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Killing hum in DIY Twin-Amp

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2/25/2000 12:51 PM

Keith

Killing hum in DIY Twin-Amp I'm encountering an annoying 60Hz hum in my project amp (5F8a). It disappears when I pull the cathode follower, but pulling the first preamp tube has no effect. I'm using star grounding, and have adjusted my lead dress several times. I don't think it's the heaters, because this problem cropped up rather recently. Overall tone in the amp is great otherwise. Can anyone shoot some ideas my way? Thanks!     Keith

 

2/25/2000 1:42 PM
J Fletcher	Bad tube? That would be my 1st guess, but you've probably tried a different one already....Jerry

 

2/25/2000 2:43 PM
Keith	Yeah, I've swapped numerous times, to no avail... I'm going to scope the circuit to see exactly where the hum is injected.

 

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