"Arfa Daily"

The power supplies in guitar tube amps are universally linear. Simple
transformer, full wave rectifier, reservoir cap followed by L-C or R-C
filtering. Rails up to 500v can typically be found feeding the output
stage, and it's not at all unusual to see ripple voltages of 5 volts or
more on these high voltage rails.

** The ripple voltage on the first filter electro is typically 10% of the DC
level - at ful load.

This means up to 50V p-p for a 500V rail.


The hum on the output is barely noticeable,

** The push-pull output stage rejects supply hum almost completely - until
the amp goes into clipping.

However, it is crucial that the screen supply is hum free or the output will
be amplitude modulated at 100 Hz.

Fender made a blunder with this when they built the Super Twin.


.... Phil