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.

By Jean-Michel Falligan Devergne · Reviewed May 29, 2026

←6L6G

← 6KX8 6L6GC →Compare → 6L6GC

6L6G Tetrode Vacuum Tube

Tetrode6.3V / 0.9AOctalSPICE

SourceRCA datasheetReviewed2026-05-29StatusDataModelCalcModelKoren v1PDF

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

Datasheet ↗SPICE

6L6G — RCA — tetrode vacuum tube — (1936)

22.5kΩ

6.0mA/V

11.5pF

0.9pF

9.50pF

GAIN8%

POWER48%

DRIVE78%

LINEARITY95%

SPECIFICATIONS

Heater6.3 V · 0.9 A

Max Plate Voltage360 V

Pa max19 W

Gain Factor8

gm6 mA/V

rp22.5 kΩ

Inter-electrode capacitances

Cgk11.5 pF

Cgp0.9 pF

Cpk9.5 pF

PinoutOctal

Era1936

RarityModerate

HEATER6.3V / 0.9A

MAX PLATE360V / 19W

BASEoctal

Source datasheets

3 manufacturer datasheets cross-checked for 6L6G

3 verified

Triode-connectedSYLVANIAMarch 1954

Specs when the screen grid (g2) is tied to the anode — the tube acts as a triode.

250 V

Vg1

-20 V

5000 kΩ

Pout

1.4 W

THD

5 %

According to SYLVANIA (Electric Products Inc., Radio Tube Division, Emporium PA) — Engineering Data Service (March 1954): « Triode Connection »

EXECUTIVE SUMMARY

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.

APPLICATIONS

High-power output

Zenith console radiosRCA MI-12246 theatre amp

VS 6L6GC

μ 0%Rp +0%Pd -37%Full comparison →

HISTORY

Introduced1936ManufacturerRCA

Pre-War