Data: MediumMedium quality — at least 60% of universal parameters and pins are present, but some key data is missing. Verify specific values against datasheets before critical use.
Indirectly heated regulator beam tetrode with near-identical operating characteristics (gm 14 vs 13.5 mA/V, Pa_max 35 vs 28W), but S11E12 has anode on base pin 3 (IO socket) rather than top cap — not pin-compatible without rewiring.
Anode connects to a top cap (American miniature type), not to a base pin. Requires a top-cap clip lead or adapter.
Originally designed as a voltage regulator series-pass tube for stabilised power supplies, intended for parallel operation of multiple tubes. The datasheet typical operating conditions (Va=Vg2=150V, Ia=200mA) reflect regulator service, not audio use.
Screen grid is limited to 300V maximum — considerably lower than many audio beam tetrodes. In audio circuits, B+ voltages must be chosen carefully to avoid exceeding this rating, especially in cathode-biased designs where screen voltage can rise.
Triode-strapped mu is only 5.5, requiring significant drive voltage. At higher anode voltages (above 300V) the plate curves compress severely and bias voltage becomes very large, making the tube impractical above ~300V in triode mode.
A ruggedised variant, the 12E1R, was also produced.
The 12E1C is listed as an improved successor variant.
Pin Layout — Octal
1No Connection
2Heater
3No Connection
4
Socket-Compatible Tubes ⚠ Not electrically compatible