How far apart do you position your speakers ?

The 83% rule doesn't seem workable in my room. Is there any theory behind it? It seems a rather arbitrary number.

I have no symmetry in my room, so I try to keep both speakers and my listening position at least 4 feet from any boundaries, since I can't even up any early reflections by symmetrical placement.

I sit about 10-15 cm further from my speakers than they are apart (about 2.56 m). I find I prefer my Vandie Quatros to be at least 8 feet apart for soundstage width. I like to be close enough for an immersive soundstage, but not so close that it becomes "heady".

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