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Sure, Stephane, give it a shot. Putting the subs at the midpoints of opposite sidewalls, as suggested in the Harman paper prepared by Dr. Toole and his colleagues, would cancel and/or avoid some of the room resonances, plus giving a 3db boost in loudness.



Right on. Just a small clarification, a pair of colocated subs add 6db of extra output due to mutual reinforcement. As you place the subs more than 2 metres away from each other the output from coupling diminishes at certain low frequencies but you should get more than 3db unless you have a very large room. The actual amount of extra output outside of the 2 metre boundary will be between 3 and 6db. If you add a third sub ideal mutual coupling will give another 3db for up to 9db in "free" output and a fourth sub ideally placed will give to 12db. I use a colocated test to make sure each sub is functioning properly, ie not wired out of phase or outputting less than spec. In my room with 3 subs I get about 7-8 db more combined output which means I need to level each sub to 65db.

John