set speakers large or small?

Ojgalli,

Only the abstract of the JASA article seems relevant, and it suggests that the model they tested and human ability to localize LF sounds is poor, especially in other than anechoic conditions. The link didn't get me to the JASA article, so I was unable to see a breakdown of their results, but I'd guess the octave band centered at 125 Hz was by far the most localized.

I did enjoy the reference to the binaural processing model of Lloyd Jeffress. My primary interest when I was a post-doc was binaural processing, and I thought the Jeffress model of neural-spread made much more sense than the equalization-cancellation (E-C) model derived from the theory of signal detection (TSD). Jeffress was a nice guy and helpful in encouraging and critiquing my work. I did a study of the detection of sinusoids in computer generated noise waveforms in which I adjusted the phase of the sinusoid in the noise waveforms. I imagined it would be a crucial test of the theories, and the detectability did vary widely, but not as predicted by either model. By that time, I was losing interest, and never published the work even though I was encouraged by Jeffress to do so.

This research was done with earphones, so we could control the signal that was delivered to the ear, and the lowest frequency was usually 250 Hz. We did have an anechoic chamber that went pretty low, but transducers were inadequate for LF work.

db

wtf are you guys talking about,please come down to my level

Here's a professional and hobbiest experience with all this:
I recommend that you should strongly consider doing what THX found works, and that's to cross over your passive speakers system at 80hz, and let the active sub handle the much more demanding bass dubties - even with larger, more full range speaker systems. This free's up the receiver/amplifier to better handle the rest of the sound spectrum, relieving it of taxing bass dubties. This is especially helpful on receiver systems, with limited current deliver, and with passive speaker systems which offer limited efficiency and control going through passive crossover networks. Overall, you'll have much better efficiency, dynamic power, and range from the system this way.
This must be qualified however in direct respect to a "properly setup" and engineered sytem, fundamentally! Where people run into problems -and thus make all kinds of adjustments to overcome fundamental setup and acoustic issues - is that they most always never properly address issues such as critical speakers and seating, setup, and the acoustics in play, because they don't know what they're doing. As is too often the case, in directly adressing the main question being posted here, is that what happens is speakers will end up in acoustic holes in the bass response, making it impossible to get flat dynamic, accurate resonse from the system. Either the speakers, or the sub, or both will be sitting in a hole in the bass response, yielding a weak bass response. To try and compensate for this, what more often than not happens is that they'll move the crossover point to where things sound fuller. Or they'll crank up the bass/sub to try and overcome acoustic issues - and thus never properly adress the fundamental problem.
What needs to be done is to assure that the speakers are first flat (or at least not in a hole) at the critical crossover reigion. Ahd that goes for the sub too! Then, even with EQ assisting things, you can attain a solid, flat, accurate resonse from the system, with solid dyamic potential and range. You couple this with good bass managment in the above type of system, and you get simply tremendous performance results.
Basically, it all must be taken in context. Everything must balance out. If you ignore or aren't ware of all the issues in play, and don't properly adress things, you can easily make adjustments elsewhere in the system to try and mask over the real fundamental problems.
You can then see why results vary so extremely in regards to setting parameters and preferences from person to person, setup to setup, room to room, and equipment to equiopment. It's simply way to easy to not adress issues such as discussed here, as well as others such as toe-in, aim, speaker spacing, speaker and seating locations, speaker height, acoustics in the room, frequency response, water-fall plot, RT time, phase issues from speaker to speaker and/or seating location, speaker to boundary
interaction, etc, and so on.
Takes time to learn all of this, and it all adds up like ingredients in a master chef's recipie, or an experienced mechanic tweaking a race care.
If you don't know what does what, you're limited in results.

--Pertinent Quotes: "The only source of knowledge is experience" (Albert Einstein)

"It's not that I'm so smart, it's just that I stay with problems longer." (AE)

"Sometimes one pays most for the things one gets for nothing." (A.E.)

"A person who never made a mistake never tried anything new" (AE))

"I think and think for months and years. Ninety-nine times, the conclusion is false. The hundredth time I am right" (AE)

"The important thing is not to stop questioning. Curiosity has its own reason for existing."(AE)

"I am passionately curious about finding the truth" (AE)

To expound a bit further - for all you 2 channel audiophile purists and full range stereo speaker devotees - yes, you're going to certainly get more perfect coherence running a full range speaker system, full range (and maybe adding minimal subwoofer integration to the very bottom registers, .1 configuration, etc, for home theater). A main trade off's here includes getting coherent full range integration of the sound, but most always yields limited dynamics and impact from the system, from relying on typically dynamically limited passive speaker systems to provide the weight and authority to the overall sound. You cross things over with bass management, to an active woofer in the system, and the efficiency and power just went up! You get higher efficiency speakers, and or even active speakers on the top end, and you have even more dynamic range and impact potential!
Of course, again, integrating a separate woofer speaker with your mains, and you will face a trade off of perfect driver to driver integration, from crossover issues, phase, slope, whatever. Still, the trade-offs here - for most all multi-channel/ht applications, far out-weigh the negatives!
Anyway, opinions will vary. But every multi-channel, full range, passive speaker system I've ever heard lacks proper dynamics and impact, compared to integrating an active woofer in the chain - at the very least.

I concur with pretty much everything Queefee wrote, but add this cautionary caveat to his Pertinent Quotes: Just because AE was a brilliant physicist does not imply he was a brilliant philosopher. There are many things I'd rather know through reading, secondary observation, or generalization rather than direct experience.

Palen, the THX rationale is based on the contention that we are not well able to localize frequencies below 80 Hz, a contention I contend that is based on psychoacoustic evidence.

db