← Reference

6L6GC

also 6L6-GC

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. It shares the 6L6 family's 7AC octal basing with the 6L6G and the 5881, and drops into either socket; the reverse does not hold, because both of those are rated below it.

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 →).

1 2 3 4 5 6 7 8

Hover, tap, or focus a pin to name it.

  • High voltage (B+)
  • Control grid
  • Cathode
  • Heater / filament
  • No connection

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.

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.

PublisherTypeSource
RCA 6L6-GC frank.pocnet.net ↗
General Electric 6L6GC frank.pocnet.net ↗
Tung-Sol 6L6GC 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, Vg2=250 V, Vg1=−14 V → Ia=72 mA, Ig2=5 mA, gm=6000 µmho
Source
RCA 6L6-GC data sheet, DATA 1, 8-60, Class A1 characteristics
Note
µ is the grid-No.1-to-grid-No.2 amplification factor (8) printed in RCA's RC-19 manual; the 6L6-GC sheet itself prints none. The fit lands on the same numbers as models/5881.inc, because the 5881 is the ruggedized 6L6GC and RCA prints one set of Class A1 characteristics for both. The two are carried as separate models because their maximum ratings are not the same tube's, and every rating the load-line explorer overlays is read from the model's own entry here.
File
models/6l6gc.inc ↗

See these parameters drawn: the load line explorer plots the 6L6GC's plate-curve family from this model and solves an operating point on it.

Maximum ratings

Design-maximum values from the RCA 6L6-GC sheet's Class A1 AF-power-amplifier table. This is the headroom that separates the 6L6GC from the rest of the family: the 5881 is rated 23 W / 400 V and the original 6L6G lower still, so a rating figure borrowed from either understates what this tube is rated for.

Plate dissipation
30 W
Plate voltage
500 V
Screen (grid No.2) voltage
450 V
Screen (grid No.2) input
5 W
Rating system
Design maximum — the line no individual valve may cross
Source
RCA 6L6-GC data sheet (design-maximum system) ↗