Details for bi-amping

The amount of relative power of amps used in a biamp setup is very much related to the crossover point.
Take a crossover of 10khz. How much power, as a %age of total does music contain above the crossover? Maybe 10% or 15%?
Likewise, if you crossed over at 100hz, you may need MORE power to the mid/hi amp than the bass amp. Above crossover may end up as 80% of total power needed.
Depending on crossover point, it may actually be appropriate to mate a relatively small amp on 'top' with a more powerful amp for the lows....

3 way designs would just complicate the heck out of it!
As an example:: The Braun Tri-Amp.....maybe early late '70s / early '80s? had three amps per speaker. 55watts=bass 35watts=mids 15watts=highs. Wacky expensive for me at the time, I looked but didn't touch!

The OTHER issue I never see addressed is what I call latency. How long does it take a signal to get thru amp 'a' vs amp 'b'? What is the effect at crossover if one amp is a hi feedback design (for bass=hi df) vs an amp with less feedback used above crossover? How will those distortion products interact at crossover +- 1 octave?

Excellent points, Magfan. To further clarify my point about power, though, what I was basically saying is that for passive biamping voltage swing capability needs to be considered as well as power capability, particularly if there is a large disparity in the power capability of the two amps.

Using your extreme hypothetical example of a 10kHz crossover, the amount of power that would have to be provided by the high frequency amp is extremely small. However, if say a 50W amp were used for the highs and a 500W amp were used for the lows, the 500W amp would in effect be no more powerful than, for example, perhaps 75 or 100W. Asking it to provide more power than that would cause the OTHER amp to clip, resulting in lots of extraneous non-musical high frequency energy going into the tweeter.

Good point about latency, aka propagation delay. You're right, that never seems to be addressed. Not sure how it would play out quantitatively under typical circumstances.

Best regards,
-- Al

If you are planning on passive crossovers, then unless the amps are identical, you will have gaps or mismatch is high/low output of the amp/speaker setup. Some speakers (Martin Logan's for instance) have switches that allow you to adjust the input of the amps to the speakers for just such an occurance.

However, it appears to me that if you want to bi-amp, then you can;
1) get identical amps for high/low inputs

2. Get an active crossover which allows you to adjust the levels of the amps.

There are some very good active crossovers out there and even your speaker manufacturer may have or suggest an active crossover for you also.

enjoy

Have we noticed that Nikmilkov hasn't posted a word since the original message? Probably he's so confused and discouraged from our audiobabble that he'll either never try passive biamping or never ask a question here again! :-)

Nik, the biggest and IMO-only-important issue is gain matching the 2 different amps. Resolve that and you're well on your way.

And DO NOT--DO NOT--DO NOT combine passive biamping with an electronic crosover; ONE crossover network per speaker is just the right number.
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Plan 'b' would of course be to can the biamp idea and get a single amp per speaker of high enough capability to render biamping unnecessary.

Maybe something like the Spectron offering? Or the kilowatt Pass amp?

Put any extra funds into a whole house lightning / surge protector, dedicated circuits to the amps and listening area and top it off with the appropriate room treatments and a couple 'o subs.

Back to the OP.
Before you even start choosing amps, I'd get the preamp thing sorted out. Some preamps have balanced AND single ended outputs which may allow use of both...simultaniously.
I'd like some additional information.
Where (frequency) is the proposed crossover? Are the speakers 2-way or more than 2-way?

Synergy will be critical and as others have pointed out, may be difficult to pull the trigger on.