The Amp Garage

Decent rule of thumb for tube rectified supplies. The one-step-finer rule is 1.4 * AC minus the rectifier drop and any resistive losses in the transformer. Sorry R.G. but no, I use that rule of thumb for diode rectifiers. Valve recto is even lower. The factor you have missed is the first cap ripple...

We say diode rectified gives 1.4x AC voltage as the DC, but this is unloaded. My rule of thumb for valve amps incorporating the first filter cap ripple has always been 1.32x. 330 x 1.32 = 436VDC so in my books you're spot on where it should be.

I originally put in a Vox style Cut Control on my Marshall 18 Watt style build. Very different amp to yours but I also found it to be pretty useless. Not much later it was ripped out and the front panel hole used for a VVR pot.

For me usually electrical tape (because I've got it on hand and it's soft) folded over on itself.

Thanks. Floating the heater supply at half the 170V B+ was inside the submini valve cathode to heater voltage spec and meant I could get B+ and heaters from a single 0-30V transformer.

Keep us posted with your build!

I had a client that wanted a jazz amp as a single channel version of the Gibson GA-75 with some specific extras (switchable preamp stage local NFB, effects loop, bright and treble bleed). It turned out very nice for finger style jazz playing.

I bought a number of 6J32P a while back when everyone was buying $2 Russki valves. They've been great in my 18 Watt with EF86 channel, reliable and not microphonic.

Guts and size comparison.

And some pics. 16 years ago, I still have the amp and it sounds great.

Here are the final schematics including PI/PA VVR.

Through some breadboarding, I found a 220k plate resistor gave me the most gain out of a 6112 preamp stage. Anything bigger and gain dropped off again despite what the plate curves said in theory. Then I tested bias point between grid clipping and cutoff and got the following values of cathode resis...

I also socketed them. Soldered the submini into a DIP-8 machined pin socket. I made a PCB for my amp, so it also has DIP-8 machined pin sockets for the valve locations. Then the submini socket plugs into the PCB mounted socket matching orientation marker. My submini build was 16 years ago. I'll dig ...

I went through this with my submini version of an 18 Watt Superlite TMB. Started doing what everyone else had done, just dropping a 6112 into the existing circuit values as you say. What I found lined up with the plate curves on the datasheet - noticeable lower sensitivity (and therefore gain) than ...

Mason's clips sound heavier than Brian's and John's and obviously all three preamp versions are different, but I don't know if it's also just his playing style and guitar that makes it sound like that. Brian's blues clip is all EVH blues riff but doesn't mean his amp wouldn't chug like a monster wit...

The obvious gap in my "keeper" flock is a good brutal metal amp for the Drop B stuff I seem to be playing more of these days. At the moment I've broken out the old Zoom G2 modeller but over time I'm noticing something about it that's starting to grate on me. I do have an almost finished Upper Decker...