TUBE FUNCTION AND LOCATION CHART
Preamp tube locations are indicated by tube type on the rear panel of the chassis. Tube types are factory
selected for superior performance, consistent tone quality and reliability. While substituting other brands may
not cause damage to the amplifier this may affect amplifier performance in unpredictable ways. For best
performance, replace only with factory recommended tubes.
Warning!
Substituting other tube types is not
recommended.
Each 12AX7 has two sections/functions. Section A is shown first, Section B is second. Factory recommended
tubes are listed under each location. Numbering sequence is right to left looking at back of amp starting with
the row closest to front panel of amp.
V1 (shielded tube)
Input Gain Stage 1 (Parallel Triodes).
12AX7A Tung-Sol
12AX7WB Sovtek
Use in place of Tung-Sol for smoother top end and less upper mids.
12AX7 China Selected
Use in place of WB if more gain is required.
V2 (shielded tube)
Gain Stage 2.
12AX7A/7025 China
Gain Stage 4. Active only when MORE / LESS switch is set to MORE.
V3 (shielded tube)
Gain Stage 3.
12AX7A/7025 China
Tone Control Driver.
V4 Phase
Inverter.
12AX7A/7025 China
V5 – V6
Power Tubes
MUST USE ONLY KT88 or 6550.
KT88 Sovtek
NOT INTERCHANGEABLE WITH ANY OTHER TUBE TYPES!
KT88 EH
KT88 Svetlana
6550 Sovtek
6550 Svetlana
