What is the 310A vacuum tube?

The 310A is a pentode vacuum tube designed for preamp applications. WE voltage pentode. Heart of the WE91A..

What is a 310A substitute or equivalent?

Direct equivalents to the 310A include 310B, 348A. 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 310A?

Amplification factor μ ≈ 1200, transconductance gm ≈ 1.8 mA/V, plate resistance rp ≈ 650.0 kΩ, max plate voltage 275 V, max plate dissipation 3.5 W, heater 10 V / 0.32 A.

Is the 310A still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 310A as Legendary 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 310A sound like?

WE voltage pentode. Heart of the WE91A.. 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 9, 2026

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310A Pentode Vacuum Tube

Pentode10V / 0.32ASpecial

SourceWestern Electric 310A datasheet (Smithsonian + WE squarespace)Reviewed2026-05-09StatusDataModelCalcModelunder reviewPDF

Small-signal pentode for low-noise voltage amplification

Datasheet ↗

310A — Western Electric — pentode vacuum tube — (1937)

1200

650.0kΩ

1.8mA/V

4.2pF

3.0pF

2.50pF

GAIN100%

POWER9%

DRIVE0%

LINEARITY10%

SPECIFICATIONS

Heater10 V · 0.32 A

Max Plate Voltage275 V

Pa max3.5 W

Gain Factor1200

gm1.8 mA/V

rp650.0 kΩ

Inter-electrode capacitances

Cgk4.2 pF

Cgp3 pF

Cpk2.5 pF

PinoutSpecial

Era1937

RarityLegendary

HEATER10V / 0.32A

MAX PLATE275V / 3.5W

BASEspecial

EXECUTIVE SUMMARY

The 310A is a indirectly-heated pentode from Western Electric, introduced around 1937. It provides a gain factor (μ) of 1200 with 650.0kΩ plate resistance. Commonly used in preamp applications. WE voltage pentode. Heart of the WE91A.

APPLICATIONS

Voltage amplifier

Generic pentode preamp stage

HISTORY

Introduced1937ManufacturerWestern Electric

Pre-War

310A Datasheet

Frank's Electron Tube Pages · PDF

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METRIX TESTER

Test this tube on a Metrix

SPICE model not yet available. Loadline calculator requires calibrated Koren parameters.

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