How far apart do you position your speakers ?

Daverz,
As I stated above, I hadn't heard of it either, I have done many set ups recently and did the math after reading this thread. You will also read that I went back to the Cardas Method. I really recommend that you start there. Many have talked about the triangle, but there are several room measurements that help your speakers placed correctly realative to room boundries. I figured every one of them before placement, my finished results are very good. This doesn't work for everyone, but it has a very high success ratio. I have attached the web page below.
Good luck, Tim

http://www.cardas.com/content.php?area=insights&content_id=26&pagestring

My room is too irregular in shape for any geometric speaker placement method to work, though the irregularity may also work to break up modes.

Same / similar situation to Dave.
9 sided, completely asymmetric listening space. My panels are on 1 of the short walls, spaced 30->35" from the 'front' wall and about 6.5' apart, inside edge to inside edge. RH speaker has no wall near the side while the LH speaker loads into a corner....about 3' away. The sub is located near this corner, too. The ceiling is 'vaulted and about 11' high at the peak. 2 walls are at 45 degrees. The short wall opposite the speakers....maybe 24' away has a small tapestry hanging on it to diffuse and eliminate a slap-back echo I had when doing the initial installation about 24 years ago. OUCH!

A real mess, and no 'method' I can think of but trial and error works.

But accommodations have been made. I listen to the 'wrong' side of my panels and with the tweeters 'in' everything has gell'd. Bass is pretty uniform and the only problem is in the computer room....which is real boomy.

Hard surfaces reflect, corners or any angles amplify. The cardas measurements are really there with these things in mind. If you are 30 to 40 inches from any wall you are normally ok, less than that and you have a risk of bass being boosted or if firing forward, reflections. With a tow, this reflections are normally not a problem.
Corners on subs are normally not a problem if crossed very low... 40 or 50hz, you can normally tweek things with phase, volume and frequency controls, when you get near 60, this is an natural room amplifying frequency and above that is much harder to deal with.
I hope all of this helps, Tim

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The 83% isn't a rule.

It's simply an observation made after having done hundreds of successful installations around North America and at shows.

If x is the distance from your ear to the tweeter plane (our source of directionality), then y (in this case 83%) is the distance from the center of one tweeter to the other.

When speakers are too far apart, they can begin to sound too thin (although they image great). But do great-imaging-but-slightly-thin sounding systems involve you in the music - as opposed to the the sound?

Too close together, and the imaging suffers excessively.

The last system I voiced ended up at 88%. The distance is ALWAYS arrived at by listening, and sometimes we measure just to see how it turned out. But I've never been personally engaged by music that's harmonically threadbare, as opposed to rich.

Toe-in also effects that separation number, IMO, as well the dispersion of the loudspeaker, not to mention first reflection issues.

I often suggest a starting point somewhere between 80-85 (and up to 90) percent. But always, only after finding the best listening seat location ("best" meaning smoothest bass).

An equilateral triangle (y = 100%) or greater can yield uncanny imaging. But, IMO, a boring musical experience.
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