What is the E55L vacuum tube?

The E55L (E55L / 8233) is a pentode vacuum tube designed for power / driver applications. Extreme Gm pentode. Legendary..

What is a E55L substitute or equivalent?

Direct equivalents to the E55L include 8233, CV5808. 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 E55L?

Amplification factor μ ≈ 30, transconductance gm ≈ 45 mA/V, plate resistance rp ≈ 20.0 kΩ, max plate voltage 200 V, max plate dissipation 10 W, heater 6.3 V / 0.6 A.

Is the E55L still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the E55L 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 E55L sound like?

Extreme Gm pentode. Legendary.. 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.

E55L 8233 Pentode Vacuum Tube

Also known as 8233

Power pentode delivering up to 10W in pentode, UL, or triode mode

PentodeHeater 6.3 V · 0.6 A9-pin NovalPhilips 1958

Plate dissipation: 10W
Max plate voltage: 200V
Max screen voltage: 175V
Max cathode current: 75mA
Transconductance: 45mA/V

E55L

Characteristics

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

HeaterIndirectly heated

Specifications of E55L — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.6 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of E55L — Limiting values
Plate voltageVa max	200 V
Screen voltageVg2 max	175 V
Plate dissipationPa max	10 W
Cathode currentIk max	75 mA
Peak plate voltageVao	400 V

Mechanical

Specifications of E55L — Mechanical
Base	9-pin Noval
Rarity	Sought-after
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of E55L — Small signal
Transconductance	45 mA/V
Plate resistance	20 kΩ
Amplification factor	30

Capacitances

Specifications of E55L — Capacitances
Input	18 pF
Grid–plate	0.11 pF
Output	4 pF

Charactereditorial reading, not a measurement

Specifications of E55L — Character
Gain	30%
Power	25%
Drive	80%
Linearity	85%

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

Typical operation

Conditions published by the manufacturers, one row per condition. Nothing is computed.

Typical operation
Setup	Va	Vg1 / Rk	Ia	Ig2	gm	μ	Source
triode connection, single-endedclass not stated · fixed bias	125 V	-3 V	55.5 mA	5.5 mA	50 mA/V	5	read on the sheet Philips · 1961 · transcript

Using this tube

Applications

Power output

Generic pentode power / driver stage

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : Philips E55L/8233 datasheetActive model : Koren pentode

Manufacturer datasheets

3 manufacturer datasheets cross-checked for E55L / 82333 verified

Triode-connectedPhilips10.10.1961 (7Z2 series; Tentative data)

Va: 125 V
Vg1: -3 V
Ia: 55.5 mA
gm: 50 mA/V
µ: 45

E55L DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Philips E55L/8233 datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Koren pentode

Context

The E55L is a indirectly-heated pentode from Philips, introduced around 1958. It provides a gain factor (μ) of 30 with 20.0kΩ plate resistance. Commonly used in power / driver applications. Extreme Gm pentode. Legendary.

History

Introduced: 1958
Manufacturer: Philips
Era: Golden Age

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