LM4780 Hum.

[ethermion]

I built a pair of LM4780s for a friend of mine. They are from www.chipamp.com. They sounded fine at my house, but I did not listen very much. My system sucks, so no sense trying to do any critical listening.

Now, my friend takes them home, and reports he gets a hum. He lives a bit away, so it is not easy for me to diagnose in person. What I do know is that he lives in an old house where the house wiring does not have a ground.

Should I do anything differently if the amp plugs into a two prong socket? He is using a cheater plug.

Dunno the usual stuff. Dunno if the hum stops if he touches the amp. Dunno if it hums with the linestage disconnected. Dunno if the hum follows volume. Dunno if it 60hz or 120hz. Working on that info. Just wondering about the 2 prong socket in general, I guess.

BTW, other than the hum, he really likes it. I may have displaced a Pass Aleph. For $55, it is really an amazing kit.

Thanks!
-e