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Aperiodic Enclosure, anyone tried it?

(I.C.E.)In Car Entertainment - Mobile Audio and Video

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Re: Aperiodic Enclosure, anyone tried it?

Postby Ted_v2 » September 3rd, 2014, 11:25 am

Leaves a oily residue?

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » September 3rd, 2014, 11:27 am

Nope, nothing. I does throw it in a Pyrex bowl with hot water and it gets clear and soft


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Re: Aperiodic Enclosure, anyone tried it?

Postby nigel1977 » September 3rd, 2014, 12:03 pm

is it drillable/machinable when hard?

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » September 3rd, 2014, 12:09 pm

Yup can be drilled, machined, sanded etc.
Cut some slits with my dremel and drilled 4 holes in the back to put nut and bolts to secure a removable back plate unto it allowing me add and remove layers of box carpet.
Only downside is if you drill or cut one spot continuous the generated heat tends to get that area slightly soft like rubber. Hardens a few seconds after you stop. When I drilled the holes some debris got in and got hard, wasn't difficult to get out when I push the bolt through. Only the immediate area being machined gets that way from the friction, rest of the structure remains hard and keeps its shape.
If you go wrong soak that area in hot water and change the shape or add more material.

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Re: Aperiodic Enclosure, anyone tried it?

Postby nigel1977 » September 3rd, 2014, 12:35 pm

Im having a hard time trusting anything that softens with hot water.



Are you going to fiberglass the finished product, or is the instamorph the final product?

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » September 3rd, 2014, 2:35 pm

Actually is just an experiment to see if I like or come even close to liking the results. Too much variables as is to say yay or nay but it it does yield anything close to OK in my book I'm willing to try a sub in a fiberglass box.

I'm only using the plastic for a quick mock up. Comes in handy for such instances or to make / clone a template that it in a hard position to access. It's strength is in no way close to that of fiberglass. I don't see it being used as a finished product where strength is a concern.

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » August 16th, 2015, 3:04 pm

https://youtu.be/lF9hOrcYQAE

So I had this sub sitting around and decided to try a little experiment with it.
It's noisy at the membrane. Is it usually like this or more compression / more material needed?

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » August 16th, 2015, 3:33 pm

https://youtu.be/3QbcAuTFz1o

This is how it sounds outside the vehicle.
Only a matter of time before YouTube removes the audio

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » August 16th, 2015, 3:35 pm

https://youtu.be/tcTpmMLqT_8

More of it, hurry before the audio is removed due to copyright

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Re: Aperiodic Enclosure, anyone tried it?

Postby ruffneck_12 » August 17th, 2015, 5:44 pm

how does it sound to you?

Video wouldnt give an accurate account unless you have a good mic

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » August 17th, 2015, 6:13 pm

Sounds average on average music. It was crossed at 50hz -12db slope and no subsonic filter.
You can get a decent thump out of it but from the medium 30hz notes the cone movements seems hampered from apparently too much material or too compact. I'll try removing some material or adding more and having it less compact.
Air is leaking from the sides as well so there needs to be sealed off in order to make sure all air travels across the membrane.
It's just an experiment to see what I can get out of it. Ideally the enclosure supposed to have the membrane in the back, front or iirc both. It supposed to separate the rear and front waves so I'm not expecting a miracle.
And of course, losses as its very inefficient. My 10" in a sealed box is louder.

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » August 23rd, 2015, 12:14 pm

Well, kept it in the truck all week to see what differences I hear. It does not go as deep due to cone excursion being inhibited.
Today I took out a few layers and experienced with the screws to compact and loosen material. Got some decent controlled excursion which was acceptable. The one main handicap is lack of cabin gain because the sub is in the cabin.
Took it out and installed it in the car. Sounded a lot better but the deepest of deepest notes barely there. Could very well make for a daily system to listen music on.
Will see what I can do with it in time to come.

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Re: Aperiodic Enclosure, anyone tried it?

Postby ruffneck_12 » August 23rd, 2015, 11:03 pm

noice, it have any programs that can simulate this?

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » August 24th, 2015, 5:51 am

Right now is trial and error.
Bass a little loose on it and not hitting the deepest of the deep so I'll add back some material a little less compressed.
Haven't done and impedance test as my dmm can't accomplish such. Need something like a fluke.

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » May 17th, 2020, 10:17 pm

So it's been years since I even contemplated anything like this.

Have an IDQ 12 D4 hanging around that I got from the local MECA rep. Decided to fool around with it.

I used polyfill as the membrane and have 5 bolts that a vented backplate can slide back and forth on to compress or decompress the polyfill to restrict or allow air movement across it.

The back of the enclosure has two pairs of circular 2.5" holes I cut with my hole saw and a wire mesh to keep the sub from pulling the material in.

If you notice a double baffle I had screwed up the hole for the sub as my morning coffee had not registered yet. Got a piece from our area box specialist Riyad from Spectro customs and cut a new hole.

Initial tests show that I need more vent area as the cone movement is restricted too much. You compress or decompress you just get more thump or a looser thump. There is some low end response but nowhere near enough without audible distortion.

Double the vent area and quite possibly longer studs if needed may be options.

Something I will revisit in my spare time now that I have a good template.


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Re: Aperiodic Enclosure, anyone tried it?

Postby ruffneck_12 » May 31st, 2020, 11:02 am

a man of science bai

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Re: Aperiodic Enclosure, anyone tried it?

Postby image91 » July 19th, 2020, 7:36 am

Good stuff nervewrecker. Heard a pair of 6" subs in front doors using the aperidodic enclosure design. Sounded great in my opinion. A concept I would like to employ at some point. Nice to see stuff like this

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Re: Aperiodic Enclosure, anyone tried it?

Postby Brian Steele » July 22nd, 2020, 12:48 am

I think to get the best results, you may need to tune the "vent" to the Fb of the driver in the box (sealed), and then stuff the vent until the impedance curve is as flat as possible. Or something like that. Easier to do with DATS or an impedance measuring jig that you can use with REW.

Oh, and Hornresp can be used to sim this type of alignment.

BTW, I've got a DATS v2 for sale if anyone wants one. I got me the V3 version a few months ago. The V3 version provides a few more features, but the V2 version is smaller and more portable (easy to toss in a laptop bag with a laptop for example)

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » July 26th, 2020, 12:51 am

Brian Steele wrote:I think to get the best results, you may need to tune the "vent" to the Fb of the driver in the box (sealed), and then stuff the vent until the impedance curve is as flat as possible. Or something like that. Easier to do with DATS or an impedance measuring jig that you can use with REW.

Oh, and Hornresp can be used to sim this type of alignment.

BTW, I've got a DATS v2 for sale if anyone wants one. I got me the V3 version a few months ago. The V3 version provides a few more features, but the V2 version is smaller and more portable (easy to toss in a laptop bag with a laptop for example)


Thanks for the advice, its valuable advice for me if it came from you.

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Re: Aperiodic Enclosure, anyone tried it?

Postby Brian Steele » July 26th, 2020, 5:32 pm

If you really want to try something different, have a look at passively-assisted sealed alignments. Basically you take a sealed Q~1.0 enclosure and put a good deal of capacitance in series with it. End result is a frequency response that's close to vented, without the vent. Box is small though, so you lose some efficiency (no free lunches here). Looks like a good match for cheap car audio subwoofers with their high inductance, but you'll have to model with Hornresp to determine what size box and the amount of capacitance needed to get the best results from a particular subwoofer.

20200710-1227W-cap.png

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Re: Aperiodic Enclosure, anyone tried it?

Postby ruffneck_12 » July 31st, 2020, 9:50 am

Brian Steele wrote:I think to get the best results, you may need to tune the "vent" to the Fb of the driver in the box (sealed), and then stuff the vent until the impedance curve is as flat as possible. Or something like that. Easier to do with DATS or an impedance measuring jig that you can use with REW.

Oh, and Hornresp can be used to sim this type of alignment.

BTW, I've got a DATS v2 for sale if anyone wants one. I got me the V3 version a few months ago. The V3 version provides a few more features, but the V2 version is smaller and more portable (easy to toss in a laptop bag with a laptop for example)



What does the v3 have besides the cool looking terminals?


Also you thought no one would notice you changed your avatar huh? :wink:

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Re: Aperiodic Enclosure, anyone tried it?

Postby Brian Steele » July 31st, 2020, 5:09 pm

V3 has detachable leads (and USB cable), a built-in resistor for re-calibration purposes, and can do measurements at different voltage levels. It's built more like a lab device. It's a nice piece of kit, but if you've got a working V2, I'm not sure it's worth the cost of the upgrade, unless you really want any of the above-mentioned features.

You only now notice the change to my avatar? :-)

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