Good to know.  I may try using a single high-voltage transformer for a mains supply and using a buck to produce the filament supply in a future build.  I'm not sure that it will really be any more space-, power-, or cost-efficient, but it would be an interesting exercise.

Thanks!  One transformer is for the 6.3v heater supply and the other is for the plate/collector supply (around 70V).  When I build my full-size stereo (2 projects away) I'll be doing a dual mono supply, but for this little experimental project I thought I'd keep it simple.  I may be able to...

Yeah, the case could be a much better shield, but unless it gives me problems I'm okay with it.  Of course I have to cut plastic isolation gaskets, which is annoying, but such is life.   I haven't actually had a chance to compare it to any other amps yet, other than to verify that yes, it...

Here's a few shots of my most recent build.  There's a bit of work to be done yet (ground isolating mostly, though there will be some interesting LED lighting of the tube that I'll be showing off later as well ;) ).  This is the first audio amp I've designed and built completely from scratch...

Out of curiosity, what did you use to affix your boards to the chassis?  Is that some sort of epoxy or putty?  If it works well that would be more convenient than drilling standoff holes.  (specifically I'm looking at the vertical board on the top-right of the chassis in the picture)

Wow, I love the lighting!  I'll assume it sounds as good as it looks and say nice job!

Here's my first (and last for a while) recable job.  A while back I put a pair of KSC75s through the wash and destroyed one of the drivers.  Turns out my best friend and bandmate is deaf in one ear. So, for fun, I wired up this little "KSC75 Monophone" out of the remaining good driver.  There's...

Indeed I did ;)

Here's on option that isn't necessarily a great idea, but was fun to illustrate:     Pros: -makes for easy swapping -solid connection -fun illustration   Cons: -kind of clunky -will probably introduce extra capacitance -plenty of opportunities for soldering errors to...

I thought I'd pipe in, mostly since I love lighting my projects, and love seeing LED-lit projects.  If you're curious how to select a bias resistor for the LEDs, here's the method I use:   A)  Select your LED. B)  Locate a datasheet for your LED. C)  Choose an LED current            ...

I have one of those as well.  Cheap little buggers ($12 maybe), but they get the job done very well.

You can bias a PNP the same way you'd bias an NPN.  Here's the hybrid pi model of a PNP:       Note that the PNP is drawn "upside down", with the emitter (E) at the top and the collector (C) at the bottom.  You'll bias it the same way you would an NPN, except that the emitter will be...

I'm looking at your layout here: https://lh4.googleusercontent.com/-qE7XzkVTjsI/T0O4wRY_enI/AAAAAAAAAF4/icJYQ7ZiqUs/s1600/ssmh.jpg   Are you using IRF510s for the MOSFETs?  Because if so, I think the pinout is different than what is shown on your layout.  Looks like the gate is on the far...

I always wondered at the feasibility of using a single transformer and a boost converter for the high voltage.  I know the purists tend to frown on switching regulators for audio amps, but if you design them right they tend to have very little ripple.  Plus, if you switch fast enough - say 1MHz...

Thanks Kevin.  I figured it must be something like that.  Those dual triodes are nearly indestructible.  Well, if you run them overcurrent they tend to ... blacken ... somewhat, but you know what I mean.  Destroyed a nice pair of 12AU7s that way.  I'm guessing low-power pentodes like EL84s and...