What is the 7591 vacuum tube?

The 7591 (7591A) is a tetrode vacuum tube designed for power (pp) applications. Fisher/Scott output classic..

What are the key specifications of the 7591?

Amplification factor μ ≈ 17, transconductance gm ≈ 10.2 mA/V, plate resistance rp ≈ 29.0 kΩ, max plate voltage 550 V, max plate dissipation 19 W, heater 6.3 V / 0.8 A.

Is the 7591 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 7591 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 7591 sound like?

Fisher/Scott output classic.. 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.

7591 A Tetrode Vacuum Tube

Beam power tetrode rated at 19W for high-power output stages

TetrodeHeater 6.3 V · 0.8 AOctalGE·Sylvania 1958

Plate dissipation: 19W
Max plate voltage: 550V
Transconductance: 10.2mA/V

7591

Characteristics

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

HeaterIndirectly heated

Specifications of 7591 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.8 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 7591 — Limiting values
Plate voltageVa max	550 V
Plate dissipationPa max	19 W

Mechanical

Specifications of 7591 — Mechanical
Base	Octal
Rarity	Sought-after
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 7591 — Small signal
Transconductance	10.2 mA/V
Plate resistance	29 kΩ
Amplification factor	17

Capacitances

Specifications of 7591 — Capacitances
Input	10 pF
Grid–plate	0.25 pF
Output	5 pF

Charactereditorial reading, not a measurement

Specifications of 7591 — Character
Gain	17%
Power	48%
Drive	71%
Linearity	92%

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

Using this tube

Applications

High-power output

Generic tetrode power (pp) stage

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Active model : Koren pentode

Manufacturer datasheets

2 manufacturer datasheets cross-checked for 7591A2 verified

7591 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: GE·Sylvania
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Koren pentode

Context

The 7591 is a indirectly-heated beam tetrode from GE·Sylvania, introduced around 1958. It provides a gain factor (μ) of 17 with 29.0kΩ plate resistance. Commonly used in power (pp) applications. Fisher/Scott output classic.

History

Introduced: 1958
Manufacturer: GE·Sylvania
Era: Golden Age

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