Voltage - Dual Triode (similar) ·Triode-Triode
12AX7LP
Sovtek 12AX7LP high-mu dual triode with 6.3/12.6 V selectable heater, nominal amplification factor 94 and 330 V maximum plate voltage, designed for linear audio amplification.
- Sections
- 2
- Base
- 9A
- Socket code
- -
- Base pins
- 9
- Nominal heater
- 12.6 V / -
General specifications
Tube and section characteristics
Properties common to every published source and operating point.
Heater and base
- Base
- 9A
- Socket code
- -
- Base pins
- 9
- Nominal heater voltage
- 12.6 V
- Nominal heater current
- -
- Parallel heater voltage
- 6.3 V
- Parallel heater current
- -
- Series capable
- Yes
9A - Terminal pinout
Electrical assignments shared by every tube using this base designation.
| Terminal | Section | Connection | Evidence |
|---|---|---|---|
| PIN12P | B | P — Plate (Anode) EIA transcription; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 130, 9A |
| PIN22G1 | B | G1 — Control Grid EIA transcription; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 130, 9A |
| PIN32K | B | K — Cathode EIA transcription; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 130, 9A |
| PIN4H | — | H — Heater EIA transcription; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 130, 9A |
| PIN5H | — | H — Heater EIA transcription; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 130, 9A |
| PIN61P | A | P — Plate (Anode) EIA transcription; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 130, 9A |
| PIN71G1 | A | G1 — Control Grid EIA transcription; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 130, 9A |
| PIN81K | A | K — Cathode EIA transcription; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 130, 9A |
| PIN9HCT | — | HCT — Heater Center Tap EIA transcription; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 130, 9A |
Section ratings
2 physical sections, each with unique specifications.
Section 1
Triode
- Plate resistance
- 56000 Ω
- Transconductance
- 0.0017 S
- Amplification factor
- 94
- Max plate voltage
- 330 V
- Max plate dissipation
- 1.2 W
Sovtek 12AX7LP triode 1. Nominal mu 94, gm 0.0017 A/V, rp 56000 Ω; max plate 330 V, dissipation 1.2 W, plate current 9 mA. Nominal grid-plate capacitance 1.7 pF, grid-to-cathode/heater 1.6 pF, plate-to-cathode/heater 0.46 pF, cathode-heater 5 pF; manufacturer prints plate-to-plate 600 pF (unusually high; verify). Maximum heater-cathode ±200 V, fixed-bias grid resistor 1 MΩ, self-bias 2.2 MΩ. Test at heater 12.6 V, plate 250 V, grid -2 V: minimum gm 0.0014 A/V, mu 78, plate current 0.75 mA, grid reverse current max 0.2 µA.
Section 2
Triode
- Plate resistance
- 56000 Ω
- Transconductance
- 0.0017 S
- Amplification factor
- 94
- Max plate voltage
- 330 V
- Max plate dissipation
- 1.2 W
Sovtek 12AX7LP triode 2. Nominal mu 94, gm 0.0017 A/V, rp 56000 Ω; max plate 330 V, dissipation 1.2 W, plate current 9 mA. Nominal grid-plate capacitance 1.7 pF, grid-to-cathode/heater 1.6 pF, plate-to-cathode/heater 0.38 pF, cathode-heater 5 pF; manufacturer prints plate-to-plate 600 pF (unusually high; verify). Maximum heater-cathode ±200 V, fixed-bias grid resistor 1 MΩ, self-bias 2.2 MΩ. Test at heater 12.6 V, plate 250 V, grid -2 V: minimum gm 0.0014 A/V, mu 78, plate current 0.75 mA, grid reverse current max 0.2 µA.
Source-dependent data
Operating conditions by source
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.