inexpensive room treatment options

Emily: I have a wall of books behind the speakers (out of necessity). This may not fit into your decor, but it sure sounds good. The shelves are not enclosed (as to not create a bunch of right angle corners) but are of the "standard" type (the little tracks that are affixed to the wall with movable shelf supports). The hardware is painted the color of the wall (White) and the shelves themselves are just White-washed pine and are very narrow so that just the books are mostly visible (wall O' books), not the shelves themselves. I have also tried hanging a large painting on canvas (much easier than the book thing) with good results. We now have a large painting on Masonite hanging from the shelves (ran out of wall space) which does not sound good (too reflective) and needs to be covered by a cloth when listening, so canvas is the way to go. There was talk in another thread of placing a thin sheet of sound absorbing material behind paintings, which is an interesting concept as there is usually 3/4" of space between the wall and the canvas.

Both of Dekay's ideas are good. The space behind the listening area is usually best suited to difusers rather than absorbers, but it depends on how close the listen position is relative to the rear wall. If it's too close, then you might be better off with an absober. That said, the drapes (heavy ones) will work reasonably well as an abosber. Another possibility is to use eggcrate foam (or other absober as Dekay suggests) and cover it by building a frame and stretching whatever fabric (preferably natural and loose woven) over it. As to a diffuser, the books will work very well. If you can't do a book shelf you can also build a diffuser panel, but it's a little more difficult. One way is to use actual egg crates (cardboard type) and coat them with a sealant of some sort (shelac would probably work well). Then you can build a frame and cover it with a suitable fabric (loosely woven, but could be synthetic as long as it is reasonable sound transparent).

You have to be REAL careful when doing ANY type of absorption. Due to most "absorbers" not absorbing the entire frequency range in a linear fashion, they can actually do more harm than good.

Egg crates, egg crate foam, drapes, etc... will all skew the tonal balance due to the fact that they will do little to nothing for low frequencies while playing BIG games with mids and treble. As such, this can be beneficial for an overtly "hot" or "bright" system but can now swing the tonal balance too far towards the "warmth" side. This is not only true for "homebrew" designs, but also of "commercial" designs.

For more info on absorption rates and how it can affect tonal balance, take a look at some of the frequency response charts that Audio Advisor has for some of the Pro-foam and ASC stuff.

For well thought out and tested "homebrew" absorbers and bass traps, try looking at Jon Risch's site. He is both an EE and works with acoustics on a daily basis. Sean
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http://members.nbci.com/Jon_Risch/index.htm

Depending on your workshop capabilities, I'd recommend my very own DIY imitations of RPG diffusors. Please email for my instructions for making them if you could consider this: you'd need a table saw or some other good way of cutting Styrofoam cleanly and neatly, and a work table, and THAT'S ALL! I have 23 square feet of RPG-style diffusors on my front wall, three of them added one at a time, and each one made a major improvement in the sound. My electrostatics have a strong back wave, maybe you don't have that, but the middle of the rear wall is an important surface to treat, and absorption isn't the best way to go.

I agree with both Sean and Tom in regard to using diffusers on the back wall and withdraw the canvas painting suggestion (unless that is all that you can do). The paintings do however work at the first reflection points on the side walls and offer superior sound (to bare walls) in my setup. When I went back in time (in my mind) I recalled that the addition of either painting on the front wall degraded the sound somewhat (even with a cloth cover). The reason that the painting is where it is right now is because it is the only place that we could find space to hang it. I hope that this is not taken to be sacrilegious, but I enjoy the painting as much as I do the Hi-fi setup.