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New source of hum [message #97669] Mon, 29 April 2024 21:16 Go to next message
gofar99 is currently offline  gofar99
Messages: 1916
Registered: May 2010
Location: Southern Arizona
Illuminati (5th Degree)
Hi everyone. I posted this elsewhere to cover some additional folks that might benefit from it.

Once in a while we do something that is apparently simple and won't cause any problems. So I did a bit of tidy up in my main phono preamp. Unfortunately it caused hum. Not a lot, but audible at full gain setting and right in front of the huge subs. It was just audible. Since I really hate hum I did the logical thing and hauled it to the bench to see what went south. Remove the cover and wow ...how dumb can one get?. There is was staring me right in the face. I spray painted the tube shields to match the copper color of the Audyn copper caps. Yes it dribbled into the small gaps that hold the shields in place. And with no surprise it nicely insulated the shields from the bases. A bit of Dremel work and all is now back to normal. The only sound now is that of quiet. No noise no hum. I hope I have helped someone out there from making the same goof. BTW some new socket shields have the same problem. I ran into a batch of anodized ones that had the same issue....bad contact between socket and shield so beware of the issue. Same cure


Good Listening
Bruce
Re: New source of hum [message #97670 is a reply to message #97669] Mon, 29 April 2024 21:27 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18707
Registered: January 2001
Illuminati (33rd Degree)

Good catch, Bruce!
Previous Topic: NOS 6NC3 vs 6N3C-E Output Tubes
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