XF412 Internal Damping material

[CapnValamir]

Hi everybody, it's awesome that there's so much help available here. Apologies in advance if this has already been discussed somewhere.

I'm working on a XF412 build. The instructions instruct to line the interior with 1-1.5" thick acoustic/open-cell foam, or 1/2" felt carpet padding.
Parts-express also has a recycled denim material:
https://www.parts-express.com/Sonic-Bar ... quantity=1

Are these options all equivalent? Is there any reason aside from cost/availability to choose one over the other? Should I be planning to get several and A/B compare them?

A potentially relevant factor: I'm using Scumback drivers, which are 5.125 deep. So, I've increased the overall cabinet depth by 2" to accommodate the additional depth and potential differences in magnet diameter. For a deeper cabinet, is less or more damping material desirable?

Also, I'm building the closed-back version.

Thanks!

[Bill Fitzmaurice]

They're equivalent in how they work, but not in price. Carpet padding can be free from local carpet installers as scraps. The additional cab depth won't have any effect.

[CapnValamir]

Thanks Bill!

[RunTheOtherWay]

The point of cabinet lining in my way of thinking is that it has an effect of making the cabinet acoustically equivalent to something larger and for that to work, air needs to be able to get in and out of the material and that characteristic is more important that how dense or heavy the material is. What I did for what was a very small enclosure was to take polyfill of the sort used to stuff craft pillows, plushies, etc. and grab tufts out of it with my gloved fingers; think of having a tuft between your fingers like a sloppy bowtie, maybe not as big. Then (this is why the gloves), dab hot glue where you've pinched the tuft together in the middle, and press the glue dab against the cab surface. That might get pretty labor intensive for a bigger cab so it might work as well to use a material like this https://www.walmart.com/ip/Poly-Fil-Ult ... pe=REGULAR and just bang a staple gun all over it - but if I did that, I'd try to pick at the surface to give it more of a "pile." Again, the point is not to present the air with a dense and well-defined surface but a loose one that the air has to engage with *inside* it. It may be the case that sound trying to make its way through amorphous fibrous material actually has a lower effective velocity; if that's true then it would really be as if you had a larger cabinet.

[Bill Fitzmaurice]

Cabinet lining damps internal reflections of midrange and high frequencies that otherwise will meet the cone, causing response zits. It doesn't make the cabinet equivalent to a larger box. Stuffing a sealed cab does something similar in that it lowers the system Q, which can tame a midbass response hump that results in a boomy sound. A larger cab lowers Q, and it also lowers the box frequency for lower response. Stuffing doesn't do that.