Axiom Home Page Forums General Discussion Technical Questions For biamping M60s, crossover need to be removed?

Here's what happens when a receiver with one power supply is set to bi-amp:

It's single pool of power is now flowing from two sets of outputs. This alone isn't bad. Some amp designs use multiple output devices on a single channel for better power handling.

BUT, those amps are designed to run bridged together, which requires some planning in the circuit design. When two separate outputs are activated with the same signal, but are not designed to be bridged they cannot be connected together (or Bad Things™ will happen).

So the bus bars have to be removed from the speaker. Now you're dividing the available power between two outputs. Again, not so bad N / 2 * 2 still equals N. Though that only applies if you can use the full power from each output.

When powering a full range speaker, that has no ultra- or infra- sonic filters (like most speakers), most of the current no matter it's alternating frequency can find a way through the system. The crossover will route some through the tweeter, mid, or woofer, but it follows its path of least resistance and winds it way through.

But when you cut a speaker in half, and have two separate systems, one which can only pass highs, and one which can only pass lows, much of the electrical energy will be turned to heat in the crossover network because there's no path for it.

So instead of having (N / 2) * 2 usable power, you end up with (N / 2) / 2 * 2. Or N / 2, meaning you've lost half of the usable power to heat. Those number are really rough examples, but the principle is true. Dividing the power across multiple outputs, and then not being able to use that full output because crossover network blocks it causes the receiver to have less available for output than running one output into a full-range speaker system.

Great explanation Chris.

He's such a showoff!