What is the 6L6G vacuum tube?

The 6L6G is a tetrode vacuum tube designed for power (pp) applications. Original glass 6L6..

What is a 6L6G substitute or equivalent?

Direct equivalents to the 6L6G include 6L6GC. 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 6L6G?

Amplification factor μ ≈ 8, transconductance gm ≈ 6 mA/V, plate resistance rp ≈ 22.5 kΩ, max plate voltage 360 V, max plate dissipation 19 W, heater 6.3 V / 0.9 A.

Is the 6L6G still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6L6G as Moderate 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 6L6G sound like?

Original glass 6L6.. 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.

6L6G Tetrode Vacuum Tube

Also known as 6L6GC

Beam power tetrode rated at 19W for high-power output stages

TetrodeHeater 6.3 V · 0.9 AOctalRCA 1936

Plate dissipation: 19W
Max plate voltage: 360V
Transconductance: 6mA/V

6L6G

Characteristics

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

HeaterIndirectly heated

Specifications of 6L6G — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.9 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6L6G — Limiting values
Plate voltageVa max	360 V
Plate dissipationPa max	19 W
Screen dissipationPg2 max	2.5 W

Mechanical

Specifications of 6L6G — Mechanical
Base	Octal
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6L6G — Small signal
Transconductance	6 mA/V
Plate resistance	22.5 kΩ
Amplification factor	8

Capacitances

Specifications of 6L6G — Capacitances
Input	11.5 pF
Grid–plate	0.9 pF
Output	9.5 pF

Charactereditorial reading, not a measurement

Specifications of 6L6G — Character
Gain	8%
Power	48%
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	Va	Vg2	Vg1 / Rk	Ia	Ig2	Load	Pout	THD	gm	μ	rp	Source
triode connection, single-endedclass not stated · fixed bias	250 V		-20 V	40 mA			1.4 W			2		read on the sheet TUNG-SOL · 1952 · transcript
Class A, single-endedpentode connection · fixed bias	250 V	250 V	-14 V	72 mA	5 mA	2.5 kΩ	6.5 W	10%	6 mA/V		22.5 kΩ	OCR, to be checked TUNG-SOL · 1952 · 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		OCR, to be checked TUNG-SOL · 1952 · p. 2 · 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%				OCR, to be checked TUNG-SOL · 1952 · p. 3 · transcript

Using this tube

Applications

High-power output

Zenith console radiosRCA MI-12246 theatre amp

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : RCA datasheetActive model : Koren v1

Manufacturer datasheets

3 manufacturer datasheets cross-checked for 6L6G3 verified

Triode-connectedSYLVANIAMarch 1954

Va: 250 V
Vg1: -20 V
µ: 5
RL: 5000 kΩ
Pout: 1.4 W
THD: 5 %

6L6G DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: RCA datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Koren v1

Context

The 6L6G is a indirectly-heated beam tetrode from RCA, introduced around 1936. It provides a gain factor (μ) of 8 with 22.5kΩ plate resistance. Commonly used in power (pp) applications. Original glass 6L6.

History

Introduced: 1936
Manufacturer: RCA
Era: Pre-War

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