What is the EL91 vacuum tube?

The EL91 is a pentode vacuum tube designed for power applications. Small audio output..

What is a EL91 substitute or equivalent?

Direct equivalents to the EL91 include 6AM5. 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 EL91?

Amplification factor μ ≈ 12, transconductance gm ≈ 2.6 mA/V, plate resistance rp ≈ 130.0 kΩ, max plate voltage 250 V, max plate dissipation 4 W, heater 6.3 V / 0.2 A.

Is the EL91 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the EL91 as Moderate 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 EL91 sound like?

Small audio output.. 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.

EL91 Pentode Vacuum Tube

Also known as 6AM5

Small-signal pentode for low-noise voltage amplification

PentodeHeater 6.3 V · 0.2 A7-pin MiniaturePhilips 1950

Plate dissipation: 4W
Max plate voltage: 250V
Amplification factor: 12
Transconductance: 2.6mA/V
Plate resistance: 130kΩ

EL91

Characteristics

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

HeaterIndirectly heated

Specifications of EL91 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.2 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of EL91 — Limiting values
Plate voltageVa max	250 V
Screen voltageVg2 max	250 V
Plate dissipationPa max	4 W
Cathode currentIk max	25 mA
Grid resistorRg1 max	700 kΩ

Mechanical

Specifications of EL91 — Mechanical
Base	7-pin Miniature
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of EL91 — Small signal
Transconductance	2.6 mA/V
Plate resistance	130 kΩ
Amplification factor	12

Capacitances

Specifications of EL91 — Capacitances
Input	4 pF
Grid–plate	0.3 pF
Output	3.75 pF

Charactereditorial reading, not a measurement

Specifications of EL91 — Character
Gain	12%
Power	10%
Drive	0%
Linearity	94%

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 power stage

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : audit-eu_b (CLEAN — matches canonical datasheet)

Manufacturer datasheets

4 manufacturer datasheets cross-checked for EL914 verified

Triode-connectedMullard1962 (MAY 1962)

Va: 250 V
Vg1: -13.5 V
Ia: 18.3 mA
gm: 2.7 mA/V
µ: 12
Ra: 18 Ω
Pout: 1.7 W

EL91 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: audit-eu_b (CLEAN — matches canonical datasheet)
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The EL91 is a indirectly-heated pentode from Philips, introduced around 1950. It provides a gain factor (μ) of 12 with 130.0kΩ plate resistance. Commonly used in power applications. Small audio output.

History

Introduced: 1950
Manufacturer: Philips
Era: Golden Age

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