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Diffusion vs. Sound Absorption views

I have Spatial Audio M4 Triode Master open baffle speaker in my listening room.  I have sound treatment behind the top of the speakers with sound absorption panels hung on the wall and an Aurelex foam panel down to the floor. 

It was recently brought to my attention that sound diffusion panels behind the speakers might yield an improvement in SQ over the sound absorption panels.  The advice I got is that OB speakers benefit more from rear wall sound treatment with diffusion rather than absorption.  I put the issue to you learned folks for advice.  Thanks. 
whitestix
bdp24's avatar
bdp24
9,412 posts
 

Diffusors behind dipole/planar loudspeakers are preferred to absorbers by many, though not all, owners of such speakers, for a couple of reasons. Too much absorption can result in a room overly "dead", but that’s true no matter what the speaker design. But since dipoles put out as much sound from the rear as from the front, diffusors behind them creates more depth (detractors claim it is false depth added to recordings containing no such depth), and a "bigger" sound, which is one thing planar lovers like about them.

@auxinput makes a good point about the distance required for diffusors. Not only between the absorber and the speaker, but between it and the listener. A couple feet to the speaker and 6’ to the listener, minimum, is a good rule-of-thumb. Do call GIK, they will provide you with excellent advice. I’ll soon be installing a set of their Gridfusers on the wall behind my planars.

mrmb's avatar
mrmb
299 posts
 
I have found GIK as recommended above, to be a good reasonably priced source for acoustic panels.  I installed them in our previous house and plan on using them in our new one.

If the application allows, I prefer the aspect of free-standing/movable panels not only for initial trial placement purposes, but also for present and future flexibility.  In fact, GIK just sent a flyer out last week mentioning their new "Panel Foot Kit" that will turn almost any of their products into floor standing/movable ones: http://https//www.gikacoustics.com/product/panel-foot-kit/
ptss
1,959 posts
 
On a basic level - high frequencies add sparkle and life to music even to those listeners with diminished high frequency hearing. With that in mind I suggest diffusion should be your first priority and when you feel you’ve done a decent job of it then limited absorption behind the speakers as you find provide enhanced detail and depth to your sound. What types of music do you listen to most?
whitestix OP
684 posts
 
I am keen to check out this diffusion aspect of sound treatments, as I have a remarkably dampened room (two layers of 5/8" sheetrock with Green Glue in between and several sound panels behind the speakers, and thick carpet in the room.)   I have a long narrow room (13x26x9) with the speakers on the long wall, about 3' from the wall, and I sit about 10' away on a sofa against the rear wall.  Not an ideal setup for sure, but I am working around the edges with what I have.  
If diffusion enhances the spatiality of the sound, then I am interested to explore this aspect of my system.

I listen to about 98% jazz, of the straight-ahead variety.  Miles, Coltrane, MJQ, Brubeck, Desmond and most significantly Stan Getz. 
firstnot's avatar
firstnot
248 posts
 
Since you have Spatials, why not contact Clayton Shaw, owner,
and ask the source. He is a person very willing to share. Overall
I understand absorption be best used to stop early reflections,
ie in front of speakers on side walls and ceiling. Diffusion best on front and back walls.
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