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Aperiodic Enclosure, anyone tried it?

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nervewrecker
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Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » June 30th, 2012, 12:19 pm

Anyone ever try it locally?

Wanna share some info with the forum-ites or me for that matter?

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Re: Aperiodic Enclosure, anyone tried it?

Postby ruffneck_12 » June 30th, 2012, 1:35 pm

Good question

willing to try it

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Re: Aperiodic Enclosure, anyone tried it?

Postby 3stagevtec » June 30th, 2012, 11:15 pm

I took a brief read on the topic..

I personally don't like it. Seems like it would be difficult to 'tune' and if going sealed, I'd prefer to get the enclosure done right, rather than trying to use the aperiodic design to correct things.

If you looking for increased efficiency, then ported will be the way to go.

(What are the benefits you guys see in using this design?)

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » June 30th, 2012, 11:27 pm

I did a little digging, seems it can be used as an alternative to polyfill when attempting to fit a driver in an enclosure where space is a constraint. Tuning it is the part I am not sure about.

I have to fit a slightly larger than normal driver in a tight spot and I looking at my options. If it fails I can return things to the way they currently are and discard the enclosure (its an experiment).

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Re: Aperiodic Enclosure, anyone tried it?

Postby 3stagevtec » June 30th, 2012, 11:42 pm

I see.. but that seems like trouble to me. KISS as they say..

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » June 30th, 2012, 11:51 pm

Simple went out the window when I decided to build the enclosure with metal and fiberglass. :lol:

I know for a fact it has been mentioned in here before (and the use of it). I hoping maybe someone can cough up some info.

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Re: Aperiodic Enclosure, anyone tried it?

Postby Firewall » July 1st, 2012, 12:19 am

iirc team audionuts has a write up on it. quite a good read to understand the basic concepts and tuning

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Re: Aperiodic Enclosure, anyone tried it?

Postby silent_riot » July 1st, 2012, 6:03 am

Agreed with 3stagevtec.
I also think you won't like the sound, as it tunes out output.
You would need an impedance meter for tuning.

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » July 1st, 2012, 10:39 am

See thats the thing, I dont have an impedance meter :(
I think someone mentioned something of it in here and I demoed that system, it sounded very good to me.
Sealed might be too small, vented I dont really know about in this case, infinite baffle....well thats more or less how it currently is and I am looking for more 'tightness' and a bit more of the 'thump'. A search in here revealed Nigel mentioning something of it in an old thread, I will like to believe its the same application here.

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Re: Aperiodic Enclosure, anyone tried it?

Postby MONGO » July 1st, 2012, 1:07 pm

1.03 - Tuning - checking the resonance frequency
At the resonance frequency of the subwoofer system, the impedance will either peak at its highest level (sealed enlosures), or dip to its lowest level (ported and bandpass enclosures). 6th order bandpass enclosures will have two resonance frequencies, one for each volume.

To determine the resonance frequency of the system, set the multimeter to current measurement, then hook it up in series with the subwoofer to your amplifier, then use the frequency generator to drive the subwoofer. At the resonance frequency, the meter will read the lowest result (sealed enclosure) or the highest result (ported and bandpass enclosures). In the case of the ported and bandpass enclosures, If the measured resonance frequency is not the same as the predicted resonance frequency, adjust the port lengths accordingly. In the case of the sealed enclosure, the resonance frequency can be adjusted by adding or removing stuffing material from the enclosure.

A more accurate version of the above method involves using a resistor in series with the subwoofer system, and connecting the multimeter (set to voltage mode) across the resistor. In this case, the meter will measure the lowest voltage at the resonance frequency of a sealed system, and the highest voltage at the resonance frequencies of the ported and bandpass systems.

From:
http://www.diysubwoofers.org/faq.htm

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Re: Aperiodic Enclosure, anyone tried it?

Postby Brian Steele » July 1st, 2012, 1:48 pm

nervewrecker wrote:I did a little digging, seems it can be used as an alternative to polyfill when attempting to fit a driver in an enclosure where space is a constraint. Tuning it is the part I am not sure about.


I believe an aperiodic alignment is just a lossy vented alignment tuned to the Fb of a sealed alignment of the same volume. The "secret sauce" involves adding resistive material to the vent to flatten the impedance peaks.

So...

1. Start with a small sealed enclosure of volume Vb. Calculate and/or measure Fb

2. Determine a suitable vent diameter for tuning a vented enclosure of the same Vb to the same Fb that results in the vent length being the thickness of the enclosure, so your "vent" basically ends up being a hole in the box.

3. Add resistive material across the vent until the resistance peaks are damped as much as possible. It's best to do this part with something like a WT3, which will allow you to measure the impedance response as quickly as possible.

Don't expect miracles.

Note that there are different variations on the aperiodic theme - I've seen some examples where the entire rear panel of the box is the "resistive vent" - but the main design aim of damping the impedance peaks remains the same.

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Re: Aperiodic Enclosure, anyone tried it?

Postby 3stagevtec » July 1st, 2012, 10:08 pm

^That sounds like fun.. :lol:

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Re: Aperiodic Enclosure, anyone tried it?

Postby SR » July 3rd, 2012, 10:27 am

played with that years ago

it was too time consuming to get correct

used layers of regular speaker box carpet by trial and error over a period of 2 months to get them to perform the way i wanted
this was for a midbass response on doors
i have seen custom built cars with these enclosures for the subwoofer however the membrane was breathing to outside the car aka underneat the trunk which doesnt make it practical for a daily driver
and now with the availabliltly of flat subwoofers this is hardly used anymore

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » July 3rd, 2012, 10:37 am

Sounds complicated but seems one person in here has been getting it right on more than obne occasions as I have repeatedly seen mention of it in his build threads.
Sadly I dont have the equipment (stuff to measure resistance) to attempt this project but maybe one day I will get back to it when I do. It seems interesting.
SR, you ever tried it in the kicks?

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Re: Aperiodic Enclosure, anyone tried it?

Postby silent_riot » July 3rd, 2012, 10:42 am

If you didn't use an impedance meter, it wasn't an aperiodic enclosure, just a leaky box.
Flat subwoofers don't replace AP enclosures.

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Re: Aperiodic Enclosure, anyone tried it?

Postby SR » July 3rd, 2012, 10:51 am

aperiodic enclosure design article based on real world testing by steve head of audio nutz

http://www.teamaudionutz.com/tutorial/1 ... c_Cookbook

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Re: Aperiodic Enclosure, anyone tried it?

Postby silent_riot » July 3rd, 2012, 11:04 am

What did you do to ensure the impedance peak was tamed?

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Re: Aperiodic Enclosure, anyone tried it?

Postby SR » July 3rd, 2012, 11:21 am

absolutly nothing
i tuned by ear and made adjustments to the membrane based on how it responded in the freq range i wanted
and again my use of the enclosure was for mid bass response in a small space not a subwoofer

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » July 3rd, 2012, 11:27 am

I that link you posted was the first one I got via google, I bookmarked it for later reading (have midterms going on).

By 'adjustments' you mean removing layers of carpet/membrane till the right thickness was found? or some other means of varying?

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Re: Aperiodic Enclosure, anyone tried it?

Postby silent_riot » July 3rd, 2012, 8:31 pm

If you haven't dealt with the impedance response of the system, you just have a leaky box.
If it sounded good to you, that is all it was.

nervewrecker, you adjust the thickness until the impedance peak (like in a normal sealed box) is reduced. This reduces output but reduces the boominess of the sound as well.

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » July 3rd, 2012, 11:22 pm

its not for the sub, its for the midbass. :oops:

I was advised they can vent into the cavity with great results though.

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Re: Aperiodic Enclosure, anyone tried it?

Postby silent_riot » July 4th, 2012, 7:22 am

What's the fs of the midbass and the crossover you intend to use?

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » July 4th, 2012, 8:29 am

I dont have the manual for it but I think the fs is in the 70's and I looking at a hpf of either 63 or 50Hz.

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Re: Aperiodic Enclosure, anyone tried it?

Postby silent_riot » July 4th, 2012, 12:44 pm

Double check the fs, because basically if you're crossing the woofer a bit higher than its fs, there's no need for an AP.

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » July 5th, 2012, 11:25 am

I not finding anything for the speakers online, all I getting is the frequency response which starts from 65hz.

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Re: Aperiodic Enclosure, anyone tried it? attempt made

Postby nervewrecker » September 2nd, 2014, 10:06 pm

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » September 2nd, 2014, 10:09 pm



blasted youtube remove the audio because of some copyright drama. sigh

anyone know how to get the audio?

Edit: here is a link from my wall

https://m.facebook.com/story.php?story_ ... =756355374

Sorry for the piss poor quality and distortion from the phone and quality lost with uploading to fb
Last edited by nervewrecker on September 2nd, 2014, 10:34 pm, edited 1 time in total.

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » September 2nd, 2014, 10:29 pm

So I made an attempt. Mistake I see to have made is leaving a gaping hole in the back, it should have been some holes as the membrane (cut up box carpet) keeps flapping around a bit.

Next mistake is using two different speakers so I can't compare response.

Just did some testing to see how much midbass I can dig out of this and where is the sweet spot. Can't make a decision with that gaping hole so it has to be rectified. It sounds best when the vent is faced outside of the cabin (I did a video with it in the corner).

Will do some playing around a bit and see what I get.

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Re: Aperiodic Enclosure, anyone tried it?

Postby Ted_v2 » September 3rd, 2014, 1:09 am

Where u got that instamorph ? Cool product.

Does it get hard or remain soft?

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Re: Aperiodic Enclosure, anyone tried it?

Postby nervewrecker » September 3rd, 2014, 11:06 am

Bought it on amazon.
Gets pretty hard and just put it back in hot water, back to bring soft

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