Installing Acoustic Panels: How much is too much?
At times the subject of room acoustics seems a bit like the Defense Against the Dark Arts class in the Harry Potter novels: very important, but always arcane. And the teacher never lives to tell about it.
Since I'm mid-way through the first semester of acoustics work on one of my music and film rooms, I'd thought I'd provide some observations before my character is disposed of.
My first point would be that room acoustics are simply huge in the quality of music reproduction. It is unfortunate that the necessary products are visually obtrusive, and therefore best suited to dedicated music and film rooms, or I think more people would avail themselves of this technology.
My second observation is that treating side and rear wall reflections not only has a great impact on transparency, but it also has a big effect on spectral balance (how bright or dull a room sounds).
Many acousticians, especially those employed to do studio work (the main source of employment for such folks), will encourage the placement of absorptive/diffusive panels on most side and front wall surfaces in a room. This has two advantages: it kills early reflections thereby increasing the ratio of direct to reflected sound for better articulation, and it places panels on the wall whose reflective characteristics are smoothly controlled over the frequency spectrum.
While many audiophiles, whose primary experience is with absorption on the walls, will look at a fully treated room and think it must sound "too dead" in fact the use of panels that absorb, reflect and diffuse makes it unclear how much panel treatment is too much. And some acousticians have said "any early reflection is a bad reflection".
To start some experimentation, I installed 48 RPG B.A.D. panels on the front and side walls of my room. These panels covered about 80 percent of the wall surface, leaving only strips near the floor and ceiling exposed. In this configuration, my system is vastly more articulate that when the room was untreated. But it did sound a little dead -- slightly polite, and lacking air at high frequencies. I used this configuration for several months and listened to hundreds of CDs, before coming to this conclusion.
My next step was to remove one-third of the panels, so that I now have 32 panels up. That means about 50 percent of the side and front wall surface is treated, although I left more treatment at the early reflection areas and removed treatment mostly near the ceiling and floor. This setup is much more lifelike, although it might have gone slightly too far in the reflective direction.
My tentative conclusion: You can usefully install far more treatment than most audiophiles would intuitively suggest, but the full studio treatment is too much.