Hi Mike, Tom, jfc and others,
Sorry that I've taken a while to reply on this thread. My wife and I took a long weekend at our cabin in Maine--no internet access there. Ken and Tom sent emails to alert me, but I didn't see them until after I got back. And I needed to get my facts straight before making this long post. (always a good plan)
Let me summarize what I have heard so far. As jfc noticed, Mike's good experiences with four L1s in stereo are in contrast to our stated rule of avoiding distributing a single source to multiple L1s. And this rule also contradicts what Mike has heard from four Bose people, that it is okay to distribute to two speakers if you observe a 4 foot minimum spacing between them.
Let me tackle the "4 foot rule" first. Tom would like to know where this comes from. You may find the answer amusing. First of all, I found no reference to a 4 foot minimum spacing anywhere on the forum, other than in this thread, and it does not appear elsewhere on the Bose web site that I can find. So far, so good. But, by coincidence, the number is familiar to me in another context. More than 15 years ago, Ken and I worked in the installed sound part of Bose Pro. Dealers were beginning to hang clusters of multiple 402s, 802s, etc. because it saves them money to use fewer hang points. We were very concerned about coloration from interference, in other words the "phase cancellation" often referred to on the forums. (I don't like the term phase cancellation, but that's another story.) Ken and I decided that those speakers needed to be no less than 4 feet apart, or the amount of coloration would be unacceptable in some seats. This gradually became something of a standard distance, which is too bad, since it represents the worst coloration we were willing to tolerate. And I remind you that this rule applied to directional speakers aimed in different directions and falling off with distance at the normal 1/r^2 rate.
Interference between line arrays would be more severe. In fact, the current Bose design rules for installing MA12 line arrays recommend NOT putting them in the same cluster at all, ever. For distributed systems, they plan to recommend a spacing between line arrays of between 6 and 15 meters! (20-50 feet) So the amusing part is that the source of the "4 foot rule" appears to be Ken and me, although the rule was never meant to apply to line arrays. The four Bose people who told Mike that 4 feet was okay were "incompletely informed" and assumed that the rule we taught them applied to line arrays as well. I've spoken to our head of training for North American Pro to let him know that the curriculum needs to be more explicit that the spacing rules for line arrays are different, not 4 feet. (Mike, if you remember the names of any of the four folks you spoke with, please send me the names in a PM, so that I can be sure to teach them about the different rules for line arrays. No, they aren't in any trouble, Bose isn't that kind of workplace. Help me fix this if you can.)
So much for the 4 foot rule. It works for 802s and such, but it does NOT apply to line arrays. (All the way from Colorado, I can hear Tom breathing a sigh of relief.
But maybe now Mike is shifting from foot to foot?
(continued on next post)