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Conrad-Johnson PV-10B: Low-level Hum

24.147.214.52

Spending a bit more time with this preamp (my brother's PV-10B) to help troubleshoot issues, there's a large channel output imbalance, but there's also a low level hum.

60Hz line hum coming through the power supply?

The unit is pretty simple. There's one 4700uf 35V electrolytic capacitor in the power supply (the preamp only has two other electrolytics, both of small value, and all the other capacitors are not electrolytic). I'm hypothesizing this is a power supply issue, and related to filtering. I swapped the linestage tubes to see whether it may be a tube issue. Hum was still there.

Thoughts?

Follow Ups:

RE: Conrad-Johnson PV-10B: Low-level Hum - dericmc@live.com 11:01:50 11/08/23 (0)
That sounds like going to be your capacitors leaking, the electrolytic ones. Sometimes you can add bypass caps across the electrolytics 1 ufd or less .1 ufd are best decent brand like solen caps.
RE: Conrad-Johnson PV-10B: Low-level Hum - Triode_Kingdom 18:08:40 09/25/23 (0)
A shorted regulator or pass transistor in the power supply can also cause hum. I think you should try to determine whether it's 60Hz or 120Hz before continuing.

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