Bi-amping Rules

While anecdotal indications are that there are certainly **some** cases where audiophiles have achieved fine results by bi-amping, in both passive and active configurations and by using different as well as identical amplifiers, I agree with the foregoing comments and the article that in the great majority of circumstances the corresponding funds are likely to be applied more constructively in other ways. And presumably and hopefully the designers of most high quality speakers have gone to great pains to try to make them sound as coherent as possible throughout the frequency range. Why risk undoing that by using different sounding amps?

Also, while I agree with most of what is said in the referenced article, I don’t quite agree with the following paragraph:

Ok, so what about just using two amplifiers and forgetting about the electronic crossover? Simply using two amplifiers is not true bi-amping and does not offer the same advantages; we still face the limitations of the passive crossover. What about the notion that bi-amping reduces stress on the amplifiers since they are powering only limited frequency ranges? That would be true in a true bi-amp configuration where the frequencies are split ahead of the amplifiers, but in a passive environment both amplifiers receive a full range signal from the preamp and dump that power into the speakers, regardless of whether one is connected to the tweeter or woofer inputs. The only benefit (and it marginal at best) is simply the additional power offered by the second amp.*
* There may be a bit more advantage obtained when one employs two identical amplifiers, one for each speaker – vertical bi-amping.

Passive biamping will in fact relieve the bass amplifier of having to deliver current and power above the frequency at which the low pass section of the speaker’s crossover has essentially completed its rolloff, and will relieve the mid/hi frequency amplifier of having to deliver current and power below the frequency at which the high pass section of the speaker’s crossover has essentially completed its rolloff.

HOWEVER, when it comes to passive bi-amping what seems to often not be realized is that since both amps have to output VOLTAGES corresponding to the full frequency range of the signal, using a very powerful solid state amp for the lows and a much lower powered tube amp for the mids/highs (as some audiophiles do) will probably result in much of the power capability of the higher powered amp being unusable. A much lower powered amp can be expected to generally have a much lower maximum output voltage capability than a much higher powered amp, which in a passive bi-amp arrangement (i.e., without a crossover "ahead" of the amps) means that how much of the power capability of the higher powered amp is usable will be limited by the clipping point (the maximum voltage capability) of the lower powered amp.

Good luck. Regards,
-- Al

Unless you have the exact model for both amps, don't bother.  If you're contemplating a purchase of 2 like amps...getting 1 good amp for a side  is better than 2 lesser ones...and certainly better than different models.

I passively Bi amp my Maggie 3.6's with a pair of David Berning ZH270 power amps. The result is much better sound from my  Maggies then using one amp. In fact I won't get 3.7's because with there series crossover you can't bi amp. I also when I was upgrating one of my bernings I thru a vtl ST80 in to replace one berning and it sounded just as good. One nice things about the Berning amps is they have volume controls so I can adjust bass/mid levels versus the treble level. 
Alan

Thanks for all the inputs. I have experimented bi-amping my Aerius i  using few different amps, all SS, and could never get it to sound right or better than a single (good) amp.

Kalali, my dealer recommended a pair of Aesthetix Atlas stereo amp for vertical bi-amping.  It's a hybrid amp with a built in crossover. 

I am working on a plan to try them out in next month or so.