^ ^ ^
Good point, and perhaps I mis-spoke.
whatever model one uses, the Geddes approach, the Harman, Welti/DeVantier method, your own home brew technique, it largely doesn't matter as typically practicality intervenes and often influence sub placement
I intended, that whatever you set out to do, whatever model you may intend to emulate, oftentimes the actual locations used are dictated by influences other than the purely technical ones that you originally set out with, ie., practicality/aesthetics, etc.
So personally, I recomend as much dedicated control as possible. Individual circuits for each location, thus facilitating differing adjustments for each sub. Regarding the Welti-DeVantier positioning, ... if one's subs are all mid-wall, or some up front and some in the back, due to a variety of residential factors, it's entirely possible you may be significantly closer to one group or another. From there, if individual control is called SFM, then that's cool too. It's audio, individuals have been time/signal aligning multiple sources for years. I've never read SFM with any amount of real attentiveness. A re-read is in order before I continue off ill advisedly. I get it, it seems they all want to stake claim of their specific "process", everything has to have a name.
I've not really paid close attention to other multi-sub techniques, and actual actual methodologies. For HT, it seems there's so few actual documented in use implementations, with measurments, data, and solid results.
The approach I posted, was forged out of both discussions w/pros and audio enthusiasts, and my interest, background, and reasearch in pro audio. In the pro world, the blending of multiple sources, time alignment of delay towers, cardioid sub arrays and signal manipulation, wavefront shaping and main lobe broadening so that you project as much LF into the primary LP and away from the performance mics, all is well vetted and firmly entrenched in use. There exists a great deal of well documented examples in whitepapers, AES submitted work, and the like.
I'm not truly well versed in much of it, and I've not used all the techiques either, not even close. But I have tried to read and experiment with as much as I can. However taking all that I'd learned in that regard, and adding forum readings and discussions w/MSeaton, I recomend the approach I layed out above.
Control and manipulate as many elements as possible. I mean it only makes sense, as long as the signal processing is transparent, the more control the better. We strive for a smooth, fully time/phase coherent response. When the output range our subs cover, benefits from such efforts to aid in evening out the response, both measurably and subjectively, then clearly this becomes worthwhile.
I just thought of an analogous example;
The entire process seems akin to internet/LAN packet switching, ie., the original signal is fractionalized, spread across a paralleled network that's optimized for robustness, then fully re-correlated or re-constituted for end use within the primary listening area.
It's funny because I just thought of this, my son and I were recently watching/discussing an ARPANET piece, and Kleinrock, the dude that wrote the book, and built the first packet swiching gear connecting UCLA, and Stanford, I believe
I sat down at a Harman SFM demo while attending Cedia last year, and was perplexed at some of the things the presenter said to me, what a joke. He was dumbing it down for mainstream consumption, and I listened to the entire thing. I had some very specific questions but he insisted not going too deep. I understand, but at that time, it was just two of us listening to his presentation. My only guess was he was well versed in the demo, but nothing more. I stayed polite and didn't push.
Kevin Voecks, Harman big shot, was in the booth too, but he was wrapped up smoozing, etc. I wanted someone to address my question but I decided to move on. The presenter (I'll have to review my notes, .. Todd something, not Welti) sugested I go accross the street to the big Harman demo at the neighboring Westin. He tuned the $400k total, $270k audio, SFM multi-sub, M. Levinson powered, JBL Synthesis 7.1 system. This guy explained to me the best area of couple seats, as that's were he tuned the room from.
So later that day, I went to check out the demo. I got one of the two prefferred seats, quite excited and unfortunately, it was all for naught .... it was terribly underwhelming. I posted details shortly after the show in some AVS discussions. It was not what I thought would be representative of a Harman $400k tour de force, especially in context of the Harman brass overseeing the entire affair, .. oh well.
Here's my post wrt the SFM demo; http://www.avsforum.com/t/1413241/room-correction-vs-digital-signal-processors/30#post_22388617
I mean come on, a decent room, JBL beryilium drivered / Levinson powered, four, corner loaded 18s, ... good mid-bass but it ended there. I don't have a clue ... right upstairs in a private room was a superb system set up by Dan Francis, and the gentlemen from XTX. It, had it all. The Harman/JBL demo, ... junk. It was a shame too, I'm a fan of JBL and all the R&D they put up. I wanted to try to take in the demo again, but they made you get a ticket at the booth (diff building than the demo), I never came back, too much other good sound to be experienced....like Steinway Lyngdorf. That's a multi-paragrapgh post by itself,...best loudness, dynamics, transient attack, I've ever experienced ...anywhere, period. All set up by Lyngdorf, I got two front row center demos, and discussion w/Lyngdorf. All that a short walk from the JBL demo,...no contest. The JBL room, ain't nobody got time for that
. Even better, the remix
All the best