Originally Posted by RicFlair
??? I have B&W 686 S2 Bookshelves - I'm asking because I want to know should I go for a 5.2 AVR or a 7.2 for bi amping.
Originally Posted by lovinthehd
Adding extra terminals and still using the passive crossover components is still just marketing trying to play on the benefits of active bi-amping. The avr still has power supply limitations.
True regarding power supply, but for the OP the question of power supply is still relevant. Whether using the bi-amp function or not, a 7.1 is almost certainly going to have better power supply than a 5.1 if in the same make/model line and might have superior amplification power out per channel also. Not so certain for makes from separate companies with disparity in performance between them.
Quick estimate of 60% of the power supply AC consumption is usually all available for power out to speakers, taking losses and non-power-amp circuitry into account, if comparing modern receivers with typical class AB output stages. Comparing the input power on 5.1 vs 7.1 might reveal that a choice does matter, even if the power per channel is identical and both are rated to drive 2 channels within distortion limits. Comparing dynamic headroom dB might also reveal a difference.
The caveat is that even doubling of power output only amounts to 3dB of extra volume, so it has to be a marginal case of lower speaker efficiency and/or larger room size for this sort of minor difference to matter.
Originally Posted by mmiles
IMHO consumer grade speakers with dual sets of terminals is marketing hype.
Sort of. Some amps with active crossover can still benefit. Any analog anomalies from the crossover are still there because the crossover is still there, but splitting the bandwidth with active crossovers too can improve the power delivery while reducing intermodulation distortion. Even pro active bi-amp might involve 3-way speaker with the mid and treble passively crossed over and driven from a single amp, so there is nothing inherently wrong with such approach. It is a compromise.
Originally Posted by Ak Gara
I think the only reason to biamp would be if the speakers didn't have it's own internal passive crossover, and even then in order to not send the same signal to both drivers, you would need some kinda MiniDSP that let you add an 80hz low pass filter and a 2.5hz or there abouts high pass filter for the midrange driver, and a 2.5hz low pass filter for the tweeter, and a 80hz high pass filter for the subwoofer.
You meant 2.5KHz? FTFY
Your statement reflects the straightforward approach that pro audio applies. Such systems are designed with band-limited speakers similar to consumer subwoofers, but with discrete devices that cover all frequency ranges when combined with each other. The benefits of bi-amp include less demand on the power amplifier output stage and lower level of harmonic intermodulation in the amp and driver.
My receiver will do active crossover, but the catch is if the system gets confused in firmware setup e.g. power failure during setup adjustment, it can actually drive full-band signals to both woofer and tweeter and maybe burn out a tweeter driver. Seen this happen in person but I tested the function using the split terminals with crossover still in circuit and not in danger of losing a tweeter, thankfully. So after experimenting with it I abandoned the idea of ever using a receiver for bi-amp and decided to only consider when using equipment that reliably handles such setup.
The issue with bi-amping or tri-amping, the elephant in the room, is that getting proper crossover integration is challenging enough when dealing with only a subwoofer. Adding bi- or tri-amp on top compounds the complexity markedly. Without a treated room and measuring equipment, bi-amping is going to add just about zero benefit and might actually sound worse just by virtue of how difficult it can be to set up.
The worst case performance scenario with passive bi-amping is that the original passive crossover implementation is preserved, keeping the consumer out of trouble. In that respect, the practice of giving consumers a false choice between mono amp and bi-amp that amounts to only bi-wiring with both amps driving identical signal and not getting any headroom benefit might be a sort of kindness. IMO that is better than giving consumers active bi-amp and letting them flounder in their ignorance of how to properly integrate a crossover, especially without any measuring equipment to confirm their setup is optimized let alone any expertise to rationally evaluate the tradeoffs. Those with the expertise will just sidestep around passive bi-amping entirely so it really does no harm at all and maybe some good by satiating the curiosity of those without the expertise to do active bi-amping anyway.