Diffusers at Hope and in general (advice sought)

[garyrc]

Are those diffusers that I see on the ceiling in the pictures from Hope (Pilgrimage) a special Klipsch design, or someone else's product?

Does Klipsch sell them?

Does anyone know of a website with diffusers that don't cost an arm and a leg?

The best diffusion (and sound) I ever heard was in a room with a huge, very rough hewn and multidimensional, brick fireplace between the speakers. The fireplace reached the high ceiling.

To simulate (or exceed) this, I would cover the center part of the wall between my Khorns and above the Belle center channel with RPG Skylines (I've seen pics of a room like this) if they just didn't cost so damn much.

Would it hurt the diffusion much to put a purportedly acoustically transparent fabric in front of diffusers (like ACOUSTONE maximum transmissibility FR 94 fabric)?

Half kidding, but then again .....If a diffusing area can be thus covered, maybe I'll just put in a big pile of randomly oriented broken bricks and stones, as deep (i.e., varied) from front to back as the 20" deep Belle, mortar the bricks/stones, spray paint them black, and make sure no direct light source is aimed at the fabric -- if this is too diffuse, or bright, wads of absorbent material could be added. That damn fireplace sounded good!

[colterphoto1]

Hello Gary,

You'd be wanting to spend some time on the Architectural Forum then.... They talk about diffusion and absorbtion and reflection and all that stuff over there. There is a place for each but it's not as randomly selected or placed as one might think.

Look for a guy named Artto and do what he says, you'll be fine!

Michael

[DrWho]

The diffusors are discussed in the Dope From Hope and attached should be the page you might be wondering about. I'm not sure who Dr. Boner is, but his name pops up from time to time. They are very easy to build and probably one of the cheapest good treatments out there.

As far as your crazy brick idea - no, the acoustically transparent fabric will have no detrimental effect. As far as how to arrange the bricks - I remember reading a paper online somewhere about recording studio design that described a certain pattern that affected a wide range of frequencies equally.

One of the best acoustical materials is actually unpainted brick - but the second it gets painted it turns into one of the worst. The ridigd porous nature of the stone is its biggest advantage.

[WMcD]

My thought is that we really don't have data on realistic room treaments.

It is my thought that we all start with six surfaces. There is a lot of traffic about non-parallel walls and massive amounts of treatment. Such are beyond the capabilities of most of us.

On the other hand, there are data that everyday irregurlarities in otherwise flat walls have beneficial effects. E.g. bookcases, and even the casements of windows.

Ceilings are the toughest to do in a graceful way. One room in Indy had tastefully placed blocks of fiberglass about 3 inches thick. Not the Skyline pattern.

My guess is that we're overlooking some miminal schemes which achieve 80 percent of what more complicated schemes accomplish.

Gil

[pmsummer]

[DrWho]

oops, I didn't even realize my attachment didn't make it!

[PrestonTom]

Diffusion is a tricky one.

I am not sure what your background is, so forgive me if my answer seems simplistic or condescending. Treatments really need to be done in conjunction with measurement, since the treatments can be quite expensive and obtrusive.

Typically the first course of action is to minimize the first refelections. This is usually done with absorbtion and becomes more difficult if you need to absorb at the lower frequencies. After this, next would come treating the bass. Absorbtive material gets tricky and impractial (due to the sheer volume required) so trapping is usually required (choices include Helmholz resonnators, tube traps etc) and the measurement is even more critical to the design and placement.

The third round of treatment would be diffusion. The basic problem is that diffusers work best if the space is large and secondly the diffuser's size is function of the wavelegth (inverse of fequency). Traditional diffusers need to project from the wall about 1/2 the wavelength. Down to 500 Hz (2 feet) the depth would be about 1 ft. Newer designs allow diffusion down to about 1/4 wavelength. These newer versions are "highly designed" and can not be constructed in a casual manner.

The results one gets with bookcases and uneven brick are probably not giving much diffusion at very low frequencies.

So my question is: are you really interested in diffusion or would would absorption or trapping be more appropriate. In answering this, measurement should be a integral to your question/answer IMO.

Good Luck,

-Tom

[hwatkins]

So my question is: are you really interested in diffusion or would would absorption or trapping be more appropriate. In answering this, measurement should be a integral to your question/answer IMO.

Good Luck,

-Tom

From all I have read and tried - absorption and trapping are something I can have much better success with than diffusion = for all the reasons noted above. I think it requires more experience and dilligence to get noticable good resuls from diffusion tactics.

That is the same reason I generally keep my fingers out of the deep inner workings of an amplifier....

[DrWho]

I've had the opposite results actually...misplaced and too much absorbtion will sound very bad, but misplaced and too much diffusion can't really be a bad thing.

[garyrc]

Thanks for all of the responses.

Since I really can't afford many professional diffusers, I'll experiment with home made, plus redirectors, like those of Dr. Bonner. There is only one small area of the listening room / Home Theater (containing 6 chairs) that needs to be ideal, and the walls (and potential diffuser sites) are pretty far away.