Curious, I've been looking into horn bass bins & notice almost all do not use any form of sound absorbtion material including the back chambers. Why is this so, thought that absorbtion of the rear waves is always a plus thing to do.
True. With standing waves it isn't so much about absorption it's more a matter of preventing them in the first place. Placing baffles in the right places can break up standing waves. Boxes with curved side walls help with that as well.
Thanks for your thoughts. What Im curious about is without any stuffing would it not cause coloration ? Example a BLH cabinet, I don't believe that I seen any that even recommends any thin felt to be line of the side walls or on the folds. Surely without there will be some form of coloration right, it's like talking in a room with zero furnishing, so echoey & coloured.
Agreed but I there would be some form of coloration if left undamped no ?
When we look into FLH enclosures it's more pronounce, say a La Scala bass bin, the dog house is a sealed chamber with zero absorbtion, woud this not cause lots of peaks & deeps ?
I use Peavey FH1 loaded with K33 woofers (probably Eminence Kappa 15C in a near future).
I experimented with stuffing the back chamber; first I used bitumen sheets on all internal panels covered with egg crate foam (quality one from Germany, not the cheap stuff you see everywhere); comparing with the untreated horn, the treated horn had seemingly no output, like the woofer was struggling.
I then removed most of the foam, leaving just all the bitumen sheets and ONE horizontal panel covered with foam (top and bottom panels being parallel, they are the only place where standing waves can occur). This gave the perfect balance in my system and removed some woody resonances, leaving the bass and mid bass purer and smoother, however, I feel there might be a slight diminishing of mid bass "punch"; not sure about the latter as I'm using a very low power amp for the range up to 400Hz and my room acoustics are problematic to start with.
I'm globally very happy with this mod; I sit rather close to the horns and I couldn't stand hearing the resonances and spurious vibrations in the music; in a huge room, sitting far from the horns, this mod might be counter-productive (or not).
So a little bit of damping is good, but DO NOT OVERDO IT, you would be sorry!