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Author Topic: MLV as membrane behind basstraps  (Read 9898 times)

Offline kimgul

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MLV as membrane behind basstraps
« on: February 21, 2012, 09:59:40 pm »
Hello to the masters of acoustics!

After lots of searching and reading (thank you ethan and many others) I have done what I can to my little controllroom to make it sound the best. Lots of basstraps in corners and covering the reflectionpoints etc, but I keep wondering: what next to make it better?

Some people talk about membrane behind basstraps to vibrate and turn the lowest frequencies into heat. would something like:

behind a rockwool basstrap make the room better?
My traps today has no membrane, just thick Rockwooltraps.

Having a big dip around 75 and some +3db peaks around 300 and 500..

Best regards from Norway

Offline kimgul

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Re: MLV as membrane behind basstraps
« Reply #1 on: March 24, 2012, 06:54:02 pm »
No replies, so I`m guessing no one have tried it! :( Guess I`l save my money then...

Offline Treelady

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Re: MLV as membrane behind basstraps
« Reply #2 on: March 27, 2012, 01:15:22 pm »
The  CURVE's by Acoustic Geometry have some sort of MLV behind them, and they work really well.  Of course, they were designed by those who know better about such things, but I like them.

(I am not affiliated or related to them, just to be clear)
Garrett Haines
Chief Mastering Engineer, Treelady Studios, Pittsburgh, PA
Senior Contributor, Tape Op Magazine

Offline Syncamorea

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Re: MLV as membrane behind basstraps
« Reply #3 on: September 10, 2012, 08:35:51 am »
Most of the designs I've seen used an enclosure that is sealed on all but one side.  The rock wool or fiberglass is held in place by a net or string and the MLV covers the open side of the enclosure.    The netting keeps the rock wool from contacting the membrane.  You should not stretch the membrane.  One method I've seen is to lay the MLV on a flat surface, put an adhesive on the edge of the enclosure that will contact the MLV, then lay it on the MLV until the adhesive cures.  You can then trim any excess MLV and possibly add some tacks or roofing nails to make it durable.  I have also seen rock wool on both sides of the membrane, again constrained so as to not touch it.
Is there an echo in here?

Offline franman

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Re: MLV as membrane behind basstraps
« Reply #4 on: March 15, 2013, 07:22:54 am »
Great topic guys.. Most of what has been said about implementing the MLV style membrane traps is inline with how we use them. Also note that (as Thomas said) large areas are required when using these types of traps. 2'x2' areas are not going to have any significant affect. We typically do large wall and ceiling surfaces when these types of solutions are indicated.
Francis Manzella
President - FM Design Ltd www.fmdesign.com
Managing Director - Griffin Audio USA www.griffinaudiousa.com

Offline Jim Williams

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Re: MLV as membrane behind basstraps
« Reply #5 on: April 13, 2013, 01:20:38 pm »
I would consider any active electronic device between the monitor path and power amplifier to be an additional filter. The end user must decide if the improvements are worth the losses incurred.

Back in the mid 1990's I was working in a larger dual SSL facility in the Caribean. The owner had installed an expensive, famous "English" 4x10 system, soffet mounted. A BSS stereo crossover was used, modified for the crossover frequencies.

I was wondering why the playback was so muted, a total lack of low level high frequency details. After reworking the entire room, I asked if I could take on that playback as I was not hearing the results I got in other rooms.

Several decent film caps, a bunch of excellent opamps and the removal of low end electrolytic coupling capacitors changed everything. The owner needed proof so I only reworked the right side.

Then that tired old boring, sinking ship movie sound track was played. Next a bell tree pops out on the right side, nothing out of the left. The owner looks suprised and says, "what's that?"

I say, "that's the music your playback system and it's designer think you don't need to hear".

"Can you do the other side now?"

For simple 2 way systems I prefer an passive solution using the finest air foil inductors, wirewound precision resistors and premium exotic film caps. The parts are very expensive, however. I have the same amount invested in the crossover parts as I spent on the speakers new. It was all very worthwhile.

Offline bruce741

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Re: MLV as membrane behind basstraps
« Reply #6 on: December 07, 2013, 01:59:33 am »
We typically do large wall and ceiling surfaces when these types of solutions are indicated.
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