[jjhatfield]

The title pretty much says it all. I recently acquired an RCA 6sn7 grey glass which I'm using in my Slam. It sounds wonderful, only there is just the teeniest hum in my right ear only when using it. As soon as I switch out the 6sn7 with another tube the hum goes away.

I don't like the hum, but it isn't ruining my enjoyment of the music. I'd just like to make sure this isn't doing any damage to my PPX3. Thanks!

Quick edit: the hum is louder and more pronounced with my Grados and my HD595, much less so with the 600 and 650.

 

[jjhatfield]

I take it back, I do mind the hum. Bah! The tube appears to be microphonic. When I tap the amp near the tube I can hear my tap in both ears.

 

[nikongod]

got tube dampers? unless the tube is VERY bad they may help.

i have a bad 12au7 that they helped, but did not cure. its was worth a shot.

 

[sacd lover]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif got tube dampers? unless the tube is VERY bad they may help. i have a bad 12au7 that they helped, but did not cure. its was worth a shot.

Take a soft wire brush and scrub the tube pins. If you have some de-oxit or high temperature lubricant clean the pins with the lubricant. Make sure you wipe of all the excess. See if the hum is a poor connection.

If the tube is microphonic go to an auto parts store and buy some high temperature O rings that fit the tube; you may want to take a tube along to make sure of the fit. Stack three even four mainly at the middle to the top of the tube around the top mica spacer. See if that doesnt atleast help if not resolve the problem.