It's been a while I didn't get a soldering iron hot but I received this morning the parts needed for my next project and it feels nice. Good feelings have to be shared
Nothing fancy here, it's kind of an opportunity build, based more on what I've got on hand than careful planning. A yamaha integrated just died and it offers me a 36-0-36 xformer (+a weak extra 17v winding), a big convenient heatsink, connectors and a nice case. Here's the plan:
The pseudo regs provide decent ripple reduction (accurate voltage values aren't very important here) and a slow start.
R7 stands for the 12au7 heaters, r2-r9 are a 500k trimmer to set the output voltage at exactly 12.6v and the small transistors might be bc560c or bc337-40 depending on what I find in my boxes. The input stage runs at 3ma per tube or so and the plates sit at about 75v (is there somewhere a study of how different bias for the sohaII input stage sound ?). I might need to add a relay to avoid thumps at startup, I'll see.
I'll work on it tomorrow and during the week-end. Hopefully, I'll tell you how it ended on Sunday night. Till then, if anyone spots a mistake in there, it might save me some headaches ;)
Power supply done and working properly. I added a pair 0.33r resistors in between the diodes and the first cap of the main power supply, to smooth things a bit (it limits spikes in diodes). Nothing fancy in terms of parts but solid BC and rubycon caps all around. The ugly duck:
Edited by 00940 - 2/24/13 at 7:48am