In Reply to: A new but improved hum posted by airtime on January 1, 2022 at 14:36:04:
Voltage across R19 and R21 --- 109v across and all four at 250vdc at plates
R5 bypassed --- music does pass undistorted. low hum both channels with Left a little worse.
Bypass R9 with 100uf cap --- Hum worse in LEFT then drops very low. Hum is still present in the RIGHT but very low. Music passes well
Bypass cap C13/15 to grd leg of R5 --- Hum starts real loud on LEFT then fades. Both have low hum with the LEFT a bit louder.
Disconnect NFB --- Hum starts real loud on the LEFT and fades with low hum in both channels. Music passes well.
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Follow Ups
- Test results for Trobbins and Triode K - airtime 15:46:01 01/04/22 (2)
- Now this is weird - airtime 16:38:43 01/04/22 (1)
- RE: Now this is weird - Paul Joppa 20:05:41 01/04/22 (0)