The Stereo Soundstage

What is the angular separation of your loudspeakers as viewed from your favorite chair? Whatever your answer, it's wrong. Of course I don't mean that it's a factually incorrect answer, just that any single value of subtended angle cannot be ideal for all recordings.

Classical stereo theory, applicable to recordings made with crossed-pair coincident microphones, suggests that for optimal playback the speakers should be placed 45 degrees to the left and right of the stereo centerline, subtending a total angle of 90 degrees. But in many living rooms (and dealer showrooms as well), the total angle is only 45 degrees or so. Many books and magazine articles suggest an intermediate answer of 60 degrees (±30 degrees from the centerline), with the two speakers and the listener's chair forming an equilateral triangle.

Your preferences may depend on the recordings you play. When recordings that were made with widely spaced microphones are heard through a wide-angle (90 degrees) playback system, the resulting stereo image tends to form two separate pools around the speakers, with a "hole in the middle" (ie, center-stage sounds become phasey or ill-focused). This may account for the American preference for a relatively narrow spread of 45 degrees to 60 degrees between speakers, an angle at which spaced-mike recordings usually cohere into a reasonably stable image with some center focus. But when coincident-mike recordings are heard through speakers only 45 degrees apart, the total apparent width of the orchestra may be only half the distance between the speakers, sounding like fat mono instead of real stereo.

The obvious answer is that we should all mount our speakers on rollers or lateral tracks, so that we can move them closer together for some recordings and spread them apart for others. Of course, there might be some practical difficulties, particularly with Tiptoes and thick speaker cables. And in the "wide" setting you wouldn't want to get the speakers close to sidewalls whose reflections would color the sound and muck up the imaging. A better approach might be to leave your speakers where they are, mounting your chair on a front-to-back track so that you can move closer to the speakers for coincident-mike recordings and farther away for spaced-mike recordings.

For some of my listening, I sit back in my easy chair with my feet up. At other times I sit on the edge of the chair, leaning forward. For all I know, this more attentive posture may subconsciously alter my perceptions in some way. In any case it moves my ears 18" closer to the speakers, and it alters the sound far more dramatically than most of the tweaks I've tried (damping rings, green ink, different cables). The recorded soundstage becomes wider and deeper, ambience is more distinctly separated from instruments and voices, and a chorus becomes an assemblage of individual voices rather than a blended sonic mass. (Best of all, this improvement is free!)

This may sound like an April-Fool joke, but I'm being at least half-serious here. If you're not convinced yet, look at what Guy Lemcoe said (Vol.15 No.3, p.142) when Michael Green "tuned" Guy's listening room. The tuning consisted mainly of removing some superfluous RoomTune panels, moving the speakers 2' forward into the room, and Guy's chair forward by 2', thus reducing the total chair-to-speaker distance by about 4'. The result, according to GL: "I suddenly felt privy to the musical experience to a degree beyond any I'd experienced before. I became an intimate part of the soundstage---no longer an observer, but a participant in the experience! Minute performance details became unambiguous, lessening the interpretive burden. A result of this was that I became a more relaxed listener."

In my experience, the change caused by moving closer to the speakers is not always for the better; with some recordings I still prefer to sit back in my chair. The optimum distance clearly depends on the recording. If this weren't so, I would simply move my chair forward to the closer position. Since I'm constitutionally lazy, the ideal solution might be a knob on my preamp that would vary the subjective chair-to-speaker distance. This is not as impossible as it may seem.


Doctor Fine's picture

I have my listening chair positioned so that I can close the "hole in the middle gap" by leaning back or increase the spacing by leaning forward.