Basing (pinout)
Bottom view — the socket as you see it from the wiring side. Hover, tap, or focus a pin to name it. Read from the datasheet basing diagram (how to read these →).
Hover, tap, or focus a pin to name it.
- High voltage (B+)
- Control grid
- Cathode
- Heater / filament
Viewed from below (socket / wiring side) · noval 9-pin (B9A) · basing 9A
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Datasheets
Primary manufacturer data, via public tube-data archives. The model below is fitted to the tabulated "average characteristics" in these sheets; the datasheet files themselves are linked, never rehosted.
| Publisher | Type | Source |
|---|---|---|
| RCA | 12AX7A | frank.pocnet.net ↗ |
| General Electric | 12AX7 | frank.pocnet.net ↗ |
| Tung-Sol | 12AX7 | frank.pocnet.net ↗ |
| Sylvania | 12AX7 | frank.pocnet.net ↗ |
| Philips | ECC83 | frank.pocnet.net ↗ |
Circuit Codex model
A CC0 ngspice model in the Koren form, fitted here to the published anchor — no parameters copied from other model collections. Methodology →
- Anchor
- Va=250 V, Vg=-2 V → Ia=1.2 mA, gm=1600 µmho, µ=100
- Source
- RCA Receiving Tube Manual RC-19, 1959, average characteristics
- Note
- Two-point fit (adopted 2026-07-18 from the calibration study below): the plate-current curve is held at both tabulated operating points — 250 V/−2 V and 100 V/−1 V — which all four manufacturers print identically. The low-plate-voltage behaviour of this tube was the subject of the 12AX7 calibration study.
- File
- models/12ax7.inc ↗