[Amps] 3CX1500A7 versus 3CPX1500A7

Robert Morris robrk at nidhog.net
Sun Feb 9 11:36:27 EST 2014

Do you know what the voltage at the pins measure now? 

Unless you have a variac in line, I bet it's not 5.000.

Most of the old transformers in my junk box are 115v.

My line voltage, as we speak is 121 and has been know to go to 124.

Calls to the power company, in summer, when they are fighting all the air conditioning and it goes to 127 and all my UPS's start yelling.

A 100 watt Variac or Powerstat and a meter calibrated at the pins, fixes both issues.


On Feb 7, 2014, at 12:13 PM, Larry Critchfield wrote:

Hi John,
Do I have to worry about the .5 volt filament voltage for the 3CPX ??
I do not want to modify my amp for 5.5 and then have to switch back
to use my 8877's plus the cost of new parts.
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