre made for the speaker size i will go that way. any suggestions send them my way. thanks.

james

 

[GemaRastem 10+ year member]

I would definitely build my own AP mat, it's easy, buy the stuff at the hardware store, probably cheaper and that way you can tune it a lot easier.

 

[jmrunz 10+ year member]

correct me if i am wrong but by tuning the enclosure you simply make holes through the mat. i realize you dont want to make a hole too big. i have read about the size of a pencil but is a hole slightly bigger than that better than 3 smaller holes. or are smaller holes better. and do you just tune by ear until you like the sound. how did you set your tuning point.

j

 

[jmrunz 10+ year member]

does anybody know exactly how to get a ap enclosure tuned to the right frequency.

 

[Mizah Mar 10+ year member]

here's another link that may help. http://www.audiogearreviews.com/tech/theory/enclosure_design/aperiodic_membrane.asp