No, You Cannot Bi-Amp

Some good points have been made above. With respect to passive biamping, another commonly overlooked point is that in that arrangement both the high frequency amp and the low frequency amp have to output the voltage range of the full range signal. Which means that if a low powered tube amp is used for the highs and a much higher powered solid state amp is used for the lows, most of the power capability of the solid state amp will be unusable and wasted, because the maximum volume setting that can be utilized will be limited by the clipping point of the low powered amp. Also, of course, gain matching is likely to be an issue in that situation.

Regards,
-- Al

Relative power needed is almost entirely governed by crossover point.

If you crossed over at 10khz, you could make due with a 30 watt tube amp on top of a 300 watt SS.

Than, other issues would come to the fore.

01-20-12: Magfan
Relative power needed is almost entirely governed by crossover point.
If you crossed over at 10khz, you could make due with a 30 watt tube amp on top of a 300 watt SS. Than, other issues would come to the fore.

Right! A major "other issue," if the two amps are being used in a passive biamp arrangement (i.e., without an active crossover ahead of the power amps) being that some number approaching 270 watts of the 300 watt capability of the SS amp could not be utilized, without clipping the 30W amp. Essentially the 300 watt amp would be reduced to not much more than a 30 watt amp in that scenario (the exact value depending on the voltage swing capability of the 30 watt amp). Which was exactly my point.

Best regards,
-- Al

01-20-12: Magfan
Relative power needed is almost entirely governed by crossover point.

If you crossed over at 10khz, you could make due with a 30 watt tube amp on top of a 300 watt SS.

Than, other issues would come to the fore.

Right! A major "other issue," if the two amps are being used in a passive biamp arrangement (i.e., without an active crossover ahead of the power amps) being that some number approaching 270 watts of the 300 watt capability of the SS amp could not be utilized, without clipping the 30W amp. Essentially the 300 watt amp would be reduced to not much more than a 30 watt amp in that scenario (the exact value depending on the voltage swing capability of the 30 watt amp). Which was exactly my point.

Best regards,
-- Al

if you are going to use the in-cabinet speaker x-overs as-is then the best way to do passive biamping is the method done by member 'jefferybehr' - he's used 4 identical amps that are driven by his preamp. Take a look at his system pix.

I'm sorry, but the power relative power needed IS governed by the crossover frequency. At least for music with a 'normal' distribution of frequencies.

With the crossover at 10khz, per my example, you really would need more than 90% of the power below crossover, with only 10% above.

http://sound.westhost.com/bi-amp.htm

The 50:50 point is about 350hz. I don't know that active or passive makes much of a difference. The amp will only have to produce power for those frequencies for which the speaker has a need.

The 'other' factors I was thinking about would be amp latency. How long it takes a siganl to pass thru the amp.
Also, gain and how linear the gain is will play a part in freq. balance thruout the volume range.