Supreme (Garnet) Amp

[Helmholtz]

Power supply ripple is 120Hz, so filter caps won't help 60Hz hum.

Amp uses half-wave rectification, so 60Hz ripple here.

60Hz ripple paired with SE output requires good filtering.
I would try tacking the 50µ cap in parallel with the screen node filter.

[mtlbasslad]

Power supply ripple is 120Hz, so filter caps won't help 60Hz hum.

So where do I look? And when I said 60hz hum, that is by (old) ear - not by any serious techy analysis... could have been 120hz
But should I expect this amp to be totally silent?
Power supply in this amp is the rectifier tube....

[g1]

Single ended power amp will always have more hum than a push-pull arrangement.
You can't increase the value of the cap at the rectifier tube, but you can increase the screen node cap like Helmholtz mentioned. It's the 30uF shown on the schematic. Just tack the extra one you have in parallel for a temporary test.

[mtlbasslad]

Single ended power amp will always have more hum than a push-pull arrangement.
You can't increase the value of the cap at the rectifier tube, but you can increase the screen node cap like Helmholtz mentioned. It's the 30uF shown on the schematic. Just tack the extra one you have in parallel for a temporary test.

The extra one I have is 50uF - in parallel with the 30uF to test? Or substitute the 50uF for the 30uF?

[mtlbasslad]

I did tack on extra 50uF in parallel with 30uF - no difference in hum...

[mtlbasslad]

Well, the customer thinks hum level is acceptable, even if I don't. He's taken it home.
Thanks once again for the help everyone.