mesherm wrote:I used a trick like that until a fellow pointed out that you don't want stiff voltage there... if the line voltage goes up or down, you want the bias to do the same and "track" the fluctualtions.
In my ST-70 days I retrofitted at lest two ST-70s with CC Chong cap boards. Those boards used a Zener diode to regulate the bias voltage to -56 volts. If what you are saying is right then there are a lot of people with CC Chong modded units with problems
If their line fluctuates, yes, bigtime. The ST-70 is the hottest biased, non-auto-bias-correcting amp I've encountered so far... even all the guitar amps I work on are rarely over 80% Pa. The 50mA per tube will take a stock ST-70 to 96% Pa of an EL34 with an original 117V mains transformer.
Luckily, most areas of North America, Europe and Japan don't have this issue. My line is 126V solid with a mid-heatwave dip of 123.5V when all the A/C's are blowing snow to make us Canucks feel at home
Cheers!