The Audio File: Speaker Sense

The Audio File: Speaker Sense

For the past several months, I've been working on a new loudspeaker design - actually several designs using the same driver complement, sort of a "theme and variations" concept. The rationale underlying this approach is based upon the simple truth that loudspeakers perform differently depending on where they are placed in a room. Most of us share our listening space with others, and often that space is a multi-function room, subject to a variety of factors constraining where we can "set up the stereo." Hence, a basic understanding of the interaction between the loudspeaker and listening room will better equip us with the resources to fine-tune our system set-up in order to achieve a more enjoyable, believable musical presentation.

It is well beyond the scope of this column to delve into the complexities of room resonant modes, acoustic treatments, etc.... Rather, I'll try to offer a few simple guidelines and suggestions for you to try when setting up you own stereo system. Some of the following topics may seem self-evident, but I've been surprised to find that many listeners have never been educated regarding even the most basic fundamentals of good domestic music system design.

First, if you're shopping for new loudspeakers, give some advance thought to where you want to place them in the room, and make sure that you discuss this matter with your hi-fi salesperson. Specifically, will the speakers be located on a shelf or stands directly against the wall behind them, or can you place them a few feet out into the room? Do you have an unusual room geometry that requires you to place the speakers well away from room boundaries (over 4 feet)? How far apart will the speakers be from each other, and how far from the side walls? How is the room furnished in terms of wall and floor treatments, windows, doors, furniture, and ceiling geometry? A good salesperson will be able to steer you towards loudspeakers that work particularly well in certain types of rooms, or in general positions within a room, and recommend against other speakers that might potentially offer a very high level of performance, but that will not work well at all in your specific room. For example, some speakers are designed to be used right up against a wall, while others will only deliver their particular blend of sonic magic with six feet of empty space behind them.

In general, arrange your room so that you can place the loudspeakers between 6 and 10 feet apart, leaving 2 to 3 feet of space between the backs of the speakers and the wall behind them. The vast majority of well-designed speakers can deliver exceptional results within this placement range, though performance will still vary greatly from room to room. Ideally, the optimum listening position - the "sweet spot" in audiophile parlance - should be on the center line between the two speakers, somewhat further away from the speakers than they are from each other, perhaps 10 to 12 feet, if the speaker are 8 feet apart. In very large rooms, you can increase these absolute distances, but try to maintain the relative proportions. Obviously, read the manual for your particular speakers first; the manufacturer may offer detailed placement recommendations based on particular design decisions.

When your system is optimally aligned within your room, you should hear a coherent sound field extending between (and sometimes beyond) the two loudspeakers. With well-recorded music, you should be able to visualize the placement of instruments placed within that sound field. Stereo is very much an "emergent phenomenon," wherein a continuous whole is generated from two discrete sound sources, the left and right speakers. For this reason, err on the side of placing the speakers too close together: when a stereo pair of speakers is placed too far apart, you'll hear each speaker as an individual source of sound, rather than the intended broad panorama stretching from speaker to speaker.

No matter how good your equipment, its performance can be severely constrained by the harsh, muddying, fatiguing sonic signature of an overly, "live," reverberant listening space. Good listening rooms typically have a natural balance of real-world furniture, wall hangings, and carpet. Avoid extremes, such as overly reflective, hardwood-floored rooms devoid of furniture, or "dead" parlors packed with over-stuffed couches and plush chairs. I've grown quite convinced of the merits of placing loudspeakers on the longest wall of a room, aiming across the shorter dimension to the main listening position. This orientation increases the distance from the speakers to the side walls, thereby reducing the impact of interference from side wall reflections on the pure direct sound from the speakers.

Finally, be creative. Unusual spaces may respond best to unusual solutions. I've been able to compensate for particularly nasty room resonances by placing a pair of loudspeakers across the room's corner, with the added benefit of allowing the corner to be filled by a large video monitor. Large bookcases filled with CDs, books, records, and tapes do a wonderful job of dispersing sound within a room. Experiment, listen, rest, and refine. The science of acoustics as it pertains to real-world, domestic listening rooms is both inexact and multivariate. With attentive ears and a little attention to detail, you'll be on your way to getting more out of your existing music system than you might have imagined possible.