[Inscrutable]

I am thinking of ways to easily deal with diffusion/diffraction on the live end of a LEDE room.  Some suggest curved plywood panels, which more diffract than diffuse.  I was thinking of DIY a vertical slot style diffuser.  I can't lay my fingers on it now, but found a fairly incomprehensible calculator.  I was thinking about doing this on the full height and width of my rear wall by either ripping and placing 2x lumber side by side, or routing top and bottom plates and using 1x lumber for dividers. Any suggestions for a calculator for laying out the widths and depths of the recesses, or advice to steer me away from a stupid idea?

[ctviggen]

Here's one:

http://www.mhsoft.nl/Diffusor.asp

If you can buy/borrow/check out the Master Handbook of Acoustics, F. Alton Everest, he gives a variety of diffusion formulas.  It's also helpful to know the names of these things (like "Quadratic Residue Diffusor", "Shroeder Diffusor", "Primitive-Root Diffusors") so that you can search online for them. Supposedly Quadratic are better than Primitive-Root diffusors.

[bpape]

In a LEDE room, I'd do the polycylindrical type (it wiill also help in the bottom end where QRD and Skyline types won't as much)

Unless you're going to build a compound slot type diffusor, the size required to do the wall will make it all but useless at higher frequencies.  If you make them smaller and use many of them, you can run into issues with cancellations from the various instances of them interacting with each other but only at some frequencies.

The Skyline (2D) tend to be more forgiving about being mounted in groups as long as they're rotated properly in relation to each other but are a lot harder to build and pretty large to get down into the hundreds of Hz range - much less the bass.

[ctviggen]

Oh yeah, I forgot about those!  The Master Handbook discusses how those can be made.  They would be much easier to make than the quadratic style, but I don't think the specular performance would be as good.  On the other hand, as bpape says, the low frequency performance would be much better.

[bpape]

Actually, if you look at the plots for the QRD's, they're pretty spiky.  The Polys actually will distribute it more evenly though not as randomly.  They also tend to require a bit more space between you and the diffusor before they become as effective.

[Inscrutable]

Bob,
That's exactly the one (there are a couple more pages as well) to which I referred.  And I do have the Master handbook ... but of course it's packed in storage with the rest of my life right now (moving ... long story) and I hate to rebuy it.

As soon as I do some more reading and homework, maybe i can ask an intellignet question ... perhaps a reach, i know.

[Glenn K]

In a LEDE room, I'd do the polycylindrical type (it wiill also help in the bottom end where QRD and Skyline types won't as much)

Unless you're going to build a compound slot type diffusor, the size required to do the wall will make it all but useless at higher frequencies.  If you make them smaller and use many of them, you can run into issues with cancellations from the various instances of them interacting with each other but only at some frequencies.

The Skyline (2D) tend to be more forgiving about ...

Bryan where in the Master Hand book is polycylindrical?? I see Moncylinder and bicylinder by not polycylindrical..  i just want to better understand them..

Glenn

[bpape]

I don't remember which section but it's in there somewhere.  You can also look at all the old BBC research for explainations - though specifics are pretty hard to come by.

Bryan

[Glenn K]

I don't remember which section but it's in there somewhere.  You can also look at all the old BBC research for explainations - though specifics are pretty hard to come by.

Bryan

found it!! page 209

[ctviggen]

Too bad you're not near Austin:

http://cls.audiogon.com/cgi-bin/cls.pl?accstwek&1143303207

There are actually quite a few RPG products on Audiogon, but you have to wait for them to come up.