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811B 2-way: OPA227 2nd order active x-over ...
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Posted on August 13, 2014 at 19:09:04 | ||
Got an active 2-way x-over with OPA227 op amps together for 811B/D250P-8 & 55-1220 mono speaker project. Used target acoustic response in ARTA to set 2nd order 1.2KHz Butterworth HP LP slopes, then measured at listening position/ear level/9ft back from speaker. The LP crossover was right on at 1.2KHz , but the 811B horn was crossing over at 800Hz. I had to adjust the electrical HP to 3.18KHz to get the acoustic HP of 1.2KHz. Not sure why the horn response was off by so much and the woofer was on target. I moved the horn back 4" on the woofer box in a crude attempt to time align the drivers. Just listened to some familiar music tracks until the woofer and horn seemed to blend together OK. I would guess that the horn driver is about 8" back from the woofer voice coil. I am aware there are more exact ways of doing this, but have not tried them yet. Not sure the exact phasing at the x-over point either. Electrically, the LP & HP are 180 out of phase at the crossover point as measured in ARTA. Not sure what happens in room at the listening position. Playing around with the comp. cap and padding. Using .47uF/25 ohm now. |
Thanks I'll give it a try. nt, posted on August 15, 2014 at 11:49:33 | |
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Joined: June 16, 2006 |
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