Faint humming sound constantly in background

[atul.mehta6]

Hi All,

I've a interesting situation here. I've got my Crack + SB combo up and running for a few months now. Then I contracted a bad case of the good ol' tube rolling disease So I was trying a bunch of tubes in place of the stock 6080 tube. With every tube I tried, the background has been constantly dead quiet except when I use the RCA 6AS7G one. Then I hear a constant background humming sound even with no RCA connected and volume knob turned all the way down. Is it a quirk of the RCA tube or perhaps I got a bum tube? Any idea?

Thanks,
Atul

 

[Doc B]

It's that individual tube. A good RCA would be just as quiet as any other 6AS7/6080.

 

[Jameson]

Agreed. I rolled in an RCA 6AS7G just last week and it's dead quiet.