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.

EF800 Pentode Vacuum Tube

Also known as EF860 · CV5092

Small-signal pentode for low-noise voltage amplification

PentodeHeater 6.3 V · 0.295 A9-pin NovalTelefunken 1956

Plate dissipation: 1.7W
Max plate voltage: 250V
Amplification factor: 50
Transconductance: 7.5mA/V
Plate resistance: 400kΩ

EF800

Characteristics

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

HeaterIndirectly heated

Specifications of EF800 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.295 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of EF800 — Limiting values
Plate voltageVa max	250 V
Screen voltageVg2 max	250 V
Plate dissipationPa max	1.7 W
Screen dissipationPg2 max	0.7 W
Cathode currentIk max	12.5 mA
Peak plate voltageVao	550 V

Mechanical

Specifications of EF800 — Mechanical
Base	9-pin Noval
Rarity	Rare
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of EF800 — Small signal
Transconductance	7.5 mA/V
Plate resistance	400 kΩ
Amplification factor	50

Capacitances

Specifications of EF800 — Capacitances
Input	8.1 pF
Grid–plate	0.007 pF
Output	3.5 pF

Charactereditorial reading, not a measurement

Specifications of EF800 — Character
Gain	50%
Power	4%
Drive	0%
Linearity	75%

datasheet cited · model or editorial reading · catalogue value, no citation attached yet · nothing invented

Using this tube

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

Applications

Voltage amplifier

Generic pentode preamp / microphone stage

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026

Manufacturer datasheets

3 manufacturer datasheets cross-checked for EF8003 verified

EF800 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Telefunken
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

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.

History

Introduced: 1956
Manufacturer: Telefunken
Era: Golden Age

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