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Variac for 100v tube preamp questions

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I purchased a vintage 100v Japanese tube preamp and after weighing the options(voltage converter, bucking transformer, variac), i decided with a vintage General Radio W10MT3A variac/variable transformer. Assuming the variac works, i am wondering if i can use it connected to my Isolation transformer that is able to connect 600va max.  The variac allows 10amp and 2 amp selection.  How does this translate to power usage to know if my Isolation Transformer can handle it along with my 50wpc McIntosh MC250, and a tube dac, and a 50watt vintage subwoofer all connected to the same isolation transformer? 

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Look at the rear labels for all of the pieces and add up the max VA or max watts.  Watts = Volts x Amps.  So, your xfmr's 600 VA rating is essentially 600 watts (OK, not quite because the voltage sine wave is/can be out of sync with the current wave.)  Leave some room for start up in-rush current and turn on one thing at a time.  I think you'll be close to max capacity. 


FYI, fuses will pass 2x their rating for a short time before opening and maybe oversized.  They are primarily for fire protection, thus not a good measure of load or capacity. 

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