Noisy 3rd Channel on DR

[THE_L1ZARD_KING]

During the first few minutes my amp is on and on channel 3 it makes a hissing/popping noise that sounds like a vinyl record before the music starts. Is this normal for DR's or Tube amps? This is my first tube amp and I am trying to figure out what it par for the coarse and not. I have checked cables and gently tapped the tubes to see if one was microphonic. I also turned all the pots on the 3rd channel but that didn't make a difference. Thanks in advance for any help.

 

[clutch71]

I'd say start swapping out the preamp tubes. See if that solves it. Look at the tube schematic in the manual and see which one is responsible for that channel and start with it first.

 

[THE_L1ZARD_KING]

Hmm...I don't have any extra tubes at the moment but I plan on buying a set very shortly and will give it a shot. Thanks again.