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.

310A Pentode Vacuum Tube

Also known as 310B · 348A

Small-signal pentode for low-noise voltage amplification

PentodeHeater 10 V · 0.32 ASpecialWestern Electric 1937

Plate dissipation: 3.5W
Max plate voltage: 275V
Amplification factor: 1200
Transconductance: 1.8mA/V
Plate resistance: 650kΩ

310A

Characteristics

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

HeaterIndirectly heated

Specifications of 310A — Heater
Heater voltageVh	10 V
Heater currentIh	0.32 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 310A — Limiting values
Plate voltageVa max	275 V
Plate dissipationPa max	3.5 W

Mechanical

Specifications of 310A — Mechanical
Base	Special
Rarity	Legendary
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 310A — Small signal
Transconductance	1.8 mA/V
Plate resistance	650 kΩ
Amplification factor	1200

Capacitances

Specifications of 310A — Capacitances
Input	4.2 pF
Grid–plate	3 pF
Output	2.5 pF

Charactereditorial reading, not a measurement

Specifications of 310A — Character
Gain	100%
Power	9%
Drive	0%
Linearity	10%

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

Using this tube

No interactive loadline model for this tube yet — download a SPICE model below to simulate it in LTspice or ngspice.

Applications

Voltage amplifier

Generic pentode preamp stage

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 9, 2026Source : Western Electric 310A datasheet (Smithsonian + WE squarespace)

Manufacturer datasheets

310A DatasheetFrank's Electron Tube Pages · PDF

SPICE models

Revision and verification status

Source: Western Electric 310A datasheet (Smithsonian + WE squarespace)
Reviewed: 2026-05-09
Status: DataModelCalc
Model: under review

Context

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.

History

Introduced: 1937
Manufacturer: Western Electric
Era: Pre-War

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