Loudspeaker Placement

Loudspeaker placement is often as important as the choice of loudspeaker itself in determining the overall sound quality of a system. There are a couple of principles to get you started, and if you’ve done your homework on the room, above, placement of the monitors is going to be a lot more benign, not to mention easier.

To begin with, the loudspeakers need to use the same median plane as the room has – this is a key ingredient for symmetry.

Secondly, the tweeters need to be at ear height, and/or directly aimed at the ears (unless the manufacturer specifically tells you otherwise).

Third, the speakers need to be either mounted “in” the front wall (“soffited”) or be far enough “from” the front wall to keep low frequency response from being seriously disrupted by interfering reflections from the front wall. Mounting “in” the wall is a pretty nice thing to do, and it is moderately easy if you build something like my absorbent “monitoring shell” for the front wall that includes cutouts for the speakers.

If you want the speakers to be out in the room, it is good to get them several feet (at least 3 feet, 5 is better) from the front wall, unless that wall is REALLY absorbent at low frequencies. Similarly, you should avoid placing the speakers too close to the side walls (I’d suggest 3 feet as a minimum distance). Finally, you should avoid having the speakers at the same distance from the front and side walls, if possible.

For the rest of it, there is a common practice tradition of listening to speakers that are each 30° off the median plane (and we do our serious listening ON the median plane), so that the two loudspeakers and our listening position constitute an equilateral triangle. This setup works pretty well, but the 30° part is fairly informal and so long as the phantom images and spaciousness are working well, you can have wider or narrower spreads without much problem. What you definitely should have is symmetry, and you must be listening on the median plane.

Loudspeaker Behavior

Ah, yes. The loudspeakers. They are part of the system, aren‘t they? What do we need from the loudspeakers themselves? I’ve been working hard on this question over the past couple of years, and have some suggestions, as you can probably imagine.

First off, loudspeakers need to have reasonably flat frequency response on axis. They also need to have pretty benign off-axis response, which is to say that even though the high frequency output will fall off dramatically off-axis (except on MY loudspeakers, of course), it needs to do so smoothly. It would also be nice if it doesn’t fall off too much over +/- 15° at, say, 10 kHz.

Low distortion is another issue for loudspeakers. Transducers, which are mechanical devices, generally have a pretty narrow range of linear behavior. Keeping speakers with small woofers out of significant distortion is hard.

The point here is that you need to pick your speakers with care. “Any old speaker” is no longer good enough, particularly once you’ve gone to the trouble to get everything else right. Without a doubt, you will also need something crass like Auratones to check your mixes on, but you really do need something better, something really good, with which to do your tracking, mixing and maybe a little pre-mastering. The loudspeaker is your musical instrument. It is also a lab instrument. Yikes! Enough said!!

Where The Rubber Hits The Road

As you can see from the above, it is all actually pretty straightforward stuff, although you can get into some serious carpentry projects if you are so inclined. In short, you’ve gotta get your room quiet, make it symmetrical, get the decay time down, buy good loudspeakers and place ‘em carefully.

If you do those good things, and are careful and fussy about maintaining ‘em, you can actually have really nice sound in your control room for pretty cheap. The trick comes, of course, in adapting your particular space to this set of requirements. You will have to make all sorts of compromises. That’s part of the game. The trick is to make compromises that get you close to where you want to be. Time-sharing the AC for lower noise floor, re-arranging the furniture for symmetry, sealing up a window for isolation and symmetry, fiberglass or foam on the front wall to knock down early reflections and shorten decay, moving the speakers around to different positions for symmetry and bass response.

Make a dual check list showing these principles in one column and how your room stacks up in the other. From this derive a list of the things you can do to get your room closer to these principles. Estimate the cost of each thing. Do the cheap ones first! Do one at a time and evaluate the improvement you’ve gotten. Nibble away at it. Keep in mind, it’ll never be perfect, but that doesn’t matter – nothing ever is! The trick is to get the most performance for the least bucks.

Happy nails!

Below are some rude and crude drawings of a prototypical monitor shell in a small room, FYI.

Dave Moulton is trying to build the perfect loudspeaker. You can complain to him about anything at davemoulton.com.

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