[quote name='mcnach' timestamp='1344090696' post='1759668']
This question has been asked many times (not a dig at you, I ask questions that have been asked before many times just saying that you can find this info elsewhere from other people more reputable than myself, that's all )
So, yes... find the details on the TC website.
But the short answer is: it's ok.
Impedance is not a fixed number for all frequencies, so giving one number alone is an exercise on abstraction. An indication.
TC knows the behaviour of their amps and of the speaker cabs they use with those amps, so they recommend to treat their "8 ohm" cabs as "8 ohm" cabs when using other amps, but if using TC amps, you can use up to three of them.
The amp has a auto-shut down safety mechanism built in, so it's unlikely you'd damage it if you went lower than you should, but yes, 3 TC cabs are ok with TC amps. In fact it was one of their advertising points: "use up to three (TC) cabs for a ridiculously powerful rig", or something along those lines.
Mixing brands? Treat the head as a minimum 4ohm and cabs as rated in the back.
All TC? Then use the head with up to three "8ohm" cabs
[/quote]
Very helpful, Thanks