waldo041 wrote:The Autoformers in the mac when in mono mode are also in parallel, so their math is the same as the speakers you are using. If you have two 8 ohm speakers in parallel they need a 4 ohm likewise with mono operation the Autoformers are in parallel so the 16 ohm taps become 8 ohm taps, the 8 ohm taps become 4 ohm taps and the 4 ohm taps become 2 ohm taps. So with speakers paralleled for a 4 ohm rating the ideal taps to use in Mono are the 8ohm taps bridged together.
I personally would run the amp in stereo mode and get a y cable to combine the preamps output to 2 signals into the mac. then run each speaker on it's own channel(left and right).
I only have a single input on my cab that connects to both 8ohm speakers in parallel. That, and considering how many shows I play - constantly setting up and breaking down, and lugging my gear around - it's worth it to me to simplify, and keep the cab as it is with the 1 cable connecting to both my speakers, rather than rewiring everything and using 2 cables, 2 inputs, 2 volume knobs, etc.
With that said, in mono mode for my two 8ohm speakers in parallel, I would bridge the 8ohm connectors together, the com connectors together, then connect my speaker tap to 8ohm and com?
(Let me apologize ahead of time, I wish I understood this stuff better... =P )