Enough Room? Page 5

My auditioning of the new room treatment is still in its early stages, but it does appear to be an improvement over the old. The room sounds livelier, but without harshness. Loudspeakers tried so far seem to have "lighter" sounds than before, yet are still recognizably the same loudspeakers. The room seems less warm than previously, with more clarity through the midbass region. This is most likely due to substituting a large area of reflection and diffraction for a large area of absorption (that rear wall). The result is a change in the overall room balance. Fewer of the highs are absorbed, making the mid- and upper bass seem less prominent than before. It took me a brief period to become accustomed to the slightly brighter resulting sound, but the less prominent mid- and upper-bass warmth appear to be a worthwhile tradeoff. All of these are preliminary observations based on just three pairs of loudspeakers, one of them not heard in the "old" room. But the result to this point seems to be a net improvement (footnote 9).

As to the quality of the room's soundstaging capability, it was excellent before and remains so. One addition to the current treatment recommended by RPG is placement of a Diffusor or Abffusor between and slightly behind the loudspeakers. Extra panels are on hand to try this; it is the next planned step in the ongoing saga of experimentation with the listening room.

Back at your place
You can improve the performance of your listening room. This article in no way claims to be exhaustive, and if you really want to address the subject in detail, you'll have to do some homework on your own. There are several places you can go to get information about room acoustics.

Start with your local library. Investigate not only books, but articles in back issues of this and other magazines. Good audio dealers are also becoming aware of the importance of this subject, though naturally they'll hope to sell you one of the aforementioned specialized room-treatment products.

If you have a computer, you might wish to investigate two programs designed to help you choose the best room locations for your loudspeakers. The Listening Room was reviewed in these pages in Vol.13 No.12. Another pair of programs, CARA (Computer Assisted Room Analyzer) and LEO (Listening Environment Optimizer), are furnished by Snell Acoustics to their dealers to assist in setting up Snell customers' loudspeakers. Even if you don't own Snells, many Snell dealers can provide you with a printout for your room either gratis or for a nominal fee. Or, if you have a computer, have access to one, or know someone who does, the programs themselves are available from Snell Acoustics. They are inexpensive.

There are at least two books which you might want to investigate. Though oriented to the design of recording studios, both contain enough useful acoustical information to deserve a place on the bookshelf of any audiophile who wants to know more about acoustics and rooms without delving too deeply into math-laden textbooks. Both books are by F. Alton Everest and published by Tab Books: Acoustic Techniques for Home and Studio (out of print as of January 1991, but still available in some bookstores---a good source would be OPAMP Technical Books in Los Angeles, (213) 464-4322), and The Master Handbook of Acoustics. There is considerable overlap between them, yet both have particular strengths. Each has a thorough discussion of low-frequency room modes. Acoustic Techniques (reviewed by RH in Vol.13 No.2) seems the more heavily slanted toward studio construction, but contains some useful discussion concerning the small listening room.

Master Handbook would be my choice for the audiophile wanting to know more about acoustics and improving a listening room but reluctant to purchase both books. It has the most up-to-date and thorough discussion of room-treatment materials, from carpet to foam to Tube Traps to diffusors. In fact, it devotes an entire chapter to this last, giving enough information to enable the resourceful audiophile to consider a do-it-yourself effort---though it's likely to be more than a weekend project. But Acoustic Techniques has the more thorough discussion of room isolation techniques, a matter of real concern to those able to build a dedicated listening room that can be used without disturbing the rest of the family (footnote 10). Curiously, however, only the Master Handbook covers techniques for suppressing noise from heating and air-conditioning systems---another subject you won't want to ignore if you're building a listening room from scratch. You might, in addition, want to investigate Handbook for Sound Engineers, The New Audio Cyclopedia, edited by Glen Ballou, from Howard W. Sams & Co. (reviewed in Vol.11 No.2), though this book is considerably more expensive than the above (and covers many other audio subjects in addition to acoustics).

The bottom line to all such assistance, including that attempted in this article, is to avoid being a slave to it. Acoustics, especially as applied to small spaces (ie, home listening rooms), is still very much an art. Experiment---along with liberal use of your own two ears and the gray matter between them. And when all is said and done, the furniture and loudspeakers in their chosen positions and, if you really went off the deep end, the sawdust swept up and the last of the carpenters' empty Coke cans, cigarette butts, and discarded candy wrappers cleaned up, how can you be certain that you've made the absolute best choices of listening-room layout and treatment for you and your circumstances? You can't, and you never will. This is real life. If you've made choices which significantly improve your enjoyment over what you had before---choices which provide you with genuine musical pleasure, all at a price you feel comfortable with---then you've done your job. Sit back and enjoy.

Footnote 9: For information on RPG products, contact RPG Diffusor Systems, Inc., 12003 Wimbleton Street, Largo, MD 20772. Tel: (301) 249-5647. Fax: (301) 249-3912.

Footnote 10: The techniques used to provide proper absorption characteristics within a listening room are almost totally worthless in providing isolation between rooms. There is a tremendous amount of confusion among both the public and many supposed experts on this point. If this matter is of concern, I can recommend not only Everest's books, but also his article "Muffling the Neighbors" in the November 1990 Audio (pp.69-78, with a useful appendix).