Tube config
Power valves: 2 x EL84s (Sovtek)
Preamp valves: 3 x electro-harmonix 12AX7EH - www.amplifiedparts.com/products/T-12AX7EH
Ultra module: 2 x 12AX7s (JJ) - www.amplifiedparts.com/products/T-12AX7-S-JJ
Speaker
Celestion G12M greenback
Modifications
Here are some possibilities:
- first gain stage: all modules must use the first gain stage that is built inside the Randall; Changing the cathode bypass (C1) from 22uF to a smaller value will raise the cut-off frequency.
Module tube choices
Warning! The tube in the V2 position is used by the module as a cathode follower. This tube is subjected to high voltages that not all 12AX7 tubes can handle. It is not recommended to use anything manufactured by New Sensor (ie: Tungsol and Mullard reissue, EH, Sovtek) in this position.