DIY Bass Trap....Will it Work ? - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 30 Old 01-25-07, 08:47 PM
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Re: DIY Bass Trap....Will it Work ?

Yeah, my riser had terrible effects on the acoustics when I first built it. Nasty "suckout" of a wide region of bass with a pronounced "ring" at certain frequencies.

I added a layer of 1/2" ply over the existing 3/4" and stuffed it with insulation (batting with paper back). Immense change. Much tighter bass, no more boom at some notes, nonexistant at others. I didn't know it at the time, but I was basically "tuning" a big panel absorber.
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post #12 of 30 Old 01-25-07, 09:13 PM
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Re: DIY Bass Trap....Will it Work ?

hey bryan, not to get off track of the original question, but is it possible to place the subs in the riser, sectioning off portions, and insulating? or would that be too much BOOM?

i think i should ask this in the DIY section.

Last edited by scott; 01-25-07 at 09:17 PM. Reason: needs to be in DIY section
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post #13 of 30 Old 05-17-07, 11:20 PM
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Re: DIY Bass Trap....Will it Work ?

There is a DIY Tube Trap posted by Jon Gale. I am not sure how effective it is but I am planning to do two or four to try out. Here is the link. http://www.teresaudio.com/haven/traps/traps.html
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post #14 of 30 Old 05-18-07, 06:52 AM
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Re: DIY Bass Trap....Will it Work ?

Good luck with the tubes. They'll do something. Problem is to get them to work down in real bass frequencies, think 18-24" diameters and then fill them with regular fiberglass at a minimum.

Scott - sorry I missed your question.

Yeah - you can do that - but it presents issues since you can't have it where you have walkway but only under the seats. Then, that can weaken the support requiring additional supports. Don't get me wrong - it can be done - it just needs to be planned correctly from the start.

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post #15 of 30 Old 07-06-07, 05:46 PM
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Re: DIY Bass Trap....Will it Work ?

Hi Scott ,

I'm hoping this explanation helps ...
Membrane bass traps , as per Ethan , rely on the front membrane vibrating , and that vibration being damped in the sealed airgap behind it ....
In the case of a concrete tube , this vibration will be minimal ... for two reasons .
Firstly , be as dense as it is , concrete will vibrate very little ( compared to say plywood ) ...
And , secondly , being of circular shape , it is far less able to flex ...
In a way , the face of a membrane trap behaves as a piston ... Curved concrete couldn't do that .....

My thoughts on Mellencamp's use was that is was an attempt at sound isolation , not absorption ... and the interest in such devices probably a confusion between the principles of a porous absorber ( which a 'tube trap' is .... ) and a membrane trap .... based on shape ...

However , they would make great speaker stands ....

Cheers ,

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post #16 of 30 Old 07-07-07, 08:28 AM
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Re: DIY Bass Trap....Will it Work ?

I think the tube he's considering is just a cardboard form used to pour concrete into - it wouldn't be concrete per se. That said, I still stand by my previous statements and recommend other types of treatment as more effective and taking less space.

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post #17 of 30 Old 07-07-07, 04:43 PM
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Re: DIY Bass Trap....Will it Work ?

Hi Bryan ,

Cheers for explaining a Sonotube .. and I heartily agree with you ...
Would such device act as a ( fairly compliant ) membrane .... like a poly that's a full circle , as opposed to a segment of one ?????
Or a diffusor , with inefficient central absorption ????
In that regard , I'd suggest placing the fibreglass around the inner circumference ... to give it most apparent depth .... But then you might as well use fibreglass tubing , with the foil facing , as per the link a few posts ago ...
However , I'd echo Ethan's , and Bryan's view that a sealed membrane trap would be more effective than a porous device for trapping bass frequencies ... at least you would have the area within abutting the boundary ( the zone of maximum pressure ) , as large as the face , unlike a circular device ....

Cheers ,

Evan .
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post #18 of 30 Old 07-08-07, 09:25 AM
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Re: DIY Bass Trap....Will it Work ?

Let's put it this way - people make DIY Subwoofers out of Sonotube. If it's stiff enough for that, I really don't think it will make a very good absorber. If it does, it would be VERY VERY narrow in the nature of its absorbtion.

Now, if you want to fill it with absorbtion and stick them around the room for some diffusion, that's a more likely use for them - though againm, there are better things to use that would take up less floorspace.

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post #19 of 30 Old 04-13-08, 07:28 AM
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Re: DIY Bass Trap....Will it Work ?

Quote:
bpape wrote: View Post
there are better things to use that would take up less floorspace.
Like what?

I have a room that I am intending to acoustically damp, but for now I only have gotten as far as installing six 5cm thick Rockwool acoustic plates. Now I need something that could help removing cancelation in the 50 to 80Hz area, and something that evens out the mid-bass. My REW graph looks like a very fun rollercoaster from about 90Hz and upwards. And there is one large peak around 46Hz that I would like to reduce a little bit, but that is not the most important issue, because mye SVS SB12+ has this PEQ that allows me to reduce it to about normal level.

I have been thinking of Helmholtz, sandfilled Sonotubes and corner bass traps, but I don't know what will work. Besides, I only have two corners to "use". The room is kind of "L"-shaped, so there is just three corners, and the subwoofer occupies one of them.

I hope someone can answer me politely even though I bring back this old thread
post #20 of 30 Old 04-13-08, 09:22 AM
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Re: DIY Bass Trap....Will it Work ?

Skip the sand filled Sonotubes - seriously.

Do you know what is causing the response abberations? That'll dictate the best way to deal with it and where. What does the decay time look like? That's as or more important than purely frequency response. Potential materials are thick fiberglass with an FSK face or a sealed membrane absorber if it's narrower in nature and the rest of the decay time is in range.

Getting the sub out of the corner will likely help things a lot. While giving the most sheer output, it also unfortunately usually gives the worst frequency response since you're maximally exciting all the room modes by sitting at the end of all 3 room dimensions.

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