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In Reply to: RE: George Louis posted by Todd Krieger on August 28, 2014 at 15:15:59
Don't forget the crossover.
All filters affect the phase, a low pass has an output whose phase lags behind the original signal while a high pass advances it.
The shift is 45deg per pole in either direction. Consequently a 12dB/oct (two pole) 2 way crossover requires either the tweeter or the woofer to be inverted so that bass and treble are in phase with each other because the low pass retards phase by 90deg while the high pass advances it by 90deg.
90 + 90 = 180 hence one of the drivers has got to be inverted to maintain correct polarity throughout the speakers pass band.
Any suck out observed means that the output of woofer and tweeter are NOT moving in the same direction.
Follow Ups:
The physics is quite complex.... Ideally, when testing drivers/crossovers with square waves, the rise time of the LF driver should acoustically cancel out the "droop" in the HF driver..... The end result is a near-perfect square wave. The hard part is getting both the square wave response and the frequency response correct.
The speed of the woofers rise time is determined by the crossover point.
A fast rise time is an indication of high frequency content. To reproduce a perfect square wave (impossible in reality) you would need a system with infinite bandwidth.
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