One of the merits of biamping that I never hear discussed involves speaker back EMF. Speakers have mechanical resonances. The energy stored in these resonances can be dissapated both thermally and electrically. Just like an electrical motor can be a generator; a speaker can behave like a microphone and feed a signal back into your amp. Because of the long decay times of these speaker resonances, this signal may have little correlation with the audio signal. Now, if all amps and their components were perfectly linear, this would not pose a problem. However, when this 'duplex' signal passes through a non-linear device, these two signals will cross-modulate. This is similar to IM distortion. If you are dealing with a push-pull output stage that has any tendancy to class AB bias, this is a very non-linear operating region. Signals also usually pass through PS electrlytics; not noted for their linear behavior.
If you have read this far, here's the punch line. If you biamp, the back EMF from the woofer will not be able to cross-modulate with the mids and the highs. Since the woofer can store alot of energy (larger mass, longer excursion) in it's resonances, I maintain this results in some audible benefits.
If you have read this far, here's the punch line. If you biamp, the back EMF from the woofer will not be able to cross-modulate with the mids and the highs. Since the woofer can store alot of energy (larger mass, longer excursion) in it's resonances, I maintain this results in some audible benefits.