For in-ceiling speaker installations, what have you found that works best for reducing sound tranmission and improving the overall sound. I'm looking for insulation type and brand recommendations. I've used custom made speaker boxes for new construction and they work great. But my question pertains to retrofit installs. Thanks.

Bob,

If you seal the cavity inside the wall with a box small enough to fit, you will reduce the bass directed at the listener considerably.

As for adjacent room SPL reduction, there is no box manufactured by anyone that really reduces the amount of bass you hear in the room next to the room with speakers. You can typically get no more than 3dB (barely audible) of reduction from any enclosure that fits in in the wall. Remember, a 20Hz tone is 54 feet long. You would need a very thick absorber or an extremely inert enclosure material (brick or concrete) to stop the transmission of deep bass sounds.

However, you can make some dramatic reductions of the midrange and treble frequencies and "tighten up" the mid bass, by installing equal amounts of insulation behind each speaker. Be careful not to put to much, woofers need to "breath" to pump out high volume deep bass sounds. To a degree however, the more insulation you pack, the more you "increase" the apparent size of the wall cavity.

Miraflex is nice. Here is a link to the Owen's Corning website.[Link: owenscorning.com]

It doesn't make you itch. It is approved for in wall use, and it is a pretty white color.

Stephen Long did some acoustic testing for an issue of CEPro a year or two back and recommended it too.

Best Regards,

-Eric

Eric Johnson
800-247-7001
www.hometheaterpro.com



This message was edited by Eric Johnson on 05/28/02 20:09.39.

Eric,
Thanks for your help. That's just what I was looking for.