What is the EF94 vacuum tube?

The EF94 (EF94 / 6AU6) is a pentode vacuum tube designed for preamp / if amp applications. European designation of the 6AU6 sharp-cutoff preamp/IF pentode..

What is a EF94 substitute or equivalent?

Direct equivalents to the EF94 include 6AU6, EF94. 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 EF94?

Transconductance gm ≈ 5.2 mA/V, plate resistance rp ≈ 1000.0 kΩ, max plate voltage 300 V, max plate dissipation 3 W, heater 6.3 V / 0.3 A.

Is the EF94 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the EF94 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 EF94 sound like?

European designation of the 6AU6 sharp-cutoff preamp/IF pentode.. 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

←EF94

← EF86 EFL200-Power →Compare → 6AU6

EF94 EF94 / 6AU6 Pentode Vacuum Tube

Pentode6.3V / 0.3A7-pin MiniatureSPICE

SourceMullard EF94 / RCA 6AU6 datasheetReviewed2026-05-29StatusDataModelCalcModelKoren pentodePDF

Small-signal pentode for low-noise voltage amplification

Datasheet ↗SPICE

EF94 / 6AU6 — Philips·Mullard — pentode vacuum tube — (1950)

1000.0kΩ

5.2mA/V

5.5pF

0.0pF

5.00pF

GAIN0%

POWER8%

DRIVE0%

LINEARITY75%

SPECIFICATIONS

Heater6.3 V · 0.3 A

Max Plate Voltage300 V

Pa max3 W

Gain Factor—

gm5.2 mA/V

rp1000.0 kΩ

Inter-electrode capacitances

Cgk5.5 pF

Cgp0.0035 pF

Cpk5 pF

Pinout7-pin Miniature

Era1950

RarityCommon

HEATER6.3V / 0.3A

MAX PLATE300V / 3W

BASEminiature-7

Source datasheets

1 manufacturer datasheets cross-checked for EF94 / 6AU6

1 verified

EXECUTIVE SUMMARY

The EF94 is a indirectly-heated pentode from Philips·Mullard, introduced around 1950. Commonly used in preamp / if amp applications. European designation of the 6AU6 sharp-cutoff preamp/IF pentode.

APPLICATIONS

Voltage amplifier

Generic pentode preamp / if amp stage

VS 6AU6

Rp +0%Pd 0%Full comparison →

HISTORY

Introduced1950ManufacturerPhilips·Mullard

Golden Age

EF94 Datasheet

Local mirror · PDF

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METRIX TESTER

Test this tube on a Metrix

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