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Okay, so I'm now semi-active bi-amplifying my speakers:
-full range signal from amp(1) goes straight to original passive crossovers; a 6ohm resistor takes the place of the woofer on the crossover network; high-pass to the Atlas midrange driver (Klipsch K55) is 400Hz/ first oder
-second output of the preamplifier goes to Cabre AS45 active crossover, low pass to the second amplifier, 460Hz/12dB. Second amplifier is connected straight to the woofers.
Since first order crossovers do not alter phase, and 12dB crossovers cause 180° of phase rotation, is it correct to reverse the absolute polarity of the woofer cables, so that the signal they reproduce is in phase with the signal reproduced by the midrange driver?
Follow Ups:
"Since first order crossovers do not alter phase"
That's just not true. First order crossovers COULD result in a speaker with linear phase for a mic at some specific point in space, but almost never really do even that. Just throwing a simple crossover at a driver doesn't give you linear phase of the system.
Besides the issue of positional relative delays between drivers, the entire response characteristic of each driver (i.e., both of the electrical crossover network and the raw driver itself) is the 'real' crossover order. Even a "no crossover" speaker isn't going to be linear phase, nature isn't as nice as that.
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Each single pole component(coils or capacitors) introduces a 90 degree phase lag in addition to the phase lag the speaker coil, and it's acoustical center impart. The usual convention is to leave the woofer connected so positive voltage moves the cone forward, easily verified with a "click test", with a 9 volt battery. The upper components polarity are then switched to get the smoothest phase response through each crossover point.
Without testing, it is impossible to say what the phase of your particular component set up is in the crossover region. A simple test is to use a sine wave or band limited pink noise set to the center frequency of the acoustic crossover, the polarity that results in more SPL (sound pressure level) output is the "most" correct.
Depending on how close the components acoustic response and acoustic centers line up, it is possible that either polarity will have little difference in output in the crossover region. For this reason, DSP (digital signal processing)is used, digital delay and equalization can be employed to result in a smooth phase transition through each crossover filter.
Using FIR filters, it is possible to achieve a "dead flat" phase response throughout the entire audio range, regardless of crossover slope.
Cheers,
Art
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