What is the EF806S vacuum tube?

The EF806S is a pentode vacuum tube designed for preamp applications. Special quality EF86. Ultra-low noise..

What is a EF806S substitute or equivalent?

Direct equivalents to the EF806S include EF86, 6267. 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 EF806S?

Amplification factor μ ≈ 38, transconductance gm ≈ 2 mA/V, plate resistance rp ≈ 2500.0 kΩ, max plate voltage 300 V, max plate dissipation 1 W, heater 6.3 V / 0.2 A.

Is the EF806S still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the EF806S as Sought-after 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 EF806S sound like?

Special quality EF86. Ultra-low noise.. 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.

EF806S Pentode Vacuum Tube

Also known as EF86 · 6267

Small-signal pentode for low-noise voltage amplification

PentodeHeater 6.3 V · 0.2 A9-pin NovalTelefunken 1955

Plate dissipation: 1W
Max plate voltage: 300V
Amplification factor: 38
Transconductance: 2mA/V
Plate resistance: 2.5MΩ

EF806S

Characteristics

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

HeaterIndirectly heated

Specifications of EF806S — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.2 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of EF806S — Limiting values
Plate voltageVa max	300 V
Screen voltageVg2 max	200 V
Plate dissipationPa max	1 W
Screen dissipationPg2 max	0.2 W
Cathode currentIk max	6 mA
Peak plate voltageVao	550 V
Heater–cathode voltageVhk max	100 V

Mechanical

Specifications of EF806S — Mechanical
Base	9-pin Noval
Rarity	Sought-after
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of EF806S — Small signal
Transconductance	2 mA/V
Plate resistance	2.5 MΩ
Amplification factor	38

Capacitances

Specifications of EF806S — Capacitances
Input	4 pF
Grid–plate	0.05 pF
Output	5.5 pF

Charactereditorial reading, not a measurement

Specifications of EF806S — Character
Gain	38%
Power	3%
Drive	0%
Linearity	81%

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 stage

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026

Manufacturer datasheets

3 manufacturer datasheets cross-checked for EF806S3 verified

EF806S DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

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

Context

The EF806S is a indirectly-heated pentode from Telefunken, introduced around 1955. It provides a gain factor (μ) of 38 with 2500.0kΩ plate resistance. Commonly used in preamp applications. Special quality EF86. Ultra-low noise.

History

Introduced: 1955
Manufacturer: Telefunken
Era: Golden Age

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