Gary, glad to know that you are well now. One of the risks of this hobby is back injury due carrying all these heavy amps around. Just be more careful in future. I've had my fair share of back problems due to moving amps around.
On another note, I've read that running amps in mono mode doubles the wattage but halves the current delivery. Is it true? If that is so, wouldn't biamping be better (vertically or horizontally)?
Yeah - I keep saying that I'll make lighter gear. When I went to class D for the Genesis Reference amps, I thought that was the solution. Before them, my amps were tube, and with two humongous transformers (power supply and output), the monoblocks weighed nearly 40lbs each. Well, I managed to make nice, light amps..... unfortunately the power supplies weighed 40lbs each. *sigh!*
When you run solid-state amps in mono mode, what you are doing is reversing the phase on one channel, and running both channels in anti-phase. This means that the maximum swing voltage is effectively doubled. Since power = voltage squared times resistance (P = V^2 * R) and each channel still delivers the same voltage both channels in anti-phase delivers twice the voltage and you get effectively 4 times the power into the same load.
To get 100W into 8 ohms, you need an amplifier with a voltage capability of about 28 V. So, if you bridge them and deliver 56 V, you effectively get 4 times the power. Since I = V/R you also get twice the current.
That's the simple answer..... assuming perfect power supplies. Unfortunately, the damping factor is also affected as damping is simply load impedance divided by source impedance. For example, if the speaker is 8 ohm and the output impedance of the amplifier is 0.01 ohm, then you have a damping factor of 800. Two channels of the amplifier in series will add the two output impedance together, and that bridging will result in halving the damping factor (not good). However, if the two channels of the amplifier share the same power supply, having two channels in anti-phase almost doubles the effectiveness of the power supply since most of the power draw is in the bass, and bass is almost always mono (especially if the source is vinyl).
With tube amps, you have the possibility of paralleling the channels, instead of bridging. This results in the same potential voltage swing, so no increase in power, but you get a halving of output impedance (two output transformers in parallel) and hence a doubling of damping factor.
