Best DIY dampening material for cabinets

lupodwdm · « **on:** 16 Apr 2005, 12:20 am »

So, I'm going to be building a few speakers and I'd rather not spend $50 a sheet for dampening material. In everyones experience, what is the best DIY alternative to line speakers with? I'm going to be using a layer of vinyl floor tile directly against the inside of the speakers, but I need another layer over that to control the actual sound within the boxes. I have been told everything from open cell foam,(the pink stuff at wal-mart), to carpet pads, to lambs wool.

Thanks for the help.

gongos · « **Reply #1 on:** 16 Apr 2005, 12:34 am »

Check out: http://edesignaudio.com/category.php?type=damp They sell great sound dampening stuff--liquid and adhesive.

lupodwdm · « **Reply #2 on:** 16 Apr 2005, 12:37 am »

Thanks for the info, but that's not really what I'm looking for. I already have a high mass layer against the cabinet, but I need something that will trap the excess sound within the cabinet and convert it to heat. Something with a little loft to it.

eric the red · « **Reply #3 on:** 16 Apr 2005, 01:11 am »

Maybe Parts Express has somthing for you. Here's their speaker building page
http://www.partsexpress.com/webpage.cfm?&DID=7&WebPage_ID=29

SET Man · « **Reply #4 on:** 16 Apr 2005, 01:56 am »

Hi there,
May I suggest the Deflex panel? I never use them. But planing to order a pair to put in my behind my Fostex in TQWT cab soon. The design and the material of the Deflex make sense to me and should work well.

http://madisound.com/deflex.html

Good luck,
Buddy

ooheadsoo · « **Reply #5 on:** 16 Apr 2005, 02:43 am »

I've read (somewhere...

) that cotton is excellent stuffing...better absorption coefficients than fiberglass.

warnerwh · « **Reply #6 on:** 16 Apr 2005, 05:17 am »

What's wrong with fiberglass. In Vance Dickason's Louspeaker Cookbook fiberglass did the best next to the acoustistuff partsexpress sells. It's cheap and it works great.

ooheadsoo · « **Reply #7 on:** 16 Apr 2005, 08:09 am »

Was cotton in the Dickason? It might be easier to obtain and work better as well.

Ethan Winer · « **Reply #8 on:** 16 Apr 2005, 12:33 pm »

Lupo,

> I'm going to be building a few speakers and I'd rather not spend $50 a sheet for dampening material. <

I am not a speaker designer, but I've taken plenty of them apart.

Years ago, when I did this, all the acoustic suspension speakers were stuffed with simple fluffy fiberglass. I can't imagine anything less expensive or more effective.

--Ethan

PEB · « **Reply #9 on:** 16 Apr 2005, 12:53 pm »

My advice.

Treatments of any kind are ineffective at low frequency. But bracing reduces the amplitude and pushes the resonance higher in frequency.

Next, bumpy foam attached to the walls helps to suppress standing waves in the midrange and treble. Spray-gluing it in place with 3M #77 helps to make it effective a little lower in frequency.

100% stuffing with poly-fil or fiberglass reduces the standing waves further, while increasing effective box volume slightly.

Attaching anything else to the walls that adds weight but without stiffness only makes things worse. Sorry. This is where the snake oil remedies begin.

$0.02

Christof · « **Reply #10 on:** 16 Apr 2005, 05:36 pm »

I've used the 3 layer sheets from PE, I think called SonicBarrier? and BH#5. The PE version is much cheaper and was very similar to BH#5. I've always used the real wool stuffing from Madisound.

c.

Kevin P · « **Reply #11 on:** 16 Apr 2005, 06:51 pm »

Quote from: Ethan Winer

Lupo,

> I'm going to be building a few speakers and I'd rather not spend $50 a sheet for dampening material. <

I am not a speaker designer, but I've taken plenty of them apart. Years ago, when I did this, all the acoustic suspension speakers were stuffed with simple fluffy fiberglass. I can't imagine anything less expensive or more effective.

--Ethan

We use polyfill from Wal-Mart. It is $2.50 for 20oz. and works about like the fiberglass but doesn't itch as much.

The problem I have with the BH type products is that they are all voodoo and hype. It is supposed to serve two functions.

#1. Dampen cabinet vibrations. Why not just use a thicker cabinet or build it with constrained dampening material? For the cost of BH you certainly could just use a thicker cabinet and brace more. If you use it in an existing design that is ported your are going to be changing the low frequency tuning point by taking up more cabinet volume. You may be causing more harm than good.

#2. Absorb internal standing waves and turn them into heat. I guess it would be logical to do some analysis/measurement. Is the BH supposed to be broadband absorption? If so it would be much more effective is it stood off a couple inches into the enclosure for the same reason that broad band room treatments are spaced off the wall. That is one of the reasons that many use something like rock wool or compressed fiberglass. It can occupy the center of the cabinet where it is more effective at absorbing sound waves and converting them to heat.

Am I overlooking something? Why are people using BH?

Uptown Audio · « **Reply #12 on:** 26 Apr 2005, 07:43 pm »

I like to use a heavy cotton or wool rather than fiberglass. These can be difficult to find though. Fiberglass is a good bet if you can't find any. This is basically shreaded cloth and the only place that I can think of that would have an application other than a speaker manufacturer would be in furniture manufacturing. You might try an home upholstry shop as I believe this is available in "sheets" for use on chair/sofa arms.
-Bill

lupodwdm · « **Reply #13 on:** 27 Apr 2005, 05:02 am »

Well, after looking at what Black hole 5 does, I managed to come up with a DIY solution that I think will work pretty well. I'm laying down a layer of vinyl floor tile agains the walls of the cabinet. (Thanks Danny) Then a layer of 1" open cell foam, then a layer of 1/2" real lambs wool with the skin attached to the back.

In theory, each layer should do the same thing as the BH5, except for a lot less $$$.

Sintz · « **Reply #14 on:** 24 Dec 2005, 08:29 pm »

I've used a building material call "Grace's Ice and Water Shield".
It's an asphalt-based material that's a couple mm thick, comes in rolls (large and small), and has an adhesive side. It's sold for putting down on roofs as an alternative to tar paper and you can get it at Home Depot or Lowes for $40-60 a roll. It cuts easy with a razor blade and is great for deadening any type of panel (internal speaker is what I use it for). The only drawback is that it has a mild asphalt smell that goes away after a couple days.

I origonally used it as an alternative to dynamat in an excessive car stereo installation about 5 years ago, but also treated my entry-level subwoofer enclosure with it to tame cabinet resonances. Works like a charm with minimal volumetric displacement.

Rocket · « **Reply #15 on:** 25 Dec 2005, 12:44 am »

Hi Kevin,

I would also like to find out if bh5 makes a sonic improvement and agree with many of your comments.

As anyone done a before and after comparison. I don't mind paying for the product if it makes an improvement.

Btw i have to get off my butt and some components from you to finish my speaker kit.

Regards

Rod

JohninCR · « **Reply #16 on:** 25 Dec 2005, 04:02 am »

lupodwdm,

You haven't said what kind of enclosure you are building, sealed, BR, RLH, single driver, multi-driver, etc. What type of internal damping is required depends upon many factors and over use of absorbant materials where they aren't needed can "suck the life" out of your speakers, some alignments more than others. Bracing, internal dimensions, shape, diffusors, etc. can go a long to toward eliminating standing waves and reducing reflections back at the driver cones, which are the reasons for damping the interior of a cab.