Every tube in this archive, drawn as a bottom-view socket. Hover, tap, or focus a pin to name it — grouped by base so the shared wiring is easy to see. The pins that carry B+ are marked in oxblood.
It's a bottom view. Each diagram shows the tube from underneath — the way the socket faces you from the solder side while you wire it. Turn a real tube over and its pins line up with the drawing. (Look at the tube from the top instead and the order mirrors, which is how miswired sockets happen.)
Find the index, then count clockwise. A noval or 7-pin miniature tube has a wider gap in its ring of pins; an octal tube has a keyed centre spigot. Hold that gap or key at the bottom, and pin 1 is the first pin to its left. The numbers run clockwise from there — up the left side, across the top, down the right.
The code is a standard. The short label on each diagram — 9A, 7BT, 7AC, 5T, 5DA — is the RETMA/EIA basing designation: a fixed name for one arrangement of elements on the pins. Tubes that share a code share a socket wiring, which is why the 6V6GT, 5881, and KT66 all read 7AC and drop into the same output-stage layout. Every map here is read straight from the manufacturer datasheets linked on each tube's page.
The small-button nine-pin base, doing every job in the amplifier. 6CG7, 12AT7, 12AU7, 12AX7 and 12AY7 are twin triodes — two independent gain stages in one glass, their pins interleaved around the ring — while the 5879 and EF86 are single preamp pentodes, the 6973 and EL84 are output tubes, and the EZ81 is a rectifier. Same base, different sockets: check the code before assuming a shared wiring.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · noval 9-pin (B9A) · basing 9AJ
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Medium-mu (µ=20) nine-pin twin triode — electrically the 6SN7 rebuilt on a noval base when the industry left the octal behind, and rated to pass real current: 9 mA a section at 250 V, 4 W a plate.
Hover, tap, or focus a pin to name it.
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.
High-mu (µ=60) twin triode with low plate resistance and high transconductance — a strong current driver.
Hover, tap, or focus a pin to name it.
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.
Medium-mu (µ=17) dual triode — the low-gain, low-impedance member of the 9A-based twin-triode family.
Hover, tap, or focus a pin to name it.
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.
High-mu (µ=100) dual triode — the universal gain stage, cathode follower, and phase inverter of guitar amplification.
Hover, tap, or focus a pin to name it.
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.
Medium-mu (µ=44) dual triode — a lower-gain, lower-noise first stage.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · noval 9-pin (B9A) · basing 9AD
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
RCA nine-pin sharp-cutoff pentode, built for the one job its sheet names in the title: audio-amplifier applications critical as to microphonics, leakage noise and hum.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · noval 9-pin (B9A) · basing 9EU
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
RCA beam power tube in a 9-pin miniature bottle — the output valve of the Supro and Valco amplifiers, and the reason those amps sound the way they do.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · noval 9-pin (B9A) · basing —
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Philips/Mullard A.F.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · noval 9-pin (B9A) · basing 9CV
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Philips/Mullard A.F.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · noval 9-pin (B9A) · basing 9M
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Philips/Mullard indirectly-heated full-wave rectifier in a noval bottle — the rectifier of the Vox AC15 and of the AC30 line beside it.
The seven-pin miniature base — one detector-triode preamp tube in this corpus. Only the triode plate carries B+; the two diode plates sit idle here.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · miniature 7-pin (B7G) · basing 7BT
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Twin-diode / high-mu (µ=70) triode.
The same octal shell doing small-signal work, a watt or two of plate dissipation instead of twenty. Each carries its own arrangement rather than a shared one: the 6SJ7 brings grid No.1 out on a base pin instead of a top cap, and the 6SL7GT spends all eight pins on two complete triodes — grid, plate and cathode of one unit on pins 1 to 3, the other on 4 to 6.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 8N
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
RCA metal sharp-cutoff pentode — the octal preamp valve of the wide-panel tweed era, before the 9-pin 12AX7 took the front end over.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 8BD
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
High-mu (µ=70) twin triode on an octal base — the octal counterpart of the 9-pin 12AX7, and the preamp and phase-inverter bottle of the Ampeg circuits.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 8Q
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Octal double-diode high-mu triode — two diode plates and one µ=100 triode in one envelope, all three sections sharing a single cathode.
The eight-pin octal base with its keyed centre spigot. Most of these follow the 7AC arrangement — plate on 3, screen on 4, control grid on 5 — which is why a 6V6GT, 5881 and KT66 drop into the same output-stage layout. The EL34 (K8A) and the 7591 (8KG) do not: read their diagrams before rewiring a socket for either. On all of them both the plate and the screen sit at B+.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 7AC
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Beam-power output tube — the original coke-bottle 6L6/6L6G, lettered on the Fender 5F4 Super "C-EG" drawing.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 7AC
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
The top of the 6L6 beam-power line and the American output valve of the blackface era — a 30 W plate rating on a 500 V ceiling, which is what lets a quartet of them sit on the AB763 Twin Reverb's +460 V rail.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 7AC
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Beam-power output tetrode — the low-wattage American output tube.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 7AC
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
The ruggedized member of the 6L6 beam-power line — Tung-Sol's premium-quality 6L6, and the output tube the tweed 5F6-A Bassman is drawn around.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 8KG
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Beam power tube on an intermediate-shell octal base — the output valve Ampeg built its line around.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing K8A
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Mullard/Philips A.F.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 7AC
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
British beam-power tetrode from GEC / M-O Valve Co.
Same octal base, different job. In the directly-heated 5Y3 and 5U4 the filament is the cathode, so it floats at B+ alongside the plates; the GZ34 (5DA) adds a separate heater but ties its cathode to pin 8. On a rectifier, nearly every pin is hot.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 5T
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Directly-heated high-current full-wave rectifier — the supply rectifier of the larger tweed amps such as the 5F4 Super, where the 5Y3 could not pass enough current.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 5T
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Directly-heated full-wave rectifier — the low-current rectifier of the small tweed amps.
Hover, tap, or focus a pin to name it.
Viewed from below (socket / wiring side) · octal · basing 5DA
⚡ Oxblood pins sit at B+ — hundreds of volts in service, lethal, and still charged after power-off.
Indirectly-heated full-wave rectifier — a low-drop, slow-warmup rectifier that supplies the tweed 5F6-A Bassman and the JTM45.
Pin maps are transcribed from the manufacturer basing diagrams — RCA, GE, Tung-Sol, Mullard, Philips and GEC — linked on each tube's reference page, and cross-checked against a second sheet where one is available. The socket drawings are redrawn here, never traced from the source documents.