GrimSurfer
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- May 25, 2019
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If spec "60-22k Hz +/- 3 dB" is correct I would stick to 80Hz XO point (or even 60Hz) to help energize the room with mains as well in addition to 2 subs. As long as your mains can play 60Hz with decent SPL and THD that makes IMO. LF Linearity should anyhow be dealt with DSP.
I had initially calculated the xo at 90 Hz (see graph) but still had a frequency dip (not a notch) when the sub was set there.
So then I ran REW for the mains only. Then separately for the sub (I started out with one sub). The sub rolled off a little steeper than advertised (don't recall the exact figure, as these are in the notes that are "carefully archived" (LOL) in the crap hole I call an office).
Using the figures, I then recalculated the xo. That came out higher than I thought it would, still not high enough as the pot on the sub was off by about 10 Hz. Fine tuning was done with level after that.
I guess part of the issue is my bookshelf speakers. They handle the mids and highs nicely but aren't so great down low. Many days spent positioning them relative to the back wall for bass reinforcement but one can only expect so much from a ~14x9x8 bookshelf containing a 6" main driver.
That's what got me onto asking @LarsF about his bookshelf speakers. A useable 34 Hz is much lower than I would expect from a passive bookshelf. I could see 40-ish with a rear firing port and corner reinforcement. But traces don't lie, so I can't question his decision to hold off on getting a sub (particularly if his space is average/small, his listening levels modest and the power handling of his bookshelves high).
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