http://www.dougstubes.com/ruby-12ax7...igh-grade.html

Ruby Tubes 12AX7AC5

Are these correct for v1 or v2, v3?


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
Phase Inverter buffer.
MUST USE ONLY 12AT7.
12AT7 China