tech corner

Biasing

Please read before proceeding . . .

  • Everytime you have to change your power tubes, your amp needs to be rebiased (the idle current).
  • Our suggestion for all users who want to bias their amps theirselves: use a tool like Webers "Bias Rite" adaptor. www.tedweber.com
  • European users can buy a simple bias adaptor (DMM needed) at Tube Town www.tubetown.de
  • Feel free to ask any questions, esp. in our support forum (Rig Talk).
  • Diezel's suggestions for pairwise plate biasing currently (!) are:
  • EL34: 70 mA per pair

Preamp-Tube-Layouts

 

all models: V1 is always closest to the input jack (looking from the back of the amp on its right side)

 

VH4:

V1  Used by all channels

V2  Used by channel 4

V3  Used by channel 2/3/4

V4  Used by all channels

V5  Mixer and Send buffer

V6  Return driver

V7  Phase Inverter

Herbert:

V1  Used by all channels

V2  Used by channel 3

V3  Used by all channels

V4  Mixer & Loop Driver

V5  Return Driver

V6  Phase Inverter

Einstein:

V1  Used by both channels

V2  Used by channel 2

V3  Used by both channels

V4  Mixer & Loop Driver

V5  Return Driver

V6  Phase Inverter

V7 (just combo) Reverb (12AT7)

Schmidt

V1 = all channels
V2 = all channels
V3 = reverb
V4 = loop
V5 =phase inverter