What is the EL33 vacuum tube?

The EL33 (EL33 / 6M6G) is a pentode vacuum tube designed for power (se) applications. Classic octal output pentode. Rich harmonics..

What is a EL33 substitute or equivalent?

Direct equivalents to the EL33 include 6M6G, CV1853. 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 EL33?

Amplification factor μ ≈ 23, transconductance gm ≈ 9 mA/V, plate resistance rp ≈ 50.0 kΩ, max plate voltage 250 V, max plate dissipation 9 W, heater 6.3 V / 0.9 A.

Is the EL33 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the EL33 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 EL33 sound like?

Classic octal output pentode. Rich harmonics.. 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

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EL33 EL33 / 6M6G Pentode Vacuum Tube

Pentode6.3V / 0.9AOctal

SourceMullard·PhilipsReviewed2026-05-29StatusDataModelCalcModelunder reviewPDF

Small-signal pentode for low-noise voltage amplification

Datasheet ↗

EL33 / 6M6G — Mullard·Philips — pentode vacuum tube — (1938)

50.0kΩ

9.0mA/V

8.0pF

1.0pF

8.50pF

GAIN23%

POWER23%

DRIVE50%

LINEARITY89%

SPECIFICATIONS

Heater6.3 V · 0.9 A

Max Plate Voltage250 V

Pa max9 W

Gain Factor23

gm9 mA/V

rp50.0 kΩ

Inter-electrode capacitances

Cgk8 pF

Cgp1 pF

Cpk8.5 pF

PinoutOctal

Era1938

RarityModerate

HEATER6.3V / 0.9A

MAX PLATE250V / 9W

BASEoctal

Source datasheets

3 manufacturer datasheets cross-checked for EL33 / 6M6G

3 verified

Triode-connectedMullardn/a (Issue 2)

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

250 V

Vg1

-8.5 V

20 mA

6.5 mA/V

5.9

7 Ω

According to Mullard (ISSUE 2; code EL33 1546) — different print run of same Mullard data as 858 (n/a (Issue 2)): « g2 connected to a »

EXECUTIVE SUMMARY

The EL33 is a indirectly-heated pentode from Mullard·Philips, introduced around 1938. It provides a gain factor (μ) of 23 with 50.0kΩ plate resistance. Commonly used in power (se) applications. Classic octal output pentode. Rich harmonics.

HISTORY

Introduced1938ManufacturerMullard·Philips

Pre-War

EL33 Datasheet

Local mirror · PDF

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METRIX TESTER

Test this tube on a Metrix

SPICE model not yet available. Loadline calculator requires calibrated Koren parameters.

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