# Bass traps need some help



## chevy2410 (Dec 29, 2009)

Hi all I'm new to the forum, but have been lurking around for sometime. I'm wanting to add a couple of bass traps to mt HT room and I'm a little confused as to what kind or style to make. My HT room is 11ft from front wall to rear wall and 22ft long with a dog leg to the left at about the halfway point. My wife won't let me go to crazy with acoustic treatments, but would like to look and sound better. So I've made some treatments for my back wall (seating position), using Roxul mineral wool 2" thick and 1'x3' and made 4 of them. That really has help out a lot. Now I want to make some bass traps. Most of the ones I've seen go from floor to ceiling. Is that really necessary? Can I get way with making say something that is like 12"x3' long and place the panel near the top of the wall? I did make a frame that goes from floor to ceiling, that is 12" wide from corner to corner and is cut like a triangle to fit into the corner. Will that design work and how thick does the Roxul mineral wool have to be? I had a link from this forum on the construction of the frames, but can't seem to find it. Anyway thanks so much.


Chevy


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## bpape (Sep 14, 2006)

Welcome to the shack.

Unfortunately, we can't cheat physics. Bass requires thicker panels and more surface area to do the job. When you make them smaller AND thinner, you're cutting your throat twice. 

Chunk style bass absorbers will perform the best with the least amount of space - especially if you're going to limit it to 12" along each wall. Generallyl we do 17x17x24" triangles or 24x24x34" triangles. Floor to ceiling is better than 1/2 of that if you can swing it. I can post a pic of how to give them a nice built in look if you're interested.

Use something like a 2.5-04lb mineral wool and cut in to triangle of the appropriate size and stack them floor to ceiling. It's much easier than back-cutting angles on sheets.

Bryan


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## chevy2410 (Dec 29, 2009)

Thanks so much for the reply Bryan. Yes I would love to see a pic or pics that would be awesome.
_Posted via Mobile Device_


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## lsiberian (Mar 24, 2009)

For bass traps I find the corners to be most helpful. Be careful on the 1st order reflections. I've heard many system that sound better with them so make sure you can try it both ways to get your preference. 

Building a tri-trap in all 4 corners is my favorite way to start off a room.

http://www.gikacoustics.com/gik_tri_trap.html This is what one looks like. It can be built pretty easily and is marvelous for bass control. The next stage is treating the floor to wall corners. This looks terrible in most rooms so I'd just stick to the 4 corners. Most speakers are engineered to perform well in a less than perfect room.


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## chevy2410 (Dec 29, 2009)

I wanted to say that for the acoustic treatments I'm using Roxul AFB mineral wool. now I don't know what pound it is, but I'm wondering if that would be OK for doing like a tri-trap floor to ceiling? Maybe what I should do is post a couple of pics of my room.

Thanks so much for the help so far,
Chevy


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## bpape (Sep 14, 2006)




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## chevy2410 (Dec 29, 2009)

Thanks for the pics Bryan. I have another question that's related to acoustics panels behind my main speakers. I currently have a pair of Paradigm Esprit Bipolar and was wondering if I need to put any panels either right behind them or even up a little higher? Since they are Bipolar should I even put any panels up? what do you recommend Bryan?

Thanks,
Chevy


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## bpape (Sep 14, 2006)

Are they just bipolar tweeters or fully dipole/bipole? 

Some treatment lower behind the woofers could potentially help with boundary issues but you really don't want to kill the tweeter rear wave in most cases as it's probably necessary to maintain response balance. You could use diffusion behind the tweeter though.

Bryan


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## chevy2410 (Dec 29, 2009)

They have both a woofer and tweeter. One set on the front side and one set on the rear side. As far as diffusion goes can you explain a bit? Maybe even post a pic or two.

Thanks,
Chevy


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## bpape (Sep 14, 2006)

OK. If they're full range dipole, then you'd absolutely want to use diffusion instead behind them. One of the big advantages of full rage dipoles is that they tend to cancel bass to their sides, giving them less of a problem with regard to side wall boundaries.

Something like our D1 diffuser fulled with absorption behind would be an outstanding choice.

Here is the page with more information - http://www.gikacoustics.com/gik_d1_diffusor.html



Bryan


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