Hello Ethan
I´ve read a lot about yours traps but i have a doubt
I n my room there is a 12mlm (1/2 inch) dry wall mounted over a wooden frame filled with fuflly fiber glass,covering a brick wall.
I want to install yours membrane traps.
I think to use the 12mlm existing dry wall, for the trap´s back.
Is the 12mlm thickness enough for the back. Do you think it will work ok?
Any more advice?
Thanks!!

That's probably thick enough, but I usually suggest fiberglass bass traps for most rooms. How big is your room?

--Ethan

Hello Ethan and thanks for answering.
My room is 17 foot wide (5.20mts) by 23 foot long (7 mts aprox)
I´ve tried broadband fiber glass, but the room is to dead.It sounds nassal. the ceiling is a big broadband fiber glass absorver.
You have seen my projet before at this link:( I think)
(http://www.johnlsayers.com/phpBB2/viewtopic.php?t=10195&highlight=)
I´ve just begin to redesing.I think yours membrane trap will give to my room low absortion and life .
Do I´m wrong?
Sorry about my english!! I speak spanish.

12mm drywall should be fine, i prefer using 5/8 (16.25mm). Do not forget to make your basstrap airtight. Anyway, ive look the picture of your project and you sure need bass trapping. I fear that with your wall design, the upper frequencys would be dead and leaving the bass uncontrolled. You have to control the reflection on mid and high, the only case where you can put as much as you can is for bass trapping. The goal is to make the reverberation time pretty much the same on all the frequencys band. You have a nice studio and the mode look pretty good, it can be wonderful for sure!

What do you mind? the old project or my new desing?

If you cover corner bass traps with paper or thin cardboard that will reduce absorption at mid and high frequencies, and actually increase absorption at bass frequencies. Of course, you don't want to do that for panels at reflection points, or at other places where you really do want broadband absorption.

--Ethan

`If you cover corner bass traps with paper or thin cardboard that will reduce absorption at mid and high frequencies, and actually increase absorption at bass frequencies`

how does the mechanics work that it increases absorbtion at bass frequencies? how can this work?

thanks

i believe the cardboard serves as a membrane which vibrates, and that vibration is then damped by the rigid fiberglass it's bonded to.

--Ethan

makes sense.

does the cardboard or paper need to be glued to the fibre glass?
thanks again

Yes, either glued, or pressed tightly in a frame etc. At least I think so. I never actually tested it both ways.

--Ethan

thanks.
would something like sound barrier mat (the dense stuff) do a similar job .

no idea.

how thin does the cardboard need to be?

would this do a good job ?
http://www.screwfix.com/prods/19574/Deco...-Roll-2m-x-50m#

I've used thin cardboard and thick shipping box cardboard. Both pass bass well.

--Ethan

thanks ethan