Damping a cab...

You can cut a 2 X 4" to fit between the speakers on the front baffle and rear baffle and put screws in from both baffles. This is done all the time on many cabinets, especially 4 X 12" cabs.

 

I think the drill is to fill two sides of it like an L with a fluffy substance. I picked up cotton fabric for a 2x12 and started off by lining a thin layer of it all the way around, but it didn't do much. I posted the process here and then someone mentioned the L shape.

I then rolled up a bunch of it and secured it down with staple and wire on two sides (bottom and right). Much better.

As I apply this to all I am learning about room acoustics, this is similar to a bass trap where you'd stack rigid fiber board triangles in a corner from floor to ceiling with a fabric facing to keep them in one place - the low frequencies will build up in corners of a room and make it sound boomy.

I'm sure there's some sort of parallel there.

 

Andy Fuchs uses the material for carpet backing, or used to, and applies it to all of the sides. Not sure about now though

 

I recently stuffed my oversized Lopo 2x12. Love it! The bass is tighter. The mids are more accurate and the highs are slighly dampened-in a good way. Went to a local upholstery place anf bought a big sheet of 3 in thick poly batting.(looks like fiberglass batting but obviously non irritating !) I puffed it up a bit and filled the entire box with it but not too tightly. Supposedly this gives the drivers the illusion of a larger box but with more dampening. I can crank the bass with zero flubbing too. Im using a G12H-30 and G12-65 in the cab. Again Im really digging the results. Bob

 

You might try some Acoustistuff from Parts Express.

 

Adding carpet backing or cotton sheets to a box controls resonance and fools the drivers into thinking they have more virtual cabinet volume (particularly in a closed box). Cheap, easy to install (just takes a staple gun), and you can tune to taste. One side, two sides, etc, add until you are happy.

 

Much cheaper at an uphoslstery store. Was going to get if from PE but the price was too much. The place I went to had both but I opted for the batting so I didnt stuff the back of my speakers! Of coarse if a upholstery store isnt available PE is definately a good choice.


http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-330

..

 

Might help a tiny bit. Try stuffing the cab. Its easy,'tuneable" and easily reversed if you dont like it! Bob

 

The cab works somewhat like a drum, with the front and back panels flexing slightly in and out. If you brace them together you will dampen much of the cab's resonance. The side are comparatively more subject to tension than beam forces and not as susceptible to flexing. Adding a baffle to baffle brace in my large, detuned single 12", cab, made of 3/4" voidless Balti ply made significant difference.

 

I used a common old 2 X 4". It took several skim cuts on the end of the 2 X 4" to get the length exactly right. I would suggest using only method at a time to see dial in the effect you want. Either method can be removed.

 

Theres a big difference between acoustic dampening material, foam and even lining the cab with dampening material. Ive tried all of them. Lining the cab deadened it but thats all it seems.I didnt like it that much. Ripped it out almost immediately.By far (so far) the best (for my ears) is acoustic stuffing. I literally filled the cab with it. Like Fuchsaudio mentioned it "virtually" increases the internal volume while also deadening it. I'd recommend trying both and seeing. I gave up on acoustic lining and such until I recntly tried the stuffing method instead.
:BEERBob

 

Does dampening a cab's resonance create more or less bass?

I recently purchased an oversized 2x12 closed back and even at low volume levels (with the bass rolled all the way off) it still seems to carry through out the building

Is the solution to stuff, add lining and a brace btw the baffels?

 

Stuff it. It reduces bass a bit but also makes it more accurate-less boomy and flubby. If you dont like it experiment with just lining it . Bob

 

loaded question - think of the linear wave example of a frequency. Highs have a short wavelength while low end has a long one. When these waves reflect back upon each other they can create a NULL all the way to nearly creating a doubling effect. It's more prevalent in low frequencies for our ears because the wavelength is longer.

So the reflective sound is cancelled out and we're left with a tighter sounding cab.

This thread's got me thinking about trying a cab completely stuffed with material... Hadn't done this yet. I guess I thought it best to have two sides reflective.

 

The classic formula for cab damping is adding the damping material to the back and 1 of each parallel sides. I agree that it does make a difference but you may not like it. Try any and all methods if you want.
Reinforcing the back or sides is a diffeent issue, but worth doing if the cab has floppy panels.