Diffusion + flutter echo

[Dan Merrill]

this is a pretty cool link of a sound company experimenting with using 1/2 round sonar tubes for diffusion and to tame flutter echo problems. Some before and after sound bytes of their tests. Interesting stuff.

May be useful for some of you newbies who are not quite sure what flutter echo is, and also give some new ideas to others for building DIY diffusors.

http://www.allchurchsound.com/ACS/R&D/nov42001tests/index.html

 

[Michael Jones]

Pretty cool link Dan.
You know, we talk about this stuff all the time, run our calcs, and discuss ways to tame problem frequencies, but to actually see and hear the differences is invaluable.

 

[John Sayers]

I have a problem with this - if you listen to the tracks what changes is the reverb time. Diffusion doesn't change reverb time - just alters the reverb density.

I suspect that the tubes are acting as absorbers - they are made of porous cardboard which IMO would have an absorption curve similar to say 1/2" fibreglass. As far as diffusers are concerned I suspect they wouldn't have much effect under 1khz as anything lower would go straight through them.

When placed throughout the room as they have done I suspect that the sonor tubes reduce the RT thus cleaning up the room. A similar surface area of 703 would have been better.

cheers
John

 

[Dan Merrill]

John, you may be right about that. And while I will agree that I hear a slight shortening of the reverbs, I mainly appreciate the reduction of the flutter echoes, Putting that much 703 on the walls may have a similar effect of taming the echoes, but from experience I've found it can also taint a lot of the desirable ambience of a live room.

Of course, this is not necessarily what we strive for in our control rooms...

 

[John Sayers]

You'd probably only need half the surface area of the sonar tubes to achieve a similar result using 703. I'd like to see them test that anyway

cheers
John