# bass trap costruction



## chinni123 (Jan 8, 2012)

I am planning to construct bass trap like this which my friend created few days back. He is using 8 feet metal corner bead from home depot to make frame for either bass trap or for absorption panels. Since it is light weight, it is easy to move. The one shown here is for the back bass traps. Since, dipolar speakers are on the wall, he put small metal sheet facing surround speakers to reflect high frequency content. At the end of it he wrapped in 6mil plastic paper and then cloth stapled. Do you have any feeback/concerns on to do like this?

I have following questions.

1. Is it ok to use different size of bass traps for front and back?
2. Is it good idea to use metal corner bead as frame?
3. Any ideas to reflect portion of bass trap that is facing surround speakers?


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## bpape (Sep 14, 2006)

The metal framing is OK.

No problem smaller in the rear than the front - just not different side to side. Just understand the smaller ones won't reach as deep into the bass.

Use some plastic on the face to reflect frequencies from the surrounds. The thicker, the lower it starts reflecting.

Bryan


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## chinni123 (Jan 8, 2012)

bpape said:


> The metal framing is OK.
> 
> No problem smaller in the rear than the front - just not different side to side. Just understand the smaller ones won't reach as deep into the bass.
> 
> ...


Unfortunately, on the back side for one of the corner, we have door, that limits. Other corner in the back can have any size bass trap. 

I am thinking to use same size (17x17x24) in the front and smaller one (need to calculate) on back cornrers. I also put long bass traps on front and back (between these corners). So, it will cover 6 sides of home theater with bass traps.


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## chinni123 (Jan 8, 2012)

What is exactly SBIR effect? For example, front bass traps need to broad band or not. I read article that most sound until 500hz radiates front direction only, so broad band absorption is not needed for front bass traps. But my front speakers are close to wall and I read SBIR effect. I did not understand about it. I will research more.

Appreciate any input.


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## bpape (Sep 14, 2006)

SBIR is when you get interference between direct and reflected sound. The interference can be constructive (a peak in response) or destructive (a dip or null in response). The frequencies impacted are based on the differences in path length. The difference in phase determines the type of interference and the intensity.

Bryan


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