[sdiy] outlet as variac? calling all EEs...

[sasami at blaze.net.au]

The reason a Variac is used to bring up a tube amp is that 
the filter capacitors may need reforming. If they DO need 
reforming, they present themselves as a low value 'resistor' 
across the output of the transformer. This overloads the 
transformer and cooks it.

Variacs are not needed if - the capacitors are already 
healthy or - the transformer is capable of running into a 
heavy load without damaging itself (i.e. over rated to 
buggery)

Ken


>
>> But in any case, can it be a good thing to run ANY 
>> electronics at a voltage
>> other
>> than the designed voltage? ANYTHING could happen with 
biassing.
>> I wouldn't dream of putting a variac on an amp,except for 
a 
>> minute or so.
>
>okay, so this is interesting.  word on the street is, leo 
fender never did
>the variac tango either.  so what's the point then?  is it 
really necessary?
>
>alex