65 amps master voltage?

[imaradiostar]

Anyone know what is different about this circuit compared to the output power scaling schemes out there?

jamie

[Alex/Tubewonder]

These two and others are marketing names for a variable voltage regulator straight from textbooks. One of them uses a Master/Slave scheme to simultaneously adjust high voltage and idle current (bias) of output power tubes.

[imaradiostar]

So they're cranking up the current as they reduce the plate voltage?

Does this mean they're leaving the preamp alone and running it at max voltage?

Is the phase inverter scaled?

jamie

[Alex/Tubewonder]

Yes, they're trying to maintain around 70% (magic number for some) of max plate dissipation for as long as possible as plate and screen grid voltages go down. This of course is not possible very far down.
Personally I see no point in reducing preamp or PI supply voltage. But as they say, one mans perversion is anothers prfection.

[imaradiostar]

I figured as much. I wonder how well that works? I played a scaled amp once and wasn't impressed but people seem to love 65 amps in the reviews and videos I've seen. Interesting stuff. Thanks for the info!

jamie

[mullardel34]

fender 75

I figured as much. I wonder how well that works? I played a scaled amp once and wasn't impressed but people seem to love 65 amps in the reviews and videos I've seen. Interesting stuff. Thanks for the info!

jamie

Check out Fender 75 circuit-They did it years ago