Details for bi-amping

Well, now I'M confused, by your summary.

So you plan to biamp passively with 4 identical tubed monoamps?

Two STRONG advantages are that the gains will be identical and that you'll have 3dB more power. Another advantage will be slightly less IM and harmonic distortion.

Good luck.

One advantage not yet mentioned is that if your speakers split the frequencies between bass (NOT including midrange) and MR/treble, you can use a high-gage-but-inexpensive cable on the bass. If your speakers split the frequencies into bass/MR and treble--2-ways do this--I recommend equally-high-quality cable on both legs.
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Jeff,
crossover point of 'stock' speakers is still unknown.

Just for example, my 2-way panels split at 600hz.....

And indeed, Nik, the cost / benefit is really up for grabs. To be factored in is the cost of you time (therapy would be cheaper) to tune your proposed setup in. You may even have to resport to measurements.

Magfan is right. If you're dealing with a 2-way with a 2K crossover we could have saved a lot of time and called you nuts to begin with. On the other hand, if you're talking about an Infinity Kappa9, that's another kettle of fish.

Some more thoughts/issues.

Yes, you do need to match gain; IMHO, the amps don't need to be of equal power but should be in the ballpark; and I would not use any Y-cable from a preamp.

Most people using a bi-amp setup will use an active crossover between the pre-amp and the 2 pairs of monoblock power amps (a la Pass Labs XVR1). This is so that each pair of monoblocks will be dedicated only to amplify a certain portion of the audio band - either the low freq's for the woofers or the mid/high freq's for the midrange/tweeters.

Contrastingly, if you bi-amp with a passive crossover (e.g., use the crossovers built into the speakers), then each pair of monoblocks will amplify the full audio band. For example, the monoblocks for the woofer will be amplifying the full audio band but at the passive crossover, the mid/high freq's will be filtered out and essentially lost (the same thing happens for the monoblocks for the midrange/tweeter, except that the low freq's. will be filtered out and essentially lost).

Passive is not very efficient. Active is more efficient because only the specific part of the audio band is being amplified. This latter method leads to what, to me, appears to be more headroom - that is bi-amping my 100W Aleph 2 monos and my 125W Threshold SA/6e monos sounds much more than `100W full bandwidth.

So, let's say you now want to use an active crossover. In doing that, you also need to remove the passive crossover from the signal path. Otherwise the signal will be going through 2 filtering networks - first the active and then the passive crossover. This should be a consideration if you ever want to sell your speakers. In some speakers, removal of the passive crossover can be reversible; others not.

Also note that a few passive crossovers not only filter the lows/mids/highs, but also act as an rudimentary equalizer. If you go the active crossover route, you will lose the equalization that was inherent in the passive crossover. Might be better, worse, the same, or just different.

Also, someone mentioned using XLRs and RCAs for the 2 pairs of monoblocks. You don't have that problem with an active crossover because it will split the signal from the pre-amp. Also, if you do use the XLRs and RCAs from the pre-amp, note that there usually will be a gain difference from these outputs from a fully differentially balanced pre-amp.

In sum, a lot of things really need to be looked into. But if you can get it set up correctly, the bi-amped active crossover method works real well.

FWIW, from time to time, I bi-amp with an active crossover my Aleph 2 (for mid/highs) and Threshold SA/6e (lows). When set up right, they sound amazing - the liquidity of the Alephs on top with the bass authority of the Thresholds.

Also, be forewarned, if you like to setup your system once and not touch it, the bi-amp & active crossover may not be for you. The level of adjustment and permutations available with such a set up leads to constant fiddling. =) Some like it, some don't.

YMMV

"Contrastingly, if you bi-amp (SIC) with a passive crossover (e.g., use the crossovers built into the speakers), then each pair of monoblocks will amplify the full audio band. For example, the monoblocks for the woofer will be amplifying the full audio band but at the passive crossover, the mid/high freq's will be filtered out and essentially lost (the same thing happens for the monoblocks for the midrange/tweeter, except that the low freq's. will be filtered out and essentially lost)."

A common misconception. Yes, the entire frequency band is presented to each poweramp, but the 2 ends of the frequency band are NOT amplified equally, because the crossover presents a rapidly rising impedance within the filter (rolled-off) band. That's why one 'saves' amp power when passively biamping.
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