Does impedance of a speaker change when one bi-amps?

Assuming the crossover is split, yes.

So in a typical two way the tweeter impedance will go to infinity in the bass,
and the opposite in the woofer. The impedance will rise to infinity in the treble.

Of course, that "infinity" may be at 1 Hz and 1 MHz, so in the actual audible range you'll never hit it, but 30-100 Ohms maximums are not impossible.

If you want to play with this, using a crossover simulator like XSim and designing a very basic crossover will help you see what is going on.

Best,
E

Forgot I have a blog post for this:

https://speakermakersjourney.blogspot.com/2016/12/crossover-basics-impedance.html


Best,E

Thank you.

Beside the advantage of a bi-amped speaker presenting an impedance of less variation to each of the two power amps than one amp sees from a non-bi-amped speaker, the speaker’s drivers are also connected directly to the amps, not to the speaker’s internal crossover components. Bi-amping is usually (and best) done with an external electronic x/o before the two amps.

Beside the advantage of a bi-amped speaker presenting an impedance of less variation to each of the two power amps than one amp sees from a non-bi-amped speaker

Sorry @BDP24 this is not really true as you put it. See from my blog post and any simulation, the min to max impedance is MUCH greater with a split crossover.

The overall current load however is always decreased. This may help the power supplies stiffen up.

While active bi-amping is good, it’s also complicated. It’s much easier to get top of the line parts and design in a passive. Do what you like, but it’s no free lunch. It is however preferred in pro environments as the dynamic range and amplifier to output is improved. Need less total watts for the same SPL.

Best,
E