# Trap Questions



## Bob_99 (May 8, 2006)

After browsing several forums and reading about bass traps, I was wondering if anyone can answer some of these questions. Some of this may have been discussed in part at other sites but I don’t totally understand the theory behind it.

1. Would a super chunk type of trap or the GIK tri-corner trap work on pressure resistance since the air pressure of the sound going into the trap has no place to escape unlike a corner panel trap which allows the pressure of the air that makes it through the trap to escape from the top and bottom? 

2. Is there a difference in effectiveness between the two types? 

3. Does the effectiveness of either of these traps rely on the sound level? It appears to me that if you’re playing at reference level of 85 Db, then the sound would cruise through the trap much like it does with a wall where at lower levels, the traps would be more effective. 

4. When building a trap, does gluing the cloth to the surface of the panel make a difference? I would think that the glue would stiffen the surface of the fiber making it less able to absorb energy from the sound wave. Would this apply when building super chunks also?

5. Assuming acoustically transparent cloth, does it make a difference if it’s on the surface of the panel or can you place it slightly away from the surface (i.e. 0.5 inch)

I hope my questions are clear and I appreciate any thoughts or ideas.

Thanks

Bob


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## bpape (Sep 14, 2006)

The Tri-Traps are velocity absorbers as are all 'soft' types of treatment. The resistance of the soundwave and cooresponding absorbtion is independent of volume level. It's going to knock down a % of the velocity on the way in and on the way out. It will not act like a pressure absorber.

In general if the fabric is truly acoustically transparent, then where it is in relation to the absorbtion matters not. If it resists slightly, it would be the difference between a damped and undamped membrane.

Bryan


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## Bob_99 (May 8, 2006)

Thank you Bryan. There is still a lot that I need to learn and I appreciate your patience when people must ask the same questions over and over.

Bob


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## bpape (Sep 14, 2006)

No problem at all. Believe me, your questions show that at least you're thinking about it. Some people are just too lazy to do a search. You'd never likely find that kind of thing via a search. 

In all honesty, there is a lot of debate about sealing tops and bottoms of things like this and it can make a difference. One wouldn't think so since it's not a sealed cavity anyway like a membrane absorber or a Helmholz. 

Theoretical acoustics and the science behind it is a huge field where there are still a lot of unknowns as to the why's. Applying that to an in-room situation only makes things even fuzzier. You're not alone. We all still have a lot to learn.

Bryan


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