Bridge rectifier vs. two-diode rectifier?????????

[vmazz]

Thanks Enzo. Is there any advantage to putting the bias tap before or after the standby? Some era marshalls have it after the standby, so that when switched to standby you have no plate, screen or bias voltages to the tubes.

[g1]

For safest operation, the bias should always be taken before the standby.
Any of the old marshalls that do not provide bias when in standby mode should be corrected.

[vmazz]

Thanks for the heads up G1. Can you explain why? I mean is it a safety issue for the user, or a better design for the life of the tubes? Thanks again.

[g1]

Better for the tubes. The bias takes a finite amount of time to charge up. You don't want the tubes getting plate voltage before the bias voltage comes up, they will conduct high current.

[The Dude]

I'll add: Having the bias supply post standby is also harder on power supply components. There is enough surge current as is when bringing an amp out of standby. If bias isn't there already, it adds even more surge current to the equation. Standby is only there to keep the output tubes from conducting. We don't need to remove the bias voltage to accomplish that.

[vmazz]

Great input guys! THanks! A lot of this stuff I assume is the case, but it really helps to have those with the experience and education to explain it to me, for a more in depth understanding.