[Adamay]

Hi Danny.  I've got BH5 in a pair of Paradox 3's from you; a couple of nights ago I was fooling around and added a small bit of fiberglas insulation, very loose, to the bottom (inside) of the cabinet.  The effect was eye-opening: clearer, better defined bass from the lower mids on down, and more powerful, impactful bass. (I might have lost just a bit of extension at the very bottom, though -- still checking on this.) Obviously, adding the stuffing must have helped break up internal standing waves.  This experiment got me to thinking.  Would the speakers benefit (maybe even dramatically) from removal of the white surface "skin" from all of that Blackhole 5?  Or, I could remove only strips of the "skin," thus alternating between the skin and open-cell foam.  (The inner walls are virtually covered with the BH5.) I assume the skin on all of the surfaces actually helps to perpetuate standing waves rather than breaking them up, and also serves to reduce the inner volume of the cabinet by quite a bit.  With the skin removed, the open-cell foam might absorb/break up those standing waves, and also yield a greater inner volume.   Am I totally off-base?  I'd be grateful for any advice/corrections.  Thanks.

[Danny Richie]

The skin has a minimal effect. Sound waves will pass right through it. Adding or removing it won't change how the woofer pressurizes the box. It doesn't effect the box volume. You did increase the box volume with the added insolation though, and it helped to absorb more standing waves. I typically use a handful of insolation right behind the woofer wether using BH-5 or No Rez.

Experimenting with pealing a little of it off won't hurt though (if you can get it off). Feel free to play with it and let us know what you think.

I opted not to have a surface layer added to the No Rez.

[Adamay]

Thanks!

[Christof]

You did increase the box volume with the added insolation though, and it helped to absorb more standing waves.

Danny,

Could you explain this a little more.  Insulation "tricks" the driver into thinking the box is bigger but what does NoRez or BH5 do in terms of the driver/box volume relationship.  Would the application of NoRez make the internal volume smaller yet trick the driver into thinking the volume is larger so it all ends up a wash anyway but you benefit from the sonic dampening of the material vs a solid wall?  Forgive my anthropomorphism of loud speaker drivers

[Danny Richie]

Could you explain this a little more.  Insulation "tricks" the driver into thinking the box is bigger

You are just slowing down the air flow in the box just as if the box were larger.

what does NoRez or BH5 do in terms of the driver/box volume relationship.

The open cell foam layers posses a little resistance (or delay) as the box pressurizes and de-pressurizes just like adding more poly fill of fiberglass. The damping and barrier layers do take up some air space but it is closer to being a wash than having any real effect on box volume. If anything the No Rez adds just a little.

The damping and deadening of the enclosure wall is the real benefit.

[laserman]

My P3's have a thin layer of fiberglass laying over the top of the BH 5 on the bottom and the rear.  Danny made mine and placed the BH5 in the speakers before he shipped them, so they are rectangle pieces with some space between them.  When I first got them I tried all sorts of modifications and realized the biggest improvement I could make was to my room.  I treated it and it really improved on the entire frequency range.  I'm glad your's worked for you.