AstroStrat89
Member
- Messages
- 306
Fender Pro Junior, been in for filter caps once already.
Had some old RCAs in all four positions (2 x 12ax7 and 2 x el84) The amp started to make a hum noise. It would make the noise with nothing plugged into the amp and the volume had no effect on the hum. Just always there in the background.
Now here is were it gets a little strange. If you think about the volume knob starting at 0 and then going to 1 then 2 and 3 etc. In this case it was like my volume started at 1 then 0 then 1,2,3, etc. So turned all the way down was like having it on volume 1, then as I turned it up the volume would go down for a brief part of the sweep and then begin to go up and behave normally.
So instead of
0123456...
It worked like
10123456...
Now it get even more interesting.
I put all of the stock GT tubes back in and all these issues just go away. Bad tubes right? Well hold on.
I ordered a new pair of GTs el84s and 1 GT 12ax7-c for V1 (figuring it wouldn't matter what was in V2 as long as it worked). Remember at this point the amp is working fine with the stock GTs in all positions, I just want better tubes.
I swap all of the tubes (using one of the stock GTs for V2) and all these weird issue came back.
Come to figure out that its all in the V1 tube. I have 5 12ax7s. Two of them work just fine, the stock GT and a JJ's that I had. Both of the RCAs and the new GT 12ax7c have the issue. It doesn't seem to matter what is in V2 or what power tubes (new GTs, stock GTs, RCAs)
Is it the amp? How could 50 year old tubes have the same issue as a new production GT.
Had some old RCAs in all four positions (2 x 12ax7 and 2 x el84) The amp started to make a hum noise. It would make the noise with nothing plugged into the amp and the volume had no effect on the hum. Just always there in the background.
Now here is were it gets a little strange. If you think about the volume knob starting at 0 and then going to 1 then 2 and 3 etc. In this case it was like my volume started at 1 then 0 then 1,2,3, etc. So turned all the way down was like having it on volume 1, then as I turned it up the volume would go down for a brief part of the sweep and then begin to go up and behave normally.
So instead of
0123456...
It worked like
10123456...
Now it get even more interesting.
I put all of the stock GT tubes back in and all these issues just go away. Bad tubes right? Well hold on.
I ordered a new pair of GTs el84s and 1 GT 12ax7-c for V1 (figuring it wouldn't matter what was in V2 as long as it worked). Remember at this point the amp is working fine with the stock GTs in all positions, I just want better tubes.
I swap all of the tubes (using one of the stock GTs for V2) and all these weird issue came back.
Come to figure out that its all in the V1 tube. I have 5 12ax7s. Two of them work just fine, the stock GT and a JJ's that I had. Both of the RCAs and the new GT 12ax7c have the issue. It doesn't seem to matter what is in V2 or what power tubes (new GTs, stock GTs, RCAs)
Is it the amp? How could 50 year old tubes have the same issue as a new production GT.