R Series V1.0 p 25
Chubster 55, Suprema, R55-112
V1 V2 V3
V4 V5
V7
V6
Location Type
V1
12AX7
V2
12AX7
V3
12AX7
V4
12AX7
V5
12AX7
V6
EL-34
V7
EL-34
Here's a brief description of what each tube does:
V1 Input buffer and tone control driver for Channel 2, and also the first preamp stage of
Channel 1
V2 Tone control follower for Channel 2 and an additional gain stage for Channel 1
V3 Final stages for both channels before the mixer stage
V4 Reverb follower and the mixer stage, provides gain to the reverb pan
V5 Phase inverter driver tube for the power amp section
V6, V7 Power amp tubes--for best operation, they should always be changed in pairs
General information about tube types
EL-34 is the most common European type of Power Output Tube. There are 4 factories
in the world building this tube; Svetlana in St. Petersburg, Russia, Reflector (Sovtek) in
Russia, JJ/Tesla in Slovenia, and a factory in China. NOS (New old stock) supplies from
various other factories are still available, albeit in short supply. Out of all that are
currently made, we have had the best success with the Svetlana.. The tone of EL-34’s
is very different from 6L6GC. We are very critical in our testing of our tubes, and throw
away many that do not make our grade. All of our amps are built with matched tubes,
that are graded as well. When you need to purchase replacement tubes, if you order the
same grade number that are in your amp originally from the factory (provided that no
one has changed the bias set at the factory), you can change out the tubes without
needing the bias to be re-adjusted. If you use tubes not from us or of a different grade
or value, you will need to have the amp rebiased. In terms of 12AX7A types, there are
only 3 factories that we know of building this tube type; JJ/Tesla, Sovtek, and Ruby
Tubes in China. Again, NOS stocks still exist of RCA, G.E., Mullard, Telefunken,
