speaker recommendations for a 12 x 12 room?

Iplaynaked, I realize that using large-diameter woofers in a small room is counter-intuitive. But then much of audio is counter-intuitive. For example, my suggestion to rotate the speakers-plus-listener triangle by about 20 degrees (resulting in asymmetry relative to the room's walls) is counter-intuitive, but Bdgregory found it to be beneficial.

Some of the acoustic challenges presented by a small room can be addressed through good radiation pattern control without over-emphasizing the bass region; in fact, those are two different issues. Some speakers systems with good radiation pattern control would have too much bass for a small room, and some would not.

In my opinion two issues need to be addressed in the bass region. One is the room-induced peak-and-dip pattern, and the other is room gain. I mentioned introducing some asymmetry to help smooth out the peak-and-dip pattern; to address room gain, you do not want a "flat" speaker; you want one with a gently downward-sloping frequency response. Typically, a sealed box will do a better job of giving you such a gently downward-sloping response curve than a vented box will. But... not always. "Typical" room gain is a 3 dB per octave rise below 100 Hz or so. If properly designed and tuned, a vented box can have a response that is essentially the inverse of that 3 dB per octave rise - and this can rival or surpass a sealed box as far as natural-sounding bass goes (a 3 dB per octave downward slope is impractical if not impossible for a sealed box). I personally favor bass systems that are somewhat user-adjustable, as the low frequency acoustic environment varies enormously not only from room to room, but from place to place within a room.

If designed to do so, a rear-ported box can give unusually extended, natural-sounding bass even when placed in or near a corner. Audio Note designs their rear-ported speakers for corner placement, and while I do think their specs are somewhat optimistic their speakers sound quite good in the bass region when set up as recommended. It's a matter of designing and tuning the speaker for its anticipated environment.

Duke

"But then much of audio is counter-intuitive"
Er, what specifically do you feel are "hard and fast rules" that are counter-intuitive, as you say? I believe everyone here would like to know, actually. I would

"Typical" room gain is a 3 dB per octave rise below 100 Hz or so.

Room gain is going to add bass boost to frequencies that are bellow the frequency,who's 1/2 wavelength is larger than the longest distance in a room (diagonal). This is going to be frequencies bellow 40hz in this room. Again, this is a better blend for smaller speakers with smaller woofers, not larger woofered (and most always lower extending speakers). Basically, larger frequencies aren't going to be properly represented in such small rooms.
I think most every acoustical engineer is going to concur, that in a small 12x12 room, smaller speakers (with most likely smaller woofers), that don't play super deep, will do better in a small space balancing in the room, basically. That's my input.
Also, since he is likely hinting at putting speaker nearer to walls than possibly ideal, I think 6db per boundary gain will make larger woofered and deeper responding speakers too boomy, indeed.
But he'll have to let us know how that works out for him...

"rotate the speakers-plus-listener triangle by about 20 degrees..."

Moving things towards a corner placement could indeed work out in a single seatting 2 channel setup, yes. But the speakers and response needs to measure pretty equal, and have an overall flat response curve to work. If that does, you're good! (as long as you deal with reflections, and normal aocustical treatment issues.(basically,all that's needed to build good sound in the setup.)
However,one of the main issues here would likely be that moving speakers and seats in this fashion, from an ideal standpoint, is that you'll most likely end up not being able to get similar response from speaker to speaker from the listening position. That's one of the main setup fundamentals that needs to be addressed. And that would be a main concern in any setup!
Simply stating that "moving speakers "20degrees", one way or another is NOT a hard and fast rule to properly setting up speakers!- I assure you. Yes, you could end up with good results, if your lucky.
But like with anything, it all ends up mattering what works and sounds good.
Still, you need to make sure that any setup offers flat response, from the overall system resonse. If not, you'll be up and down on the volume when things get too loud and boomy!...hearing too much boost at certain frequencies, and have an unbalanced sound. (I garantee no studio or well setup commercial cinema is far off of flat response for maximum accuracy and dynamic range - no matter what any audio witch doctor says)
In a 2 channel setup however, in an asymetrical room, there are benefits to getting your seat out of the middle of the boundaries, maybe off center. In this case, yes, your approach could end up working out. As long as the measured response is fairly even between both speakers, and they don't en up in "holes" or abnormally large bass peaks, and in relation to one another.
Overall whatever he can set up in his room, and attain BALANCED (yes, relatively flat response) sound, a properly distributed soundstage, overall sharp, detailed, dynamic sound with good sound-staging, then, he'll be good.
I still belive if he sticks with reasonable sized speakers, he's better off. But, if he goes larger, he'll have to adress the boomy bass, too slow sounding thick bass energy in the room, and, of course, bass modes and peaks and such.
Actually, integrating a sub with an EQ is always an option (that way you can tune the output of the sub, and EQ it to blend pretty descent.
Full range speakers don't give you this option so much.
Yeah, whatever works for yaz.....

Oh, as for the ported speakers working better than sealed speakers in his setup, I highly doubt that! most ported speakers are going to have a bass bump just above where they fall off like a rock in the response. Yes, sealed gently extends, and goes deeper, all things equal. Putting that bass boost near a wall in a room that already offers some bass gain (if it plays low enough anyway..which why I said he should stay with smaller speaker designs, wiht likely smaller woofers, yes), and then having it drop off, will be more likely to offer a peaky response curve, at best.
BUT, again, whatever ends up working for ya. The end results will speak for themselves, to be true.
That's what's fun about audio, is that it's not all science, but some witch doctor'y as well

Hey, he should post this question to guys like Richard Rives Byrd and Robert Harley, and see what they recommend from their thousands of systems worth of setups. I'd be interested in their input, and what speakers and setup they recommend
Peace....

Iplaynaked asked:

"Er, what specifically do you feel are "hard and fast rules" that are counter-intuitive, as you say? I believe everyone here would like to know, actually. I would."

Well, that's not really what I said. I said that much of audio is counter-intuitive.

Okay, I don't know if these facts are so widely accepted as to be considered "hard and fast rules", but I think they are counter-intuitive:

1. Total harmonic distortion figures fail to reliably predict subjective preference.

2. The perceived tonal balance of a loudspeaker can change with loudness level even if the measured frequency response curve stays the same (Fletcher-Munsen curve; this one might qualify as a "hard-and-fast rule").

3. The on-axis anechoic frequency response curve is not a reliable predictor of perceived sound quality or tonal balance.

4. The ear largely ignores reflections arriving later than .68 milliseconds after the first-arrival sound as far as directional cues goes, but takes into account these same reflections as far as tonal balance and loudness goes.

5. Semi-random distribution of multiple low frequency sources in a room results in smoother bass, both measured and perceived, than careful placement of a single low frequency source.

6. The ear perceives sound quality very differently from the way the eye judges a frequency response curve; narrow-band peaks and dips that leap out to the eye are often inaudible to the ear.

7. The ear has a characteristic called "masking" that tends to ignore a low-level signal in the presence of a louder signal if they are close in frequency. This principle is applied in audio data-compression algorithms.

8. This principle of masking works in the frequency domain but not in the time domain, so that if the low-level signal is a distortion that arrives later in time, perhaps because of a path lenth difference (as with diffraction), then it is much more likely to be audible.

9. Speaking of diffraction, this is a type of distortion that our ears have a level-dependent sensitivity to; that is, we don't hear it at low volume levels but we do at high volume levels (as a harshness) - and this is one of those distortions that is not revealed by a frequency response curve.

10. The ear is relatively insentitive to the preservation, or lack thereof, of the phase relationships in a music signal. I'm not saying it's undetectable, but certainly not as readily detectible by the ear as by a microphone.

I could go on, but ten seems like a reasonable number to stop at.

By the way, I am not advocating 20 degrees of rotation of the speaker/listener triangle as a "hard and fast rule". It is an application of a principle to a specific situation. I trust that a re-reading of my posts in this thread will reveal what that priciple is. Being able to apply principles is more useful than memorizing rules, because the "rule" may not be practical to apply in the next person's room, but perhaps the principle can be applied in another way.

Regarding what size drivers and what type of box a speaker should have in a small room, I think you are arguing based on generalities that apply to most speakers, and I'm saying that if done right the specifics of a more nearly ideal solution in this case are different from what an overview of generalities would predict.

Duke
dealer/manufacturer