What is the EF800 vacuum tube?

The EF800 is a pentode vacuum tube designed for preamp / microphone applications. Professional Telefunken pentode. Neumann mic tube..

What is a EF800 substitute or equivalent?

Direct equivalents to the EF800 include EF860, CV5092. 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 EF800?

Amplification factor μ ≈ 50, transconductance gm ≈ 7.5 mA/V, plate resistance rp ≈ 400.0 kΩ, max plate voltage 250 V, max plate dissipation 1.7 W, heater 6.3 V / 0.295 A.

Is the EF800 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the EF800 as Rare 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 EF800 sound like?

Professional Telefunken pentode. Neumann mic tube.. 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

←EF800

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EF800 Pentode Vacuum Tube

Pentode6.3V / 0.295A9-pin Noval

SourceTelefunkenReviewed2026-05-29StatusDataModelCalcModelunder reviewPDF

Small-signal pentode for low-noise voltage amplification

Datasheet ↗

EF800 — Telefunken — pentode vacuum tube — (1956)

400.0kΩ

7.5mA/V

8.1pF

0.0pF

3.50pF

GAIN50%

POWER4%

DRIVE0%

LINEARITY75%

SPECIFICATIONS

Heater6.3 V · 0.295 A

Max Plate Voltage250 V

Pa max1.7 W

Gain Factor50

gm7.5 mA/V

rp400.0 kΩ

Inter-electrode capacitances

Cgk8.1 pF

Cgp0.007 pF

Cpk3.5 pF

Pinout9-pin Noval

Era1956

RarityRare

HEATER6.3V / 0.295A

MAX PLATE250V / 1.7W

BASEnoval

Source datasheets

3 manufacturer datasheets cross-checked for EF800

3 verified

EXECUTIVE SUMMARY

The EF800 is a indirectly-heated pentode from Telefunken, introduced around 1956. It provides a gain factor (μ) of 50 with 400.0kΩ plate resistance. Commonly used in preamp / microphone applications. Professional Telefunken pentode. Neumann mic tube.

APPLICATIONS

Voltage amplifier

Generic pentode preamp / microphone stage

HISTORY

Introduced1956ManufacturerTelefunken

Golden Age

EF800 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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