Speaker Box Dampening Material

bluesrx · #1 03-06-2011, 02:51 PM

I've got 2 Carvin RL115 Cabs that are somewhat lacking in dampening material. Looking for a good source for dampening. Also, should all surfaces inside the cab be covered?

Thanks in advnace for any help.

dhomer · #2 03-06-2011, 02:56 PM

Walmart has your solution. Foam mattress topper, probably no more than $15 or so. Generally you cover all surfaces except for the speaker baffle, and don't block/stuff the port(s).

bassteban · #3 03-06-2011, 02:57 PM

My cats climbed into the port of my Flite 2x10, pulled off & dragged out the fiberglass(?)insulation-type stuff stapled to the inside(I saw one actually EAT a bit of the stuff, no lie); I replaced it w/styrofoam sheet packaging, glued to the sides. Seems to work.

seamonkey · #4 03-06-2011, 04:05 PM

Nothing against Walmart, I just don't know how stable over time their mattress pads are.
Parts express sells a lot of options, And I'd trust them more.
http://www.parts-express.com/wizards...TOKEN=97605069

billfitzmaurice · #5 03-06-2011, 04:15 PM

Quote:

Originally Posted by bassteban

My cats climbed into the port of my Flite 2x10, pulled off & dragged out the fiberglass(?)insulation-type stuff stapled to the inside(I saw one actually EAT a bit of the stuff, no lie); I replaced it w/styrofoam sheet packaging, glued to the sides. Seems to work.

Styrofoam is not open celled and should not be used for damping. Aside from not working it also will upset the tuning of the cab by reducing interior volume.

Quote:

Nothing against Walmart, I just don't know how stable over time their mattress pads are.
Parts express sells a lot of options, And I'd trust them more.
http://www.parts-express.com/wizards...TOKEN=97605069

Mattress pads are very durable. How much heavy humping do you think goes on inside a speaker?

Commercial damping materials don't work any better, they're just more expensive. The least expensive material is felt carpet padding, available for free in the dumpster at your local carpet stores.

bluesrx · #6 03-06-2011, 04:51 PM

Quote:

Originally Posted by dhomer

Walmart has your solution. Foam mattress topper, probably no more than $15 or so. Generally you cover all surfaces except for the speaker baffle, and don't block/stuff the port(s).

I've read somewhere to cover the back panel and one of the sides... actually I've heard of a lot of different ideas. So what really is the correct areas to cover.... ? Or is it whatever sounds the best?

bassteban · #7 03-06-2011, 04:53 PM

Quote:

Originally Posted by billfitzmaurice

Styrofoam is not open celled and should not be used for damping. Aside from not working it also will upset the tuning of the cab by reducing interior volume.

Meh. Still sounds fine to me- although according to my wife, my head's firmly planted in my ***.

billfitzmaurice · #8 03-06-2011, 06:43 PM

Quote:

Originally Posted by bluesrx

I've read somewhere to cover the back panel and one of the sides... ?

That notion goes back to the 1940s, when all they considered was preventing internal standing waves. The theory was that you only had to insulate one surface of an opposing pair to stop standing waves from arising. By the 1970s it was realized that the main benefit of damping was to prevent reflections back to the cone, so that being the case everything but the baffle should be damped.
It is possible to overdamp a cab, so you might want to start with just the back. An easy way to test the damping is to stick your head inside the cab through the driver hole and hum, at various pitches. If there's severe resonance at some frequencies you'll hear it.

will33 · #9 03-06-2011, 06:55 PM

Quote:

Originally Posted by billfitzmaurice

An easy way to test the damping is to stick your head inside the cab through the driver hole and hum, at various pitches. If there's severe resonance at some frequencies you'll hear it.

I actually do that in my homebrews. There is only one resonance, low. I'm a bass singer too but approaching 60hz fundamentals is pretty low for a voice. Could it be I'm hitting a harmonic of the tuning frequency (40 - 50hz)? I've never bother to check pitch and reverse engineer this, I just know they go like hell at some certain low note, there are no other resonances above that one.

It's kinda cool but but I've never had a tenor or a chick scream in one to test for high resonances.

The Diaper Geni · #10 03-06-2011, 06:56 PM

Quote:

Originally Posted by billfitzmaurice

Mattress pads are very durable. How much heavy humping do you think goes on inside a speaker?

Is it just me, or did anybody else get the urge to initiate a search on YouTube after reading this?

billfitzmaurice · #11 03-06-2011, 07:00 PM

Quote:

Originally Posted by will33

Could it be I'm hitting a harmonic of the tuning frequency (40 - 50hz)?

No, because the cab isn't tuned to 40-50Hz when the driver isn't blocking that big hole in the baffle. You'll hear resonant modes, which are determined by how far apart the cab panels are. They'll be in the lower mids.

will33 · #12 03-06-2011, 07:05 PM

Aha (light bulb comes on). I thought after I wrote that I didn't account for my head being a cubic foot or so and the open bafflehole so it throws the whole thing off anyway.

Growly Lytes · #13 03-06-2011, 07:43 PM

Quote:

Originally Posted by billfitzmaurice

The least expensive material is felt carpet padding, available for free in the dumpster at your local carpet stores.

I love that....its just what i did. Downunder they call carpet underlay.I got a fare bit for $5 brand new at a carpet store.They had rolls of this stuff.Its brand new but recycled & works good.

wcriley · #14 03-06-2011, 08:00 PM

Quote:

Originally Posted by billfitzmaurice

The least expensive material is felt carpet padding, available for free in the dumpster at your local carpet stores.

How thick should the felt padding be? Several layers built up to be 1" to 1 1/2" thick?

I initially lined my fEARful with automobile carpet padding (found in a dumpster) that was about 1/2 inch thick. It appeared to be made from recylcled cloth fibers. I had second thoughts and added 2 inch fiberglass batting over it.

rpsands · #15 03-06-2011, 08:01 PM

Quilt batting is (IMHO) the best material for this. It's easy to work with, cheap, works well, and can be layered to taste. You can get enough for several cabs for not much at all.

Growly Lytes · #16 03-06-2011, 08:04 PM

I read that fiberglass stuff after a while starts to break down.It ends up shooting out through the ports ,it will make a mess inside the cab & around the inside of the speakers too.

Interceptor · #17 03-06-2011, 08:05 PM

I hate to admit this.

What ever I've got laying around the shop.

Fiberglass, foam packing, polyfill, felt padding, dog toys.

Bill's holler test has much merit.

steamthief · #18 03-06-2011, 08:09 PM

Quote:

Originally Posted by Interceptor

I hate to admit this.

What ever I've got laying around the shop.

Fiberglass, foam packing, polyfill, felt padding, dog toys.

Bill's holler test has much merit.

Best for use with woofers.

Interceptor · #19 03-06-2011, 08:13 PM

Dog toys can size just right for chucking in a fEarful midrange box.

Fritz the Schnauzer really doesn't need to know where his crusty old Monkey went. Shhhh.

billfitzmaurice · #20 03-06-2011, 08:16 PM

Quote:

Originally Posted by wcriley

How thick should the felt padding be? Several layers built up to be 1" to 1 1/2" thick?

Felt is much higher density than foam or poly, so a half inch is enough.