Distance from the speakers to the seating position

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

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

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.

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

check with the mfg.

mike

yep, all good info above.
Basically, it's all situational/system/room/gear dependent!
Some speakers need more distance from the listener. Some speakers can be placed further apart ingeneral, all things equal. While others need closer spacing, regardless.
I've come across it all. Alot has to do with, yes, crossover desging(gernerally 1st order neeeds more distance from drivers to listener, 4th is the opposite). Also, driver spacing and layout(many small 2 way monitors can let you liten closer often, while multi way, even large Diappolito's need more room to build sound coherently together). And yet, there are more varriables.
I often find, with two speakers only, yes, the triangle gets you in the ball park, at the very least, and you can tinker from there. Some speakers let you sit even closer however. So you must try if you like.
Another often MOSTLY OVERLOOKED ISSUE is room acoustics and set up!...as hinted at above earlier by others.
With a low ceililng situation, or where you're sitting back further, and or you are hearing more reflected sound mixed with direct sound from your speakers, you will be dealing with acoustic issues that will blur and smear your imaging, detail, dynamics, soundstage, and coherency! While in the opposite scenario, if you sit proportionately closer to your speakers, in relation to your room reflection points(walls/floor/ceiling), and thus hear more direct sound than reflective sound mixed with the original signal from the speakers, you will get tremendously better results in the afore mentioned areas!(imaging,focus, detail, dynamics, soundstage, coherency, etc). In fact, many people, especially those who use traditional "tweeter over mid/bass driver" design stereo speakers, are much much much better off if they can either strongly deal with their acoustical reflections in their rooms(thus allowing the original signal from the seakers to be heard with more purity), or SIT CLOSER TO THE SPEAKERS!...all things equal. Other more closed "focused designed" speakers offer more flexibility often.
Still, how far that can go depends on speaker design paramaters, and what the manufacture deems is appropriate distancing. It's a balancing act bsically.
So, if I'm using speakers that are designed(most 1st order designs need you to sit further back, depnding on driver spacing...my old Electa Amators had drivers sitting right on top of each other, so it didn't matter) to make you sit further back, you must definitely consider acoustical treatments/reflection points much more critically if you can't sit closer! With 4th order crossover designs, this often doesn't matter as much, and you can sit closer to your speakers, as with other designs.
Basically, you gotta tinker. Good luck

It depends on the room as well. I have a small room, so like most of the people above I sit very slightly farther than an equilateral triangle. But I know people that swear by sitting 1.5 x the distance between the speakers.

YMMV

Rob

Here are a few links for your perusal:

Immediasound Speaker Set-up and Placement. Immediasound is the distributor for Audio Physics.
Audioasylum Article
Setting-up Loudspeakers by Audio Physics
For surround-setup go to the site below. Click on SACD. Look for the link called "Surround Sound Diagram". This diagram was designed by Emil Berliner Studios, the company responsible for mastering all the DG recordings.
Deutsche Grammophon.
Good luck.

Depends on speaker.. some larger speakers must be heard far enough away for drivers to blend properly. I have to sit perhaps 15 feet away from my JBL L-200's.
With my Chario Academy 1's I can sit only 6' away and the sound seems to be best even this close. The closer you are to the speaker the less of the "room" you will hear and more of the direct sound of the speaker. I would imagine with something like Klipch Horns you must sit a good 15' away since they use the room itself as loading.

The manual for my signature 805's says the best location is like Beavis said, at the apex of an equilateral triangle. I always thought I should be farther back. I tried it then and found that it did sound best for me right at the apex.

Give this a try; you might find something that works better depending on your room, but this is definitely worth experiencing; if you are lucky and you have a good room, this will cause your sound image to focus with clarity you might not otherwise hear.

http://www.cardas.com/search/searchlist.php?area=Insights&content_id=29&pagestring=Room+Setup+4

(you may have to copy the web site address and paste it into your browser; make sure you get the full address)

also depends on the speaker- i.e. most of Coincidents' models use a twin midrange setup, or D'Appolito arrangement. You need at least 8 feet from the speakers for proper driver integration...

As a starting point I use a 10 to 11 ratio (10 for the distance between speakers and 11 for speaker to listener position). Probably pretty close to Beavis' recommendations.

Generally speaking, rule of thumb I initally use is to be at apex of equallateral triangle & adjust from there for solid central image. I find my speakers central image sound slightly better if I sit slighty back of apex of eqilateral triangle. Try to be as accurate as possible. Adjustments of an inch or two are audible. Is easier to measure twice & move once during setup. Good luck!