The tubes in a GSP-2101 are 2 x 12AX7.
These are preamp tubes which do not have to be "matched" or "balanced".
There is nothing special about the tubes that came "stock" with a new
GSP-2101. I believe the stock tubes in a 2101 Artist were from Groove
Tube. There are several manufacturers making new 12AX7 tubes, each with a
slightly different construction and therefore a slightly different
tone.
Where to buy 12AX7 tubes? I have
bought several different kinds of 12AX7 from Doug's Tubes. Doug Preston
has a good selection, competitively priced, and he ships promptly:
----- Original Message -----From: M MSent: Saturday, June 18, 2011 10:57 PMSubject: [gsp-2101]
So recently my 2101 gets all squeelie when I run a lot of gain through the tubes. I think they're going microphonic. I'd like to try a new set of tubes but am not sure where to get replacements and what kind to get. I'd like to return it to a stock sound.
I believe my unit is running the stock GT tubes (groove tubes).
Anyone have a source and what is involved in changing them? Do I have to bias anything or what?
"Never put off till tomorrow what you can ignore entirely."