Best thin damping material?

bcodemz

Member
2014-02-21 1:19 am
I believe the consensus is that wool felt is the best material for absorbing rear waves inside a speaker.

What if the thickness comes into play? If I'm limited to a specific thickness, say 1/4'', would wool felt still be the best material? If not, which material would be?
 
Typically with a reflex enclosure one uses limited damping (ie the ½" cotton felt) so that the damping does not interfere with the reflex action (or increase the apparent volume).

In a sealed box you need to fill the entire speaker volume to get an apparent increase in volume (nominally one can get up to about 20%).

dave
 

bcodemz

Member
2014-02-21 1:19 am
So stuffing does not take away apparent enclosure volume right?

I'm making a very small speaker with maybe 2.5L of effective internal volume, so every bit of enclosure volume matters.

If it doesn't, I can line the walls with felt, and the stuff with polyfill or something. I'm reading it is not good to overstuff the enclosure, so I'm not quite sure what the balance should be without some trial and error.
 

AllenB

Moderator
Paid Member
2008-10-18 11:31 am
So stuffing does not take away apparent enclosure volume right?
Not in small quantities. You need a fair amount to make it appear larger and even more makes it smaller again.

Higher air coupled box modes are not difficult to absorb with moderate damping. If you are going to use limited material it can be better to space it away from the walls. Waves build pressure at the walls and the opposite (velocity ie movement) is needed for this kind of damping to work.