What is the 6L6GC vacuum tube?

The 6L6GC is a tetrode vacuum tube designed for power (pp) applications. American workhorse..

What is a 6L6GC substitute or equivalent?

Direct equivalents to the 6L6GC include 5881, 7027A. These share the same pinout and operating envelope, so they can usually be swapped without circuit changes — though batch-to-batch variations between manufacturers (NOS vs current production) may shift the sonic character noticeably.

What are the key specifications of the 6L6GC?

Amplification factor μ ≈ 8, transconductance gm ≈ 6 mA/V, plate resistance rp ≈ 22.5 kΩ, max plate voltage 500 V, max plate dissipation 30 W, heater 6.3 V / 0.9 A.

Is the 6L6GC still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6L6GC as Common availability. NOS (new-old-stock) examples from RCA, Mullard, Tung-Sol, GE, Sylvania and Telefunken trade among collectors; modern production where it exists comes mostly from JJ Electronic, Electro-Harmonix, Tung-Sol (New Sensor), Genalex, and a handful of small-batch makers.

What does the 6L6GC sound like?

American workhorse.. Sonic character also depends heavily on the circuit operating point, the surrounding tubes in the stage, and the output transformer when present — use the interactive loadline calculator on this page to explore the trade-offs.

6L6GC Tetrode Vacuum Tube

Also known as 5881 · 7027A

Beam power tetrode rated at 30W for high-power output stages

TetrodeHeater 6.3 V · 0.9 AOctalGE·Sylvania·RCA 1958

Plate dissipation: 30W
Max plate voltage: 500V
Max screen voltage: 450V
Transconductance: 6mA/V

6L6GC

Characteristics

Datasheet values, once each. Every value cites its sheet.

HeaterIndirectly heated

Specifications of 6L6GC — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.9 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6L6GC — Limiting values
Plate voltageVa max	500 V
Screen voltageVg2 max	450 V
Plate dissipationPa max	30 W
Screen dissipationPg2 max	5 W
Heater–cathode voltageVhk max	200 V

Mechanical

Specifications of 6L6GC — Mechanical
Base	Octal
Rarity	Common
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6L6GC — Small signal
Transconductance	6 mA/V
Plate resistance	22.5 kΩ
Amplification factor	8

Capacitances

Specifications of 6L6GC — Capacitances
Input	10 pF
Grid–plate	0.6 pF
Output	6.5 pF

Charactereditorial reading, not a measurement

Specifications of 6L6GC — Character
Gain	8%
Power	75%
Drive	78%
Linearity	95%

datasheet cited · model or editorial reading · catalogue value, no citation attached yet · nothing invented

Typical operation

Conditions published by the manufacturers, one row per condition. Nothing is computed.

Typical operation
Setup	B+	Va	Vg2	Vg1 / Rk	Ia	Ig2	Load	Pout	THD	gm	μ	rp	Source
Class A, single-endedpentode connection · fixed bias		200 V	200 V	-11.5 V	52 mA	3.5 mA	3 kΩ	4 W	9%	5.3 mA/V		35 kΩ	OCR, to be checked RCA · 1960 · p. 2 · transcript
Class A, single-endedtriode connection · fixed bias	250 V			-20 V	40 mA		5 kΩ	1.4 W	5%	4.7 mA/V	8	1.7 kΩ	OCR, to be checked RCA · 1960 · p. 3 · transcript
Class A, push-pullpentode connection · fixed bias · values for two tubes	250 V		250 V	-16 V	120 mA	10 mA	5 kΩ a-a	14.5 W	2%	5.5 mA/V		24.5 kΩ	OCR, to be checked RCA · 1960 · p. 3 · transcript
Class AB1, push-pullpentode connection · fixed bias · values for two tubes	360 V		270 V	-22.5 V	88 mA	5 mA	6.6 kΩ a-a	26.5 W	2%				OCR, to be checked RCA · 1960 · p. 4 · transcript

Design a stage →

Using this tube

Applications

High-power output

Fender Twin ReverbFender BassmanMesa Boogie Mark series

Guitar ampPA/public address

Featured in these amplifiers

Classic circuits

Fender Bassman
Guitar Amp45W
Fender 5F6-A Bassman (1958-60). Fixed-bias 6L6GC push-pull. The amplifier that launched a thousand designs. Foundation of Marshall and Mesa.
PPVb 430V · Vg -45V · Vg₂ 410V · RL 4kΩFender 5F6-A Schematic
Mesa Boogie Mark Series
Guitar Amp60W
Randall Smith's high-gain design. Fixed-bias 6L6GC with cascaded gain stages. Tight, focused overdrive with scooped mids. Carlos Santana, Metallica.
PPVb 480V · Vg -48V · Vg₂ 460V · RL 4.2kΩMesa Boogie Mark Series Schematic
Fender Twin Reverb
Guitar Amp85W
Fender's flagship clean amplifier. Fixed-bias 6L6GC push-pull with spring reverb. Pristine headroom and sparkling cleans. The studio standard.
PPVb 470V · Vg -47V · Vg₂ 450V · RL 4kΩFender Twin Reverb Schematic (AB763)

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : GE·Sylvania·RCA datasheetActive model : Norman Koren

Manufacturer datasheets

7 manufacturer datasheets cross-checked for 6L6GC7 verified

6L6GC DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: GE·Sylvania·RCA datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Norman Koren

Context

The 6L6GC is the heavy-duty version of the 6L6 beam power tetrode, originally developed by RCA and later adopted as the defining output tube of American amplifier design. It delivers 30-50W per pair in push-pull with a clean, tight, punchy sound characterized by strong bass, scooped mids, and crisp highs compared to the more midrange-focused EL34. The 6L6GC is the sound of Fender Twin Reverbs, Mesa Boogies, and virtually every American-voiced guitar and hi-fi amplifier. GE, RCA, Sylvania, and Tung-Sol made the most respected NOS versions; current production from various manufacturers is abundant.

History

Introduced: 1958
Manufacturer: GE·Sylvania·RCA
Era: Golden Age

METRIX TESTER

Characteristics

HeaterIndirectly heated

Limiting valuesDatasheet maximum ratings — not to be exceeded

Mechanical

Small signalDatasheet parameters at the reference operating point — not limits

Capacitances

Charactereditorial reading, not a measurement?

Typical operation

Using this tube

Applications

Featured in these amplifiers

Classic circuits

Fender Bassman

Mesa Boogie Mark Series

Fender Twin Reverb

Replace or compare

Direct equivalents

Versus EL34

Comparisons

Similar tubes