Positioning and Listening distance

I suspect one of the reasons that simple equations seem to under estimate the distance to sit from speakers is because the calculations assume a point source for the speakers. The larger the speaker or the speaker array then the less accurate the calculations will be.

For Dds_hifi: be sure that you use open cell foam for acoustical absorption. The problem with small rooms is that since they are small there isn't much space for absorbing materials. In a 12x12 room I would expect that you will experinece a strong resonance at about 45Hz at the walls if your speakers go that low or if you have a subwoofer. Absorption will not solve that problem if it exists.

My room is aproximately 14x15 with an average 9.5ft ceiling with a sitting position against the wall. The resonance at 37-42Hz is unbearable. Playing something like Clapton's "Unplugged" is an instant headache. The only reasonable solutions are to use a notch filter(1/3 ovtave or parametric equalizer) for the subwoofer input signal or turn the sub off for music. I chose the equalizer and it works fine. Good luck!

Interesting, Sean. I have found dynamic dipoles to be the most difficult to position following speaker placement fundamentals. Dipoles subscribe to the multiplicity of drivers (and bigger physical size) you refer to.
The lower register is an example. For one, the direct waveform @, say, 20hz is quite long (hence, room size??); also, up to a certain listening level, our ears are comparatively more sensitive to the 300-3000hz range. Conventional wisdom leads us to play with distance from the back wall in order to find the best sounding spot vs. our listening position. This would be either, the distance where the waveform is complete (vocab?) or, the best sounding compromise between direct & reflected sound. If the room is small, as in doclb & dds' cases, achieving this is very tricky affair.

With a dipole, the waveform is dynamically reproduced (albeit, in X degrees phase inversion, depending upon speaker design) from behind too -- adding to the waveform length through the back wall reflection... and, I think, to complexity and the need for a larger room!

Which brings me back to the original question. My experiential conclusions (pls note, I can't provide scientific explanation) regarding larger speakers w/ multiple drivers is that these need comparatively *more* energy in order to perform optimally i.e., reproducing signals as they were designed and tuned. In turn, such speakers *produce* more energy at optimal operating level, exacerbating room-induced anomalies. Indeed, in my experience, the worst anomaly has been that such speakers *drown*, rather than "are drowned" in, a small listening room.
I have found this happening regardless of speaker sensitivity...
Numerically speaking: my present speakers have 8 drivers each. Assume I *am* providing enough energy (amp current) to get the drivers operating well together. How do I fit the sound *quantity* into a less than text-book room? By compromising in reproduction spectrum: controlling the lower register, damping highs... whatever.

BTW, Sean I too have found that the further away the listening position, the more room acoustics enter the musical equation -- but I get that lower register OK... Difficult to win on all accounts.

Sorry for the lengthy diatribe!

I was considering starting a thread asking simply how far apart people's speakers are...
While doing some math for my ~12 foot wide room, I found that the Cardas method puts the speakers only five feet apart. I set them there anyway just to try it and confirmed that that's just too narrow. The soundstage was all cluttered, for my taste anyway. So I decided to keep them six feet apart as a constant and tweak everything else as best as possible. I have sound proofing I can place for the side walls that gives me some flexability, at least with the reflection. My room is so crammed with furnishing and crap that I have yet to experienced any obvious trouble with resonances.
I set the listening position in an equilateral triangle as a starting point, but with slight toe-in it sounds really good there, so that's where it's staying.
I'm just wondering how far apart people keep their speakers, and how many people can score a room wider that 12' for this.

Grungle, we must have posted ¬simultaneously. My speakers are 7ft apart, with slight toe-in, against manufacturer's instructions (closer & no toe-in).

My room is 14x18x8, with a 5' doorway behind my chair on the back wall leading into a smaller room.
I sit in a 7.5' triangle, 8-9' out from the front wall
(grand piano behind the speaker plane), and can assure you that I have an incredibly DEEP soundstage that also is wider than the speaker spread. Sidewall reflections are tamed by
stuffed sofa and chair against sidewall reflection points,m sometimes with a throw-pillow propped on top. Flipping the piano's music desk downward significantly eliminates imaging vagueness. This nearfield arrangement works superbly to eliminate room-induced problems, but only with speakers that cohere nicely in the nearfield. I was VERY unhappy with the N803 in this regard...surprisingly incoherent! I blew all my $$ on Parsifal Encores. Their superb midrange is crossed extremely (150/5500hz), so lobing issues are minimized. The (front-firing-arranged) woofers are quick and potent enough to be flat in-room to 30Hz! Toe-in to reduce sidewall splatter and widen sweet-spot a bit results in a little 6-8k heat, so many CDs sound too edgy, but I live with it.
Other speakers demoed included Aeriel 8 (way too bass-heavy), Aeriel 7b (not bad), Thiel 2.3 (too lean), Fidelio (rear-firing woofer anemic when way out from front wall), and Revel F30 (SUPERB midrange, esp for the $, but poor WAF in New England Arts & Crafts decor, and lumpier bass).
To repeat: although I sit only about 6 ft from the speaker plane, I "see" images routinely way back to the front wall
(16'), and sometimes outside into the front yard bushes!
It's clear that near-field listening ENABLES, not PRECLUDES
huge soundstage depth, while minimizing room reflection problems and POSSIBLY lumpy bass nodes. But ya gotta find speakers that cohere in a short distance. Good Luck.
Ernie