SSB4 reflex project: massive amount of rear wall absorbent!!!

[mondogenerator]

hello.

My latest speaker project is just starting to progress. i have allowed sufficient extra volume in the enclosure to enable me to use a composite of different density absorbents on the rear wall in particular.

I am using heavy carpet/underlay, PU foam, BAF wadding, cotton wool, thick felt; and the absorbent layer will be up to 8" thick. The absorbents will grade from least to most dense as they near the rear wall. ideally i would like a reflection dead box, in so far as it is possible, without the hassle of curving walls etc.

Am i right in assuming that the longest wavelength an absorbent will absorb is a 1/4 wavelength of the absorbent thickness, assuming uniform density of absorbent? would my gradient density idea be any better than this ???

if so it should be effective to about 500Hz about.

as it is a reflex design im reluctant to stuff the entire box , hence this idea.

anyone have any input? info? criticism? personal experience?

[rcw]

You might find this article I wrote regarding stuffing reflex boxes interesting.

Volume filling a reflex box

The problem I can see with the graded density scheme is that some of the materials you mentioned will take up volume, and exactly how much I am not certain.
rcw.

[mondogenerator]

Originally Posted by rcw

some of the materials you mentioned will take up volume, and exactly how much I am not certain.
rcw.

Ah ha well i know that despite the fact i failed mentioning it.

silly me...

the box is 200% required volume, and i was planning on compressing the baf a little more than is usual,so that the volume seen by the drivers is optimum. ive read a little about stuffing reflex boxes but still not altogethr convionced its a good thing...