# Can I successfully mod Ethan's traps?



## breeze (Nov 16, 2008)

Ethan, I've studied your bass traps and the installation of them and I have a couple of questions that I hope you can answer before I begin my build:

1. Since I am trying to smooth the bass response down into the LFE range in my home theater, how would your deep bass trap be best modified to use thicker (2 inch or even 4 inch) 705 insulation? Will the plywood 'membrane' need to be thicker, thinner or remain the same? Will the air gap behind it need to be deeper? Can the trap be made wider or narrower for specific installation locations (I already believe they can be made shorter/longer).

2. Is it possible to use a different material for the membrane (say glass or plexiglass) in order to allow the display of movie marquee posters and how will that affect the tuning of the trap. Will another layer of material on top of the plywood membrane affect or diminish it's performance? After all, it is a theater and it is in a house I must share with the rest of the family (esthetics are the issue). I am concerned that the poster paper will 'buzz' and if I add plexiglass or glass over the posters it will negatively effect the trap itself.

Any thoughts you might have on this will be greatly appreciated. I believe you have brought attention to an issue that has long plagued home sound systems and, in general, been ignored. I have finally entered the upper echelon of home sound systems and cannot, in good conscience, ignore this any longer. I want myself and others to hear and feel what this system is really capable of doing...

Thank you for your help.

Oh! One more thing. Is it possible to angle the traps, say 5-10 degrees, from the wall by using different dimensions of firring in order to use the plywood to help break boundary reflections? Again, thanks for any and all input.


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## breeze (Nov 16, 2008)

Maybe if I am less specific of who I ask these questions I might get a response. So, Brian, or anyone else for that matter, can you help me with these questions?


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## Sonnie (Apr 11, 2006)

Hi breeze... and welcome to the Shack.

It may be that bpape can answer you, but it may not be the wisest thing for a competitor to tell someone else how to modify another competitors product. I do not know this for sure, I am just thinking out loud. :huh:

You can always try to contact Ethan... I believe he has a forum as well.


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## breeze (Nov 16, 2008)

I guess I boo-booed. I sent him an e-mail and I thought this was where he wanted me to post--I used his link and all. Anyway, thanks for the reply, and I hope that someone (anyone?) will comment on these panel questions.:scratch::hide:


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## fredk (May 14, 2008)

Breeze. You can certainly modify the traps Ethan has posted plans for on his site. Sonnie, the principles behind the pannel traps is in the public domain so there are not competitive/patent issues. 

This link gives you calculators for various types of traps that can be used to deal with low frequency issues. The site also has a good description of how the different types of traps work.

You can certainly use other materials for a panel, but you would have to know the density of the material so that you can plug that into the formula.

My knowledge on the subject is theoretical since I have not built one of these. If you happen to engage Ethan on another forum, could you pm me, or post here if that is allowed? There is very little practical DIY information out there on this type of trap.


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## Sonnie (Apr 11, 2006)

I do not have a problem with it as long as Ethan does not. :T


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## breeze (Nov 16, 2008)

Thanks guys, I had no idea I would cause any kind of conflict. I think I have most of my acoustic ideas nailed down (way better too much than not enough). I do my corners, both vertical (pack 'em tight, those I can get to), and horizontal. I just have sidewall absorption/reflection issues I was trying to solve in a number of ways. You know, esthetic and sound, at the same time.

I really appreciate y'all trying to help. Can we be more specific about the questions now? :scratchhead:


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## breeze (Nov 16, 2008)

Checked the link and thanks a lot. I know that sounds short, didn't mean to. 

I am not the kind of guy that will spend a lot of time doing calculations and such... I will, however, spend the time to do hardware. I have figured out after a lot of reading that more absorption is better that less. I also know, by listening in my room, that I have some issues having to do with low mids on down. I won't even try to arrange the listening position within inches, nor will I try to tweak a whole list of stuff that no one will ever notice. I will go to pretty great lengths with applied acoustic treatments as long as I can 'modify' them to fit in with my family's lifestyle... I think my goal is not to hunt specific problems, but to smooth overall response so that there is no overwhelming problem (a complete null or a very high peak). 

I bought two subwoofers in order to help combat part of this problem. I have to admit that having Maggies for all channels does complicate the absorption/reflection problem some, tho'. My plan is to deaden the front (even behind the bookcases and the monitor), kill the corners, kill the top corners from the front halfway to the back, kill the top corner on the front wall to the ceiling, low bass absorber in the center back and then try to find a way to mod Ethan's panels for the sides without removing too much of our marquee collection or eliminating the weapon wall:devil:.

I know I am complicated. Everyone thinks so. But it's my own little deception. Laugh along with me while I solve this... I need some info and I don't take anything too seriously (I'm not going to plot out graphs and send 'em or completely change my room just for a few db here or there). I will work all around a few specific generalities:cunning: and smooth overall response by, probably, overcompensating for deficiencies and anomalies. I say overcompensate, then overcome with POWER...:devil:


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## fredk (May 14, 2008)

OK, so I understand, you want to build pannel traps, but not to deal with a specific identified frequency?

Pannel traps are, in general, narrow band resonators used to deal with a specific frequency or band.

If I understand you correctly, it seems like your best bet is a pannel/helmholtz hybrid with lots of damping in it to widen out the absorbtion range (the Q).

Even so, with no idea where to tune the center frequency, you may do more harm than good if it is centered in an area where you have no issues.

Again, I have no practical experience to back this up, but I am pretty sure Bryan will write the same thing.


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