Quote:
Originally Posted by metropolis74
Might just be the nature of the single-ended beast.
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No, it isn't.
I've built a ton of these and I've managed to eliminate the hum. Mine are dead quiet. They're also aggressively obnoxiously gainy (as gainy as an amp with three tubes can be) and I've mangaed to elminate the noisy artifacts you might expect. I use carbon comps everywhere aside from the dropping string.
Quote:
Originally Posted by stax
One switches in a treble bleed cap on the volume pot, the next is negative feedback on or off and the third switches in a 25uf cathode cap that’s in the 5E1 but not the 5F1.
Stax
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I'd like ot see a gut shot of that thing.
I build mine on repro 5F1 chassis. On the minus side it's tight in there. On the plus side it's tight in there, that keeps the signal path short. That's one of my Rules to Live By... keep it short and sweet. Figure out what it has to be and hardwire it. Excess wire is just a bunch of little antennas (antennae?!
) and the excess wire can pick up hum. Keep the signal path short, keep the ground path short then use shielding sparingly to eliminate any residual hum and crosstalk.
Check your filament voltage. Should ideally be 6.3. The more you increase filament voltage above 6.3 volts the more the amp will hum. I like to keep my filaments at around 3 volts on either side of ground. DC filaments increase parts count and they're unnecessary.