Regulated supply LFO vibrato???

[Satamax]

Huh guys am i mad??? I was thinking about tube regulated supplies, and went astray. Wouldn't it be funny to have a tube regulated supply in a tube amp, which would have an oscilator as reference, so the B+ would vary. I won't build it, that's for sure, that would be a waste of glass, but i like the idea

[R.G.]

Not too hard really.

The trick is - don't use glass.

Have a read at (GEO) on the MOSFET Heresies and the MOSFET replacement for the Fender tremolo. Alls you gots to do is
(a) set up a BFM (that's a Big Freakin' MOSFET) as a series pass device on B+. This one has to be made to pass high enough voltages and currents and to dissipate enough heat. Multi-ampere 1kV MOSFETs are available. It's probably simplest to set this up like an amplified zener between power ground and the centertap of your power transformer.
(b) set up a MOSFET as a tremolo oscillator, like in the tremolo article.
(c) feed the pass MOSFET a variable percentage of the LFO. The LFO will make BIG LFO signals, so you'll have to pad it down to the right voltage for modulating the B+, maybe 75-100V.

Notice that this does not change the bias voltage to your output tubes, so there may be side effects of intermittent crossover distortion as well. Maybe good, maybe bad. Can't tell.

[Satamax]

Thanks a lot RG! Well, i might not be that crazy then??? Huh, has it been done before? I'm seeing it with tubes thought. 6C33 Tho, you all know me by now, talk a lot, undestand a bit less and do fuck all Exept moding old BF amps Or sound cities! May be the occasional recap/repair/tube change for a customer or two! But i finaly bought some punches!

Bye.

Max.

[Steve Conner]

Hi Max,

I bet it would sound like a bias wiggler tremolo circuit. You're wiggling the plate and screen voltages instead of the bias, but I reckon the sound would be similar.