Distance from the speakers to the seating position

depends on speakers...my alon were a equal distance. my audio physics are closer.

check with the mfg.

mike

I use ProAc Response 2.5s, but don't have them set up exactly to ProAc spec. I like being able to slightly see the insides of the cabinets when they're facing me, rather than pointed straight at me. And I sit in a chair with castors so I can roll back and forth depending on if I want a closer, more intimate listen or further back to simulate being further into the audience. By in large, my set up is an equilateral triangle and is varied by my seating choice.

In general, I would start with the manufacturer's recommended set up, then adjust from there according to your taste.

All good advice, Eandylee, every word.
I like Newbee's 10:11 ratio- I'll have to try that!

When we go into trade shows into an unfamiliar room, we first pace off the room in the following way:

With the speakers a few feet off the back wall, and a few more feet from the sidewalls, examine the distance left between the speakers' centers. Let's assume that to be 9.5 feet for example.
Place the chair (your ears) then 9.5 feet back from the midpoint of that line between the two speakers.
We call this an "equal-legged Tee" layout, and it works for our and many other direct-radiator speakers.

The speakers are likely toed-in of course, not quite looking you in the eye.

With the speakers' 3-foot distance off their wall behind, that 9.5-foot distance from that line then places you 12.5 feet back in the room. Hopefully this does not put you at the mid-point of a 25-foot room, which is where standing wave peaks and dips are most prominent. Or at the 3/4ths point, for the same whole-number-ratio reasons.
60% of the way down the room is cool, and so is just 40%.

If you are indeed at that midpoint of the room's length, consider picking up the entire listening triangle and moving it farther out into the room, perhaps just a foot, so that you are then 10% (or noticably) off-center from front to rear- no longer at the midpoint.

You could instead narrow the speakers' 9.5-foot separation by a foot, and then sit a foot closer.
Or you could widen the speakers' separation by a foot and sit back a foot farther. You would re-adjust toe-in of course.

This is not gospel, but provides an excellent starting point, whereupon you might choose to sit slightly farther back, or move the speakers up to 10% closer together. Certainly you would find that the speakers would not be farther apart than this ratio, or you'd lose the strength of the center image. Also, you would likely find that your opinion of this layout would not be altered much by the music you play or the gear you use.

We also always place 8" diameter, six foot tall ASC Tube Traps at the left and right first-reflection points, and one at the front center a foot or so behind the plane of the speakers' fronts (this "curves" the soundfield into an arc, or flattens it into a plane, without altering the perceived depth).

A large TV set or a rack of reflective stereo gear in the middle would alter any suggested ratios, and so would a coffee table between you and the speakers, or a footstool, a high-backed chair, or the wearing of eyeglasses.

Check for smooth response in the bass, using a string bass recording. We recommend Christian McBride's "Getting' To It" CD. It is also of reference quality on the drums and horns. The distance from the speakers to the wall behind them, and your "off-center position" in the room, are what you'd look at to tune the bass response, of course.

Best regards,
Roy Johnson
President/Product Designer
Green Mountain Audio

Each room/setup/layout/gear selection is different, and calls for different variables to be adressed for best "balance". It's all a balancing act, and all things must be considered together for the overall effect. You simply can't just take a blanketed formula, like an "equilateral triangle setup", or 10/11 whatever, and assume good restults! It's all very situational.
You must tinker and try things.
First thing I always do is FIGURE OUT THE BEST SEATING POSSITION(S)! I find the location(s) where I'm going to get potentially the best frequency response and foundation from with wich to anchor my EARS! If I can get smoothest response from there, I go there...all things considered. Obiously there's compromises often...but then you adjust from there too from the speaker and acoustic treatment end!
Anyway, I then am going to find the coresponding speaker locations up front that offer the best, smoothest, most even frequency response in relation to the seating position(s)! If from the seating position(s) I can get the speakers to yield the flattest and most even response, I've got a solid foundation for accurate, dynamic, natural sound(not boomy, lean, peaky, inaccurate pressentations). If I can't get that, I'll consider EQing the bass woofers if possible to deal with any serious challenges. Yet, I'll most always get the locations for both the speakers and seats working together to give flat response...CRITICAL!
You then must balance those "ideal" or "best" location choices with the soundstage and imaging parameters.(i.e, triangle, width, depth, whatever). If my location considerations for speakers/seats let me chose spots that will yield a setup that has the proper perspective and geometry for a sharp, coherent, solid image, with a good soundtage(width, depth, height, perspective, etc), then you're there!!! Then you need to consdier "toe-in" for tonality and focus fine tuning, as well as "aim" or "angle" of speakers towards listening possition", etc.
After that, I'm consdering all the acoustical needs, in relation to the set up(speakers and listening possitios). I deal with overall reverb(must study this part), and mostly treating corners for bass/imaging, and FIRST ORDER REFLECTION POINTS PRIMARILY! Once you balance out this part for best absorption/diffusion considerations, depending on room needs(long wall setups can get away with less of this often, while short wall setups usually require much more strongly considered acoustical add on's for good sound!!!!...due to signal reflection/boundary interaction to your ears!...mixing the rooms reflections with original signal).
Other than, in smaller acoustical spaces(most homes sadely), and then employing large bass traps there in, there's really not much more to consider in an average home audio set up! Maybe phase with a sub(s), etc, but not much else!
YOU SIMPLY CANNOT GO WRONG WITH WHAT i JUST SUMMED UP!!!
A solid foundation for flat and even(between speakers) frequency response from speakers/seats, proper speaker to speaker to listener set up(triangle, whatever), proper speaker toe-in/aim, proper phase(if applicable), proper acoustical considerations and/or treatments, and you cannot lose!
Other than bass management and EQing of difficult bass mode situations when applicable, there's not much more. Anything else is trial and error, and season to BEST RESTULTS GIVEN YOUR GEAR AND ROOM!
Good luck