What’s the Right Power Amp Ratio For Bi-Amping?

The question boils down to this: if you had the ability to measure power consumption of white noise (equal amplitude across the audible spectrum, not necessarily 20Hz to 20kHz, if you could do it for 50Hz to 10kHz that would be a sufficient demonstration) by the two halves of a bi-amped speaker, what would you see?

Since the crossover point between the low frequency section and the mid/hi frequency section of a speaker will almost always be in the lower part of the 50 Hz to 10 kHz range, most of the energy of white noise occurs at frequencies that would be above the crossover point. So most of the energy of white noise would be delivered to and reproduced by the mid/hi section of the speaker. The spectral composition of music is very different, of course.

With music, per my earlier comment, if the crossover point of the speaker is 350 Hz both amps would typically have to supply approximately equal amounts of power. If the crossover point is significantly less than 350 Hz the high frequency amp would typically have to supply more power than the low frequency amp. If the crossover point is significantly higher than 350 Hz the low frequency amp would typically have to supply more power than the high frequency amp.

With music this relationship will of course vary somewhat from recording to recording and from moment to moment. Which is why I used the word "typically," meaning that it would hold true the majority of the time.

Regards,
-- Al

I am using one stereo amp on each speaker. Left for mid highs and right for bass cabs.  The meter is always higher on mid highs.  Same amp.  Crossdover point between upper bass driver and lower mid driver is 230hz.

Thanks, Pauleladue.  That's an excellent data point, which most of us wouldn't be able to provide and which is consistent with what I said.

Regards,
-- Al

What units are the meters marked in? Watts or VU or ?

Update:
I’ve located and purchased another NAD 2700 amplifier, so I’ll have a pair of identical amplifiers.

I’ll now have 3 options: vertical bi-amp, horizontal bi-amp, or bridge and power left and right separately without bi-amping. Vertical bi-amping seems to be the preferred way, as mentioned by @racamuti , @almarg and @georgehifi, so I’ll try that first.

Bridging seems too extreme by the way, as I’d end up with the capability to produce 400 watts per channel, probably ten times what I’d ever need during normal listening sessions with my relatively efficient Energy Reference Connoisseur 30 speakers in my 12’x12’ listening room.

I will experiment with shorter speaker cables, from the 8ft 12 gauge cables I’ve used with the 3225PE/3020i setup, I’ll be able to go to 3ft 12 gauge cables with the 2700s sitting beside the speakers. I’m not expecting any audibly noticeable improvement, but maybe I’ll be pleasantly surprised.

Thank you everyone for your input! This is is going to be fun!