plaster, acrylic, concrete casts of diffusors

I cant believe I cant find any discussion about this on the internet. I've purchased a box of the auralex metrofussors. They work pretty well, near as I can tell. But instead of buying a new set I was thinking of casting copies of in concrete or plaster or acrylic. Or perhaps buying the fancy spacearray and doing the same. Has anyone ever tired this? Ethical issues aside which material do you guys think would be the best acoustically?

Yeah thats a good idea. To be honest I couldnt hear a huge difference but I attributed that to there not being enough or perhaps needing the more expensive versions. I havent read anywhere where its said that diffusion is impractical in small studio settings though.

ORIGINAL: yep
It's not so much that it's impractical, and there's certainly nothing wrong with it.

It's just that in small spaces, diffusion doesn't really help with the biggest and most common problems, which tend to come from things like room modes and standing waves, and those require big, deep absorption to deal with. The primary value of acoustical diffusion is to break up flat "echoes" from nearby walls into diffuse "reverb," and to do that in a broad, full-spectrum way requires some fairly deep irregularities in the surface. 1 or 2-inch grooves or bumps of any shape simply don't change the acoustics all that much, except in fairly specialized circumstances.

Cheers.

I've never disagreed with Yep before... but I have to say we noted a subtle yet dramatic improvement in the sound of drum kits in our performance room after installing our own version of the Auralex Space Arrays on our ceiling. There was enough of a difference that we decided to install more, once Spring hits and we can work in the garage again.

The difference was quite notable, yet subtl. I'll see if I can find a place to put up samples and let everyone here take a shot at listening to them.

I will say this... if the labor hadn't been free, I'm not sure it would have been worth it, and there's NO way I'd invest in the Auralex version.

Corey

Big difference between using diffusion in a recording space and a monitoring space!!!

I would expect diffusion to provide an audible difference in almost any recording space. Actually, let me qualify that<G>... if the space is big enough to put a drum kit it's probably big enough that you'll hear the effect of the diffusion. I'm not saying that the effect will be flattering<G>, but it will be audible! And let's face it, most of us are quite adept at finding a good spot for the microphone in less than ideal spaces<G>!

I really like the idea of a diffusor above the drum kit btw... I've used absorption before, and it certainly extends the "audible" ceiling, but now I'm going to have to try diffusion too!

In a monitoring space we have a very different set of rules and a very different set of goals.

When diffusion is applied to the rear wall of a monitoring space one is usually trying to build a LEDE(tm) room. These rooms are characterized by the arrival times of the early reflections, and the lack of specific reflections from the back of the room, so that acoustically the rear wall sort of disappears.

In order for this to work you need something on the order of 11 feet from the rear of your head (while seated at the mix position) and the rear wall. Anything less than that and the delays don't work out and the diffuse field never really develops.

A couple of designers have experimented with very complex diffusors designed specifically for really small spaces. I have not heard the results, but the literature suggests that they still suffer somewhat from the lack of time from the rear wall back to the ears.