Adhesive/materials for Constrained Layer Damping

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Need some input on constrained layer damping for a 9'x20' (wall sized) panel...

There are at least two different approaches, one here:
Multi-layer damping
This seems to be similar to the roofing felt approach often mentioned but, since very high sheer strength may be important, what is the best adhesive to use with constrained layer(s) of roofing felt? Contact cement?

and another approach here:
Single component - Green Glue
Easier to implement, but is performance compromised?

For frequencies below 100Hz, which option provides better damping and isolation?

What other alternatives should be considered?
 
I am in the process (testing at the moment) of building some monitors out of steel.
Have used a layer of rubber inside (see pic, only shows when was being fitted). Seems to be working, not sure if used with something else than steel...

Any thoughts or comments?
 

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Paul - you might find this useful - maybe - got $$$$ ?
http://www.soundproofing.org/infopages/flooring.htm?gclid=CITp6IrygJACFVB1OAodbly3ug

Here is another line to some adhesive http://www.quietsolution.com/html/quietglue.html

and Soundproof wood (along with some articles and tips to read.) http://www.quietsolution.com/html/quietwood.html

Soundproofing drywall - http://www.quietsolution.com/html/quietrock.html

and some information for CLD - Constrained Layer Damping
http://www.audioholics.com/educatio...ering-mechanical-noise-floor-in-speakers-pt-2

I haven't had a chance to try any of these materials so I can't vouch for them. I did see a submarine that had like about 6 inches of rubber (I'm guessing) coating it's hull - and that was supposed to quiet things down real well!

:cheers:

BTW - almost forgot --- Neoprene rubber - either solid sheets or glued together layers can work well. Grab some old truck or tractor tire inner tubes - cut to fit - glue as required - should work. You can buy the stuff on xbay but it's so darn heavy that the shipping cost will kill ya.
 
Hi Paul,

I have used green glue for a few small scale projects (speaker related)
and feel pretty confident that it is an effective damping solution.
Roofing felt and other materials are often mentioned as constrained layer damping materials but has anyone ever measured their effectiveness?
Green Glue has had plenty of independent tests done to back up their claims. Probably it's main attraction for sound isolation is that it is effective at damping the main resonances of sheet rock walls thereby increasing sound insulation at <100hz.
However it ain't cheap 180 sq ft would take 18 tubes, a couple of hundred bucks.
What is this panel, and what are you trying to achieve?
If it is for sound insulation It would be useful to have a good look around the greenglue site or some of the home studio building sites and forums. sub 100hz sound isolation doesn't come easy and getting small details right is essential.
good luck
Khush
http://forum.studiotips.com/viewforum.php?f=1
http://www.johnlsayers.com/phpBB2/index.php
 
Paul W said:

Need some input on constrained layer damping for a 9'x20' (wall sized) panel...

For frequencies below 100Hz, which option provides better damping and isolation?

What other alternatives should be considered?

Hi,

It is not obvious at all what you are trying to do. If you want acoustic
absorbtion or acoustic isolation are two entirely different matters.

At frequencies below 100Hz its hard to see the relevance
of constrained (or for that matter restrained) damping.

:)/sreten.
 
Hi sreten, do you mind to explain?

To my small understanding, the CLD walls absorb low frequency energy, so they stop the waves from going through and from reflecting back into the room. That would mean, that absorption of waves in the room and isolation for waves out of the room are both achieved.
 
MaVo said:
Hi sreten, do you mind to explain?

To my small understanding, the CLD walls absorb low frequency energy, so they stop the waves from going through and from reflecting back into the room. That would mean, that absorption of waves in the room and isolation for waves out of the room are both achieved.


Hi,

For soundproofing a wall CLD has some advantages but this will barely
affect the acoustics inside the room. If anything for example damping
a drywall that has absorption in the bass will reduce this absorption.

However what does a 9' x 20' panel actually mean ? free standing ?
on a wall ? what type of wall etc. and what is it wanted to do ?
affect room acoustics ? provide soundproofing ?

:)/sreten.
 
More info... The project is a wall sized baffle for sealed subwoofers, with sub-enclosures for LCR main speakers. The objective is to help reduce stored energy radiated into the room to an absolute minimum.

Building the baffle to be very stiff is no problem as extensive bracing will be implemented, including bracing directly to a solid concrete back wall. The current plan is to build the subwoofer portion of the baffle without damping, but make it stiff enough to ensure baffle resonances are well above the subwoofer range. The LCR sub-enclosures are more likely candidates for CLD, but I thought the subwoofer portion of the baffle should be considered while in the planning phase.

The main subwoofer baffle will likely be used for at least 10 years, so I want to build it correctly, and build it only once ;) .

The test phase will be short so I want to limit sample testing to those most likely to succeed...which is why I need to know the proper adhesive for the roofing felt approach.
Thanks,
Paul
 
I have done a lot of walls with CLD. I always used Liquid Nails for Subfloors. The subfloor variety is important because it does harden, stays pliable. This does an excellent job and is readily available. Three small tubes per 4 x 8 sheet is about right.

Construction details can be found in my book on Home Theater.
 
Green Glue and CLD

I am (trying) to build a CLD cabinet laminating with Green Glue. I layed up my panels yesterday, but this stuff takes forever to dry.

It's like sticky green snot...does anyone have an idea as to how long it will take to be workable between panels for box construction? (stable and dry?)

Chris
 
Hi Chris,
Green glue doesn't dry and is not usable as a glue despite the name, the surfaces will stay together as it is very tacky but will creep under load.
I just used 18 ga brads from a nail gun to hold the panels together a few screws will do. don't use too many or you'll bypass the damping layer.
Green glue is not the easiest stuff to use, it's a pain to clean off but is the most effective damping system I've used.
I'm sure you'll be pleased with the results
Good Luck
Khush
 
I recently changed the CLD material that I use to polyurethane. They is a type of poly that is elastic but very strong and mostly rigid. It bonds very well and dries very fast, since it is a two part. It provides a strong yet flexible and well damped joint. No nails or screws required. There are multiple places to get this material. Just make sure that it is the elastic and not the rigid form of poly.
 
chrismercurio said:
Earl,

Do you say which you use?? I'll will try it next time instead as long as it works for cabinet construction.

Thank you,

Chris

I tried to look up the exact company, but couldn't find it. Just google polyurethane reson and you will be baraged with choices. When you find one that looks good post it and I'll critique it.


454Casull said:
IIRC, the effectiveness of CLD goes up as the adhesive layer decreases in thickness.

This is not wholy true. The ideal youngs modulus and thickness of the center layer depends on the stiffnesses of the skins. The effectiveness drops substantially if the two skins are not the same stiffness. This is a common mistake.
 
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454Casull said:
IIRC, the effectiveness of CLD goes up as the adhesive layer decreases in thickness.


Mine wound up less than 1mm thick. The beauty is that the silicone strongly adheres the panels together, so all you need to do is apply light clamp pressure after you squirt on a few beads of the stuff.
 

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