What is the 5881 vacuum tube?

The 5881 (5881 / 6L6WGB) is a tetrode vacuum tube designed for power (pp) applications. Ruggedized 6L6..

What is a 5881 substitute or equivalent?

Direct equivalents to the 5881 include 6L6 family (6L6WGB / 5881 mil-spec) — NOT a universal 6L6GC drop-in; 5881 rated 23W vs 6L6GC 30W; verify screen voltage and bias before substitution. 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 5881?

Amplification factor μ ≈ 8, transconductance gm ≈ 6.1 mA/V, plate resistance rp ≈ 30.0 kΩ, max plate voltage 400 V, max plate dissipation 23 W, heater 6.3 V / 0.9 A.

Is the 5881 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 5881 as Common 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 5881 sound like?

Ruggedized 6L6.. 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.

5881 6L6WGB Tetrode Vacuum Tube

Also known as 6L6 family (6L6WGB · 5881 mil-spec) — NOT a universal 6L6GC drop-in · 5881 rated 23W vs 6L6GC 30W · verify screen voltage and bias before substitution

Beam power tetrode rated at 23W for high-power output stages

TetrodeHeater 6.3 V · 0.9 AOctalTung-Sol 1952

Plate dissipation: 23W
Max plate voltage: 400V
Transconductance: 6.1mA/V

5881

Characteristics

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

HeaterIndirectly heated

Specifications of 5881 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.9 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 5881 — Limiting values
Plate voltageVa max	400 V
Plate dissipationPa max	23 W

Mechanical

Specifications of 5881 — Mechanical
Base	Octal
Rarity	Common
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 5881 — Small signal
Transconductance	6.1 mA/V
Plate resistance	30 kΩ
Amplification factor	8

Capacitances

Specifications of 5881 — Capacitances
Input	10 pF
Grid–plate	0.9 pF
Output	12 pF

Charactereditorial reading, not a measurement

Specifications of 5881 — Character
Gain	8%
Power	57%
Drive	70%
Linearity	95%

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	Vg2	Vg1 / Rk	Ia	Ig2	Load	Pout	THD	gm	rp	Source
Class A, single-endedpentode connection · fixed bias	250 V	250 V	-14 V	75 mA	4.3 mA	2.5 kΩ	6.7 W	10%	6.1 mA/V	30 kΩ	OCR, to be checked RCA · 1957 · p. 1 · transcript
Class A, single-endedtriode connection · fixed bias	250 V		-14 V	75 mA	4.3 mA	2.5 kΩ	6.7 W	10%	6.1 mA/V	30 kΩ	OCR, to be checked Tung-Sol Electric Inc. · 1962 · p. 1 · transcript

Using this tube

Applications

High-power output

Fender BassmanLeslie 122 speaker cabinet

Guitar amp

Featured in these amplifiers

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : Tung-Sol 5881 datasheetActive model : Koren v1

Manufacturer datasheets

2 manufacturer datasheets cross-checked for 5881 / 6L6WGB2 verified

5881 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Tung-Sol 5881 datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Koren v1

Context

The 5881 is the military ruggedized version of the 6L6, with a lower plate dissipation rating (23W versus 30W for the 6L6GC) but enhanced vibration resistance and reliability. Sonically it sits between the 6V6 and 6L6GC in character, with a slightly warmer, more compressed sound than a full 6L6GC that many find appealing for both guitar and hi-fi applications. The reduced plate dissipation means it runs cooler and typically lasts longer in circuits designed within its ratings. Tung-Sol and Sylvania manufactured the bulk of NOS production; the 5881 is a popular choice in amplifiers like the Fender Bassman where it offers a different flavor from the stock 6L6GC.

History

Introduced: 1952
Manufacturer: Tung-Sol
Era: Golden Age

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