Actually, using 2 different subs (designs, brands, etc.) can be advantageous, as they'll each load the room differently.
I agree that 100 Hz is probably a higher crossover than desirable. I always start at 0.7 x -3 dB point of the speakers. That may seem low (particularly when starting with a 100 Hz crossover, but you don't want to hear the subs. You want to hear a seamless full-range speaker. The low of a crossover point will help blend the subs with your speakers.
Don't be afraid to try the speakers *near* the corners. I was anti-corners until I moved into room where I couldn't get other placements to work. Per the advice of Roy Johnson @ Green Mountain Audio, I went against my "truism" of sub placement for 2-channel audio. I'm glad I did.
Phase-based cancellation isn't necessarily a bad thing - if you use that cancellation intentionally and strategically. In a previous room, I used one sub to remove a node accentuated by my primary speakers, and another sub to fill in the low end.
And now for my most controversial statement...
Seamless sub / main speaker is the typical goal. Don't get me wrong, it's a worth goal. However, you'll know when you have ideal physical / phase placement when the sub performance enhances the imaging of your primary speakers. Crazy, eh? Whenever I read that someone "moved their speakers 1/2" and the imaging snapped into place", I believe that has nothing to do with the tweeter / midrange placement, and has everything to do with how the room is being loaded with low frequency information *synergistically* with mid-range information. You'll know it when you hear it.
I agree that 100 Hz is probably a higher crossover than desirable. I always start at 0.7 x -3 dB point of the speakers. That may seem low (particularly when starting with a 100 Hz crossover, but you don't want to hear the subs. You want to hear a seamless full-range speaker. The low of a crossover point will help blend the subs with your speakers.
Don't be afraid to try the speakers *near* the corners. I was anti-corners until I moved into room where I couldn't get other placements to work. Per the advice of Roy Johnson @ Green Mountain Audio, I went against my "truism" of sub placement for 2-channel audio. I'm glad I did.
Phase-based cancellation isn't necessarily a bad thing - if you use that cancellation intentionally and strategically. In a previous room, I used one sub to remove a node accentuated by my primary speakers, and another sub to fill in the low end.
And now for my most controversial statement...
Seamless sub / main speaker is the typical goal. Don't get me wrong, it's a worth goal. However, you'll know when you have ideal physical / phase placement when the sub performance enhances the imaging of your primary speakers. Crazy, eh? Whenever I read that someone "moved their speakers 1/2" and the imaging snapped into place", I believe that has nothing to do with the tweeter / midrange placement, and has everything to do with how the room is being loaded with low frequency information *synergistically* with mid-range information. You'll know it when you hear it.