Very informative post jakeman. What are your thoughts of raising the sub xo if you have dual subs in the front corners? I would think it would be okay because, although the subs are now outputting a frequency that could be localized, since they are in the corners equidistant, it would still keep the soundstage balanced. Also, you would not be relying on a weaker amp to drive the low frequencies.
I tried xo's from 40-150, and the best response I got with 2 EP500's in the front corners was 90Hz in the AVR, subs in bypass.
Good stuff, SRoode. My first recommendation is always to use dual subs because many of the issues we have been discussing disappear. I ran dual EP600s the same way for a year adjacent to the front speakers both in mono and stereo mode crossed at 90 and 100hz to a pair of monitors. The integration and soundstage was breathtaking. I always felt one of the strengths of the EP subs was their superior ability to play music compared to most other vented subs but that presumes proper setup and speaker integration. Plucky string bass and snappy snare and kick drum is what made the EP500 stand out in early blind listening tests with other noteable subs.
No question that a higher crossover makes the speaker amp more efficient and preserves headroom. That alone may make it a necessity for the folks who rely on receivers. But for those with amppower to spare, lower crossover points usually means better fidelity if you have capable speakers like the M80/60s. The other reason I like lower crossovers with single or dual mono subs is you lesson the clash of upper harmonics in music between the sub and the speakers. For HT its not such a concern.
Its an interesting paradox. For better phase integration and soundstage, which is so important for music, the subs almost always work best up front next to the speakers. The Harman paper advocates mid sidewall for dual subs for superior FR but makes no mention of the greater phase issues associated with such a placement. I suppose its for that reason that some designers suggest one sub up front and one in the back of the room 180 degrees out of phase when using dual mono subs. The idea is that way you get more uniform FR and maintain time alignment within the sub/sat system.
