Matchless DC30 power scaling

[soma_hero]

Structo, just a normal Alpha 1/2 watt.

Yngve, tubes have different operating conditions at different voltages. The reason VVR works so well on a Trainwreck type amp is because the amp is designed so that the Preamp, PI, and Power section overdrive in a specific order. By scaling voltages to all at the same time, you roughly preserve that order and just reduce output.

In something like a Dumble where overdrive mostly comes from the preamp, reducing voltage might have a bigger effect on the overdrive sound. Look at the data sheet charts. By reducing voltage you are reducing current draw and also amplification factor.

Perhaps in the DC30 (not too familiar) the overdrive is more power tube based. Try inserting the VVR after the plate/screen taps, just to the PI and preamp. Maybe it's the other way around, and you need to scale the power section and leave the preamp at full voltage?

Plenty of things to play around with

[Yngve]

I think if I were to move the VVR again it would be to scale the power section and leave the preamp at full voltage. But then I would need to install a PPIMV, which translates to reinstalling the master volume circuit I removed (I guess). Maybe I can try first without reinstalling the master volume. Would this hurt the power section in some form?

[soma_hero]

What will happen is your full-voltage preamp will quickly overdrive your low voltage poweramp. Since the poweramp is running so low it can get saturated quickly. I don't know if any physical damage will happen to components, but you won't get the same sound as you turn down the volume. You'll have to adjust the gain along with the volume..

[Yngve]

I would like to hear how bcmatt installed VVR on his DC30-clone or if Dana has some experience with VVR on DC30, but I haven't seen them here in a while.