R-e/p: Tell us about redoing the control room for Village.
GEORGE AUGSPURGER: From my standpoint, even before getting into the subtleties of those things that the client may like, there are a number of things you do in any control room.
One is that you try to get the thing as nearly as possible to be bilaterally symmetrical. You’re stuck with two channel and four channel stereo, which are both oriented left and right, and to get any kind of control in the center of the room you’ve got to have the left and right identical.
So the first thing to do is to make the left and the right halves of the room identical, at least acoustically, if you can manage that. And in this case, (Village studio B) that was easy. We shoved the center of the console over a foot or fourteen inches, and developed the whole room symmetrically from the mixer’s position.
Then the next thing we try to do is to work with the location of the monitor speakers and the immediate surfaces surrounding the monitor speakers. We try to get a reasonable amount of diffusion in the front part of the room, and try to make use of desirable first order reflections and try to control the undesirable ones.
The desirable ones are the ones that help localize the image where you want it and help direct the sound toward the area of the console, where the people are hearing it.
The undesirable ones are, for example, a reflection off the right wall of the room from the left hand speaker, or something like that cutters up your image. One of the biggest problems is to avoid echoes that ricochet right off the face of the console. This thing is always sitting there, it’s a big reflective surface and it’s always a problem.
R-e/p: Well, specifically what did you do for the Village’s reflections?
GEORGE AUGSPURGER: We used, in this case, two major reflecting surfaces in the ceiling area, above the speakers. We used the side walls immediately adjacent to the speakers. We knew we were going to flush-mount the speakers in the space that was already there, and those immediate surfaces were all worked out, in an attempt to get the proper characteristics.
R-e/p: Did you mean in terms of the angles and the surface material?
GEORGE AUGSPURGER: Right. Those are valuable primarily as reflecting surfaces; there’s not very much absorption on those surfaces. There’s a reflector up there which was suspended so it could be adjusted after it was hung up, in case we wanted to make slight changes. Then, once you get to that stage, you start worrying about the rear speakers.
Admittedly they are not as important as the front ones, but you try to keep their orientation and the overall sound as close as you possibly can to the front speakers. You start worrying about unwanted reflections, primarily off the rear wall, where people like to stack up racks and tape machines and things like that.
Fortunately, in this case we did not have any tall things back there. And you start worrying about the effect of the normal room resonances down in the low frequency region, because once you get into the bass region, as you well know, every moderate to small room just becomes a big resonator with its own characteristics.
What we try to do there is to control the ones that you can predict. You can never predict all of them but you try to control the ones you can predict in relation to the console location. In other words, at this point, you have to give up statistical acoustics. You can’t say, “Well, on the average, there are going to be so many modes in the room,” because the only ones you care about are the ones that are screwing you up right there at the console location.
So we try to break up the major floor-to-ceiling mode which usually is a problem. We use sloping surfaces and traps.
R-e/p: Is that the reason for the angled ceiling?
GA: Right. The angled ceiling does a double duty in that respect. The area above it becomes a bass trap and the geometry of the angle itself is designed to help to break up the floor to ceiling standing wave at the console location.
The rear wall is usually made as absorptive as possible down into the low frequency region. The corners of the room typically are good places to work on low frequencies, because all the low frequencies pile up in the corners.
And in the front, where we have angled reflecting surfaces, the areas behind those become bass absorbers.
R-e/p: How docs a bass absorber work?
GA: There are a number of ways you can approach it. There are various kinds of tuned absorbers that people have used over the years.
If the space is big enough, and if you can work it out geometrically to where the location is right, then you just stuff it full of fiber glass and let it work as a broad band absorber all the way down, (you hope) into that low frequency region.
R-e/p: I’ve heard people talk about using hard fiberglass and soft fiberglass absorbers. What is the difference?
GA: Fiberglass is available on a scale from the fluffy stuff you use for thermal insulation, which is Owens-Corning 701, to the rigid self-supporting board, the 704 and 705.
It’s simply compressed, it’s much more dense, so for a given volume or a given weight, it’s much more effective in absorbing sound than the lighter, fluffier stuff.
R-e/p: In other words, it isn’t for different frequencies necessarily.
GA: No, typically not. Fiberglass, no matter which type, is essentially a broad band absorber, depending on how much space you’ve got behind it. If you want to make it selective, then you’d do things like putting resonant panels in front of it or putting perforated Masonite in front of it.
R-e/p: I noticed the slats on the rear wall of the studio. Are they part of a tuned absorber?
GA: That is primarily visual. That area isn’t as deep as we’d really like to have it, but it’s intended to be primarily an absorber. The slats are small enough that they reflect only a few very high frequencies. It’s primarily just an open grill. The design of the thing John Edwards (Architect) worked out to be visually appealing.
R-e/p: It resembles some type of slotted helmholtz resonators I have seen, tuned to certain frequencies.
GA: No, it is just, a non-selecting broad band type of thing.
