Constraint Layer Damping - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

Reply
 
Thread Tools
post #11 of 17 Old 05-11-10, 10:38 AM
Senior Shackster
 
vann_d's Avatar
vann_d
 
Join Date: Apr 2009
Location: Denver
Posts: 887
My System
Re: Constraint Layer Damping

Quote:
lsiberian wrote: View Post
20 bucks for roofing material is a far cry from the cost of the amps and crossovers.
I'd use Dynamat or a comparable product. It won't smell bad like that asphalt based roofing stuff does.

The treatment should work best if you place it between two layers of equal thickness. That puts the damping material right at the location of max shear in the panel, maximizing effectiveness.
vann_d is offline  
Sponsored Links
Advertisement
 
post #12 of 17 Old 05-11-10, 10:44 AM
Elite Shackster
HTS Moderator Emeritus
 
Anthony's Avatar
Anthony
 
Join Date: Oct 2006
Location: Virginia
Posts: 2,213
Re: Constraint Layer Damping

It's probably not on the interwebs anymore, but back in the 90's when I first got into subwoofer building, there was a guy who would make his own composite panels and then build the box.

Basically it was 3/4" MDF -- roofing felt -- 3/4" MDF sandwich. He would then miter the edges or carefully design a box in a box so that the felt layer was never short circuited by contact with an outer layer of MDF. It was a lot of extra work, but he swore by the damping effects. Not sure what adhesive he used, it's been a while.

I was researching NHT1259 sub designs at the time, might have been the old Bass-list.
Anthony is offline  
post #13 of 17 Old 05-11-10, 10:44 AM
Senior Shackster
 
vann_d's Avatar
vann_d
 
Join Date: Apr 2009
Location: Denver
Posts: 887
My System
Re: Constraint Layer Damping

I've also thought about using honeycomb sandwich panel construction but the cost seemed to outweigh the benefits. Maybe a foam core sandwich panel could be constructed DIY and really help reduce the weight of the cabinets while maintaining excellent panel stiffness. The foam core may act as a damping material in the process.
vann_d is offline  
post #14 of 17 Old 05-11-10, 02:08 PM Thread Starter
Elite Shackster
 
lsiberian's Avatar
lsiberian
 
Join Date: Mar 2009
Location: Fort Worth, TX
Posts: 2,625
Re: Constraint Layer Damping

Quote:
vann_d wrote: View Post
I'd use Dynamat or a comparable product. It won't smell bad like that asphalt based roofing stuff does.

The treatment should work best if you place it between two layers of equal thickness. That puts the damping material right at the location of max shear in the panel, maximizing effectiveness.
Peel-n-seal is what one of my friends uses. The exterior structure will be 3/4" plywood and quarter round on the edges to help with baffle step and make finishing quick work. I'm quite sure this is overkill, but that's the point of this build.

Constraint Layer Damping, A bracing matrix and thick Rockwool treatment is more than my current speakers have.
lsiberian is offline  
post #15 of 17 Old 05-16-10, 12:14 AM
Senior Shackster
7
 
Join Date: Jan 2008
Posts: 790
Re: Constraint Layer Damping

Quote:
lsiberian wrote: View Post
http://www.silcom.com/~aludwig/Louds...ration_damping has a very good article on the subject and suggests using 30 lb. roofing felt.

I'm wondering if any of you have experiences with constraint layer damping in loudspeakers.

The gentlemen measured a 20db decrease in panel vibrations which I found impressive.
I remember the old Ludwig build, but hadn't read it in ages. My first thought reading your initial post was 'what the is 30lb roofing felt?'. Turns out we have a similar product here called Malthoid dampcourse which is about $A13 for a 100mm wide 20m roll so I think I'll give some a try in the speakers on the interior walls. Not sure what to glue it to the walls with though. I've emailed and enquiry over the w/e and hope I'll get a response.

Vann's post 2 is my understanding of CLD (better expressed too).

Quote:
vann_d wrote: View Post
I've also thought about using honeycomb sandwich panel construction but the cost seemed to outweigh the benefits. Maybe a foam core sandwich panel could be constructed DIY and really help reduce the weight of the cabinets while maintaining excellent panel stiffness. The foam core may act as a damping material in the process.
Many years ago, about the time of the SL600 Celestions, a friend built some speakers and subs with a Styrofoam core and Laminex skins. It was very light and stiff and seemed to work well but we had no way of measuring back then. Each skin was added over the 50mm thick styro and left to dry. Panels were cut and mitred and glued to each other to form the enclosure. The baffles had marine ply behind the drivers to give extra support.
The speakers were huge, a big 4 box sort-of line array a la Infinity IRS.
Lucky7! is offline  
post #16 of 17 Old 05-16-10, 07:11 AM
Shackster
Syd
 
Join Date: Jul 2008
Location: 26147
Posts: 58
Re: Constraint Layer Damping

Quote:
I'm wondering if any of you have experiences with constraint layer damping in loudspeakers.
Lots of DIY stuff.
Found the roof felt too cumbersome and difficult to work with.
I also tried the layer technique in SpeakerBuilder 3/89 of layering veneer plywood with drywall sandwiched in between. Again cumbersome and difficult.
Another article in SB 5/96 ( Hajo Prodan "The Opposite Moduli(OM) Speaker Cabinet" ) lead me to OM compounds and try laminating layers of plywood with silicone RTV.
While messy to work with it created panels that were much more inert than layered ply.
On my later subs I did not want to resort to a layered "brute force" technique, so I made an acoustic mud compound to grout on the inside of the sub panels.


Syd
Syd26147 is offline  
post #17 of 17 Old 05-20-10, 03:14 PM
New Member
gerard
 
Join Date: Feb 2007
Location: canada
Posts: 2
Re: Constraint Layer Damping

Yoo All

Currently building curved speakers using 1/6" sheets of PVC bonded with Neoprene to a thickness of 3/4"
Best enclosures I have build in 30 years of building
Cheers
Sunny
sunnyduce is offline  
Reply

Bookmarks

Tags
constraint , dampening , layer

Quick Reply
Message:
Options

Register Now




PLEASE COMPLETE ALL REQUIRED FIELDS BELOW... THANKS!

REQUIRED FIELDS ON THIS PAGE
YOU MUST COMPLETE ALL OF THESE

Username
Password
Confirm Password
Email Address
Confirm Email Address
Random Question
Random Question #2




User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
PLEASE READ BELOW PRIOR TO ENTERING AN EMAIL ADDRESS!

ATTENTION!

YOU MUST ACTIVATE YOUR ACCOUNT!

Activation requires you reply to an email we will send you after you register... if you do not reply to this email, you will not be able to view certain areas of the forum or certain images... nor will you be able download software.

AN INVALID EMAIL ADDRESS WILL CAUSE YOUR ACCOUNT TO BE DELETED!

See our banned email list here: Banned Email List

We DO NOT respond to spamcop, boxtrapper and spamblocker emails... please add @hometheatershack DOT com to your whitelist prior to registering or you will get nowhere on your registration.


Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML is not allowed!
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


For the best viewing experience please update your browser to Google Chrome