Nearfield Placement

 

Nearfield Loudspeaker Placement

 

 GUIDELINES FOR SETTING UP SPEAKERS
(is the rule of thirds dead?)

by
Leo Massi

Sound II, North Dartmouth, Massachusetts
(reprinted with permission)

 

The following is an attempt to provide a guide for setting up speakers for those of you who may feel you need suggestions. It is intended to take some of the randomness (and insecurity) out of speaker placement. It is not intended as absolute "gospel".
The need to be sensitive to the issue of decor is an individual matter, and if that applies to you, our hope is for you to use whatever out of this that works for you.

I have compiled this system by decades of (sometimes) objective observation, the enlightened teachings of Michael Green, room treatment expert (? The next audio Messiah?), and from Joaquim Gerhardt, who has extensively published on this issue, and may be bordering on genius and regarding sound wave behavior in a room, and particular sensitivity behaviors of the human ear. Joaquim lives in Germany and is also the designer of Audio Physics speakers.

Leo

 

The following comments apply to truly phase coherent speakers, the majority of which tend to have simple (or no) crossovers. This type of speakers, if well designed, will generally display better timbral accuracy, harmonic integrity, and a natural seamlessness. It is hard to put into words just how much even the simplest crossover, or variance in driver material adds to a sense of UNREALITY. Conversely, this method may not apply to speakers with complex crossovers (i.e. some Thiels, and many others) because, as you will see later, if you sit too close to these speakers, you WILL HEAR THE CROSSOVER. Here we go:

 

STEP #l ESTABLISH PROPER BASS RESPONSE 
It is NOT absolutely true that one gets the best bass near the wall. For example, corner positioning may substantially enhance bass response below 40 to 50 hz, yet may drastically reduce mid-bass output at the listening position. Panels, or rear firing ports may elicit adverse peaks and "suck-outs". If the positioning causes standing waves or "suck-outs" you can bet the whole tonality of the presentation will be off, and trying to fix this problem by changing cables or amps is like trying to hold on to a fist full of wind. So, finding the "bass" is the first step, and hopefully, you have a choice on which wall you position the speakers. If you position them along the wider wall you will get a better (read wider) stage presentation. If they are placed along the shorter wall, it is more unlikely that you will get as wide a stage, yet, if you can thusly accommodate their placement closer to you, the listener, you will experience a vastly improved sense of depth. In any case, the presentation of stage width should always go out well beyond the two speakers.

There are three positions suggested in Figure A: good, better and best. While your room may vary, do try to apply, or at least experiment with, these rules. The listener should be probably within a couple, three, feet from the rear wall to minimize de-focusing reflections from the rear wall. It wouldn't hurt to have some sort of sound dissipating material on the wall part directly in back of the listeners head.

Somewhere within a foot to an inch of the exact middle of the room will give you the best OVERALL bass response

Front or rear quarter positions will be close seconds. These distances should be measured with a tape and, while slight deviations could be beneficial, being a foot or more off is likely to mean your bass response (and overall tonality) will 
be off.

FIGURE A
quarters room speaker placement

 

The front quarter position takes most of the back of the room out of play and will give you the most holographic sense of depth and is therefore my favorite. It is referred to as "nearfield listening", and it is a never ending surprise to me how many people have never been exposed to the effect this placement generates. Middle positioning is second in depth, and most often extremely acceptable, indeed some speakers with crossover complexity (or errors) will actually benefit from this positioning. Rear quarter placement is a most acceptable compromise where decor demands. Having taken time to ponder and execute the positioning in step one that suits your life style, while still giving you proper bass response, it's on to step two. Please be sure you have taken your time to explore step one to it's fullest, without impatience or hurry, or else, don't blame me if it doesn't work.

STEP #2 ESTABLISH `STAGE WIDTH'
Take the speakers along the axis you have chosen in step l and, ONE AT A TIME, have someone move them distally (toward the side walls) WHILE LISTENING. You will notice that the "stage" gets wider. At a certain point you will experience a "center stage weakening" and then you have gone too far. Move it, or them, proximally (or toward center) a hair to re-achieve good balance.

STEP #3 ESTABLISH EXACT `FOCUS'
By focus I mean exactly like with a camera, the performers will come into focus. And this definitely takes two people.

 


FIGURE B
speaker placement axis of rotation

 

Have the other person rotate the speaker, ONE AT A TIME, in a rapid fashion (like tuning a guitar), on the axis indicated by the arrows in figure B, while the listener checks for focus. After a small amount of practice the listener will say "right there, right there!" Then do it on the other side. Have faith in yourself, you WILL hear it.

STEP #4 ESTABLISH STAGE `BALANCE'
We have all experienced some rooms that seem to impart a great stage presentation on one side, but a smaller and less dominant one on the other side. To correct this phenomenon, the (other person) FIGURE C would

 


FIGURE C

speaker placement stage balance

 

move that speaker which is on the weaker side of the stage forward along the axis chosen in figure B, the "focus" step, in 1/16" to 1/8" increments until "stage balance" is achieved. By the way, there is a rumor going around that Audio Physics speakers must be set up in this fashion. This is absolutely not true. They, as well as many other brands, will benefit from this procedure (actually the listener benefits, not the speaker). They will be affected neither more nor less than any other well designed brand speaker.

Again, some of the steps in this method will probably not work on loudspeakers with phase problems, or with complicated crossovers, and that's life. Back to the rule of thirds??

To briefly touch on some other room problems, I would say the biggest culprits of defocusing the musical images are the four corners between the walls and the ceiling, as well as the corners themselves. These are a good place to start treating with Michael Green's "Room Tunes". If you want literature on the subject of "Room Tunes" you can ask, fax, or write Sound II for it.
"DOTS" from Marigo work very, very well to tweak the room with finishing touches, particularly on windows, but on equipment as well. 

                                                                Leo

 

Notes:

(1) In a subsequent conversation, Leo noted the different effects different setups have on bass response: the 1/4 and 1/2 positions improve low bass performance (under 50 Hz.), while the 1/3 position improves mid bass performance.

(2) See "Basic Stereo Loudspeaker Placement," for a basic placement recommendation, if you do not have a dedicated listening room. See "Surround Loudspeaker Placement," for recommendations for surround and home theater loudspeaker placement.

(3)The opinions expressed in the above article are those of the author, Leo Massi.