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.

EL33 6M6G Pentode Vacuum Tube

Also known as 6M6G · CV1853

Small-signal pentode for low-noise voltage amplification

PentodeHeater 6.3 V · 0.9 AOctalMullard·Philips 1938

Plate dissipation: 9W
Max plate voltage: 250V
Max screen voltage: 300V
Max cathode current: 55mA
Transconductance: 9mA/V

EL33

Characteristics

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

HeaterIndirectly heated

Specifications of EL33 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.9 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of EL33 — Limiting values
Plate voltageVa max	250 V
Screen voltageVg2 max	300 V
Plate dissipationPa max	9 W
Cathode currentIk max	55 mA
Grid resistorRg1 max	1 MΩ
Peak plate voltageVao	550 V

Mechanical

Specifications of EL33 — Mechanical
Base	Octal
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of EL33 — Small signal
Transconductance	9 mA/V
Plate resistance	50 kΩ
Amplification factor	23

Capacitances

Specifications of EL33 — Capacitances
Input	8 pF
Grid–plate	1 pF
Output	8.5 pF

Charactereditorial reading, not a measurement

Specifications of EL33 — Character
Gain	23%
Power	23%
Drive	50%
Linearity	89%

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	250 V		-8.5 V	20 mA		7 Ω			6.5 mA/V	5.9		read on the sheet Mullard · n/a (Issue 2) · transcript
Class A, single-endedpentode connection	250 V	250 V	-6 V	36 mA	4 mA	7 kΩ	4 W	10%	9 mA/V		50 kΩ	OCR, to be checked Mullard · n/a (Issue 2) · p. 1 · transcript
pentode connection, single-endedclass not stated	250 V	250 V	-6 V	36 mA	4 mA	7 kΩ		10%	9 mA/V		50 kΩ	OCR, to be checked Mullard · n/a (Issue 2) · p. 1 · transcript
pentode connection, push-pullclass not stated · cathode bias	250 V	250 V	140 Ω	24 mA	2.8 mA	10 kΩ a-a	8.2 W	3.1%				OCR, to be checked Mullard · n/a (Issue 2) · p. 1 · transcript

Using this tube

Interactive loadline calculator not available for this tube yet — it needs calibrated Koren or Ayumi parameters.

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026

Manufacturer datasheets

3 manufacturer datasheets cross-checked for EL33 / 6M6G3 verified

Triode-connectedMullardn/a (Issue 2)

Va: 250 V
Vg1: -8.5 V
Ia: 20 mA
gm: 6.5 mA/V
µ: 5.9
Ra: 7 Ω

EL33 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Mullard·Philips
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

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

Introduced: 1938
Manufacturer: Mullard·Philips
Era: Pre-War

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