Looking for the best Foam for internal damping of a bass cabinet. Any recommendation?

Your going to hear a lot of opinions on this one but the universal one will be that the best solution will not be a foam fill. A fiber fill will give better results and the fiber with the best damping will be fiberglass. I know many don't want to use it so the next option is usually some type of synthetic such as a polyfill fiber that is usually available at many craft or upholstery shop for pillow stuffing. You won't have to use gloves when handling it and it doesn't produce the dreaded fiberglass particles that can exit through a port. In a closed enclosure it is not a real problem however.
 
So rockwool could be it

No, the best is long strand alpaca wool from Bolivia. That's a natural fiber. Way beyond what is necessary unless you win the lottery.

Rockwool is made from Basalt and is similar to fiberglass only less hard on your lungs, more stable of a fiber and better at damping.
 
I hate to be a wet blanket, but I will .....

I think you first need to ask why is any stuffing/material required in a woofer cabinet.

One school of thought is that you need to attenuate/absorb the back wave from the woofer. The second school of thought is that the stuffing will make the cabinet "behave" as a cabinet with a larger internal volume.

IOW, what are you specifically trying to accomplish.
 
I hate to be a wet blanket, but I will .....

I think you first need to ask why is any stuffing/material required in a woofer cabinet.

One school of thought is that you need to attenuate/absorb the back wave from the woofer. The second school of thought is that the stuffing will make the cabinet "behave" as a cabinet with a larger internal volume.

IOW, what are you specifically trying to accomplish.
I want to attenuate the back wave and reduce as much as I can the vibration in the cabinet.
 
Murphy,
I would take a multipronged approach to this. First of all make the cabinet walls a stiff as is practical with not only thickness but also bracing tying the walls together. Space the bracing so that you have different surface areas by not splitting the walls evenly say up and down on the side and back panels. This will help to distribute the frequencies emanating from any surface. Then use the rock wool or what ever on the walls to help damp them further and help absorb some of the reflective waves. As a final move add some loose fill fiber to attenuate further the high frequencies and any mid range that can be attenuated. Low frequencies are out to the question so just forget about trying to attenuate those.
 
No, the best is long strand alpaca wool from Bolivia. That's a natural fiber. Way beyond what is necessary unless you win the lottery.

snip

Or from Australia ! I have Alpacas (and sheep) and, yeah, the wool is marvellous. You need long staples and the prep is quite different from sheeps wool. I do recommend it as worth a try if you can get some. The length of the fibres, or the thickness of the felt or mat, is important to the LF performance, unsurprisingly.

I had hoped to market a semi-commercial DIY product made from it but the missus uses most of it to spin and it's an effort even to scrounge enough for my own products.

When we retire from the Post Office we might look into expanding the flock and maybe the product will become viable. OTOH, Mrs. blakkshepe may just make hats and scarves out of the extra.....

Rgds,
blakkpakka
 
I want to attenuate the back wave and reduce as much as I can the vibration in the cabinet.

Well, in that case, use bracing to reduce cabinet vibration.

As far as reducing the backwave from the woofer, you will have a basic difficulty. Absorbtion will need to be comparable in size to the wavelength (1/4 or larger to the wavelength). At 100 Hz, the wavelength is about 11 feet and at 500 Hz it is still about 2 feet. Your cabinet is not that large. This is a basic problem with this strategy when appplied to woofer cabinets. Now there may be other reasons to add material, but that is another issue.
 
Well, in that case, use bracing to reduce cabinet vibration.

As far as reducing the backwave from the woofer, you will have a basic difficulty. Absorbtion will need to be comparable in size to the wavelength (1/4 or larger to the wavelength). At 100 Hz, the wavelength is about 11 feet and at 500 Hz it is still about 2 feet. Your cabinet is not that large. This is a basic problem with this strategy when appplied to woofer cabinets. Now there may be other reasons to add material, but that is another issue.
The higher frequencies will still be attenuated and overall re-radiation will be reduced. The response may end up slightly smoother as well.