What is the 7591 vacuum tube?

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

What is a 7591 substitute or equivalent?

Direct equivalents to the 7591 include None. 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 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.

By Jean-Michel Falligan Devergne · Reviewed May 29, 2026

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7591 7591A Tetrode Vacuum Tube

Tetrode6.3V / 0.8AOctalSPICE

SourceGE·SylvaniaReviewed2026-05-29StatusDataModelCalcModelKoren pentodePDF

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

Datasheet ↗SPICE

7591A — GE·Sylvania — tetrode vacuum tube — (1958)

29.0kΩ

10.2mA/V

10.0pF

0.3pF

5.00pF

GAIN17%

POWER48%

DRIVE71%

LINEARITY92%

SPECIFICATIONS

Heater6.3 V · 0.8 A

Max Plate Voltage550 V

Pa max19 W

Gain Factor17

gm10.2 mA/V

rp29.0 kΩ

Inter-electrode capacitances

Cgk10 pF

Cgp0.25 pF

Cpk5 pF

PinoutOctal

Era1958

RaritySought-after

HEATER6.3V / 0.8A

MAX PLATE550V / 19W

BASEoctal

Source datasheets

2 manufacturer datasheets cross-checked for 7591A

2 verified

EXECUTIVE SUMMARY

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.

APPLICATIONS

High-power output

Generic tetrode power (pp) stage

HISTORY

Introduced1958ManufacturerGE·Sylvania

Golden Age

7591 Datasheet

Local mirror · PDF

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METRIX TESTER

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