What’s the Right Power Amp Ratio For Bi-Amping?

Al, thanks for your insight. As always it gets the mind looking at different angles. The theory I’m going on with significant differences in power requirements is that low frequencies have longer wavelengths and the woofer cone has a much larger  surface area driven to much greater excursions. The effect is moving significantly greater volumes of air. I theorize that the power to drive a 10” woofer over an excursion of 0.5” must be an order or two of magnitude greater than the power to drive a 3/4” soft dome tweeter 1/100”. 

Hi all, Here's something to think about. If you have two identical amps you will have the option to vertically bi-amp as well as horizontally as you guy's are discussing. I don't know the advantages of each way, maybe ALMARG will chime in.Tish

Sleepwalker.....I was giving good advice to all who read these pages.

Racamuti makes a good point. If identical amps are used a vertical configuration (one amp per speaker, one channel powering the lows and the other channel powering the highs) is considered to be preferable to a horizontal configuration (one amp for the lows of both speakers, the other amp for the highs of both speakers).

One advantage of a vertical configuration is minimization of sonic effects that may result from inter-channel crosstalk within each amp, since both channels would be processing the same signal. Another advantage is that a vertical configuration would typically allow the amps to be positioned closer to the speakers, making it possible to use shorter speaker cables, potentially reducing both their sonic effects and their cost.

Also, of course, using identical amps eliminates the possibility of loss of coherence that might result if the two amps have differing sonic characters.

Regards,
-- Al

As Al points out, it doesn’t work that way.

While the speaker crossover will reduce the current, the amp will still produce the full spectrum voltage, minimizing overhead.

If you are passionate about doing this though, there may be a tweak. IF and only IF all three conditions apply:

• Bi amping a 2 way
  
• There is a resistor in series with the tweeter
• This resistor is first then you can short it, and reduce the tweeter amp volume.

If you are bi-amping a 3-way however, or that resistor comes after a cap or coil, this won’t work.

This will allow your tweeter amp to produce less output, and eliminate wasted heat in that padding resistor.