What is the EL11 vacuum tube?

The EL11 is a pentode vacuum tube designed for power (se) applications. Side-contact Stahlroehre. Warm, rich..

What is a EL11 substitute or equivalent?

Direct equivalents to the EL11 include None direct. 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 EL11?

Amplification factor μ ≈ 25, 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 EL11 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the EL11 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 EL11 sound like?

Side-contact Stahlroehre. Warm, rich.. 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

←EL11

← EFL200-Pre EL12 →Compare…

EL11 Pentode Vacuum Tube

Pentode6.3V / 0.9A8-pin Side Contact Y8A

SourceTelefunken·PhilipsReviewed2026-05-29StatusDataModelCalcModelunder reviewPDF

Small-signal pentode for low-noise voltage amplification

Datasheet ↗

EL11 — Telefunken·Philips — pentode vacuum tube — (1938)

50.0kΩ

9.0mA/V

10.0pF

0.8pF

8.00pF

GAIN25%

POWER23%

DRIVE50%

LINEARITY88%

SPECIFICATIONS

Heater6.3 V · 0.9 A

Max Plate Voltage250 V

Pa max9 W

Gain Factor25

gm9 mA/V

rp50.0 kΩ

Inter-electrode capacitances

Cgk10 pF

Cgp0.8 pF

Cpk8 pF

Pinout8-pin Side Contact Y8A

Era1938

RaritySought-after

HEATER6.3V / 0.9A

MAX PLATE250V / 9W

BASEspecial

Source datasheets

3 manufacturer datasheets cross-checked for EL11

3 verified

EXECUTIVE SUMMARY

The EL11 is a indirectly-heated pentode from Telefunken·Philips, introduced around 1938. It provides a gain factor (μ) of 25 with 50.0kΩ plate resistance. Commonly used in power (se) applications. Side-contact Stahlroehre. Warm, rich.

HISTORY

Introduced1938ManufacturerTelefunken·Philips

Pre-War

EL11 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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