What is the 46 vacuum tube?

The 46 is a triode vacuum tube designed for power (set) applications. Dual-grid power tube. 45 cousin in triode mode..

What are the key specifications of the 46?

Amplification factor μ ≈ 6, transconductance gm ≈ 2.35 mA/V, plate resistance rp ≈ 2.4 kΩ, max plate voltage 400 V, max plate dissipation 10 W, heater 2.5 V / 1.75 A.

Is the 46 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 46 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 46 sound like?

Dual-grid power tube. 45 cousin in triode mode.. 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.

46 Triode Vacuum Tube

Power triode delivering 10W for push-pull and SET designs

TriodeHeater 2.5 V · 1.75 AUX-5RCA·Sylvania 1931

Plate dissipation: 10W
Max plate voltage: 400V
Transconductance: 2.35mA/V

Characteristics

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

HeaterDirectly heated

Specifications of 46 — Heater
Heater voltageVh	2.5 V
Heater currentIh	1.75 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 46 — Limiting values
Plate voltageVa max	400 V
Plate dissipationPa max	10 W

Mechanical

Specifications of 46 — Mechanical
Base	UX-5
Rarity	Sought-after
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 46 — Small signal
Transconductance	2.35 mA/V
Plate resistance	2.4 kΩ
Amplification factor	6

Capacitances

Specifications of 46 — Capacitances
Grid–cathode	7 pF
Grid–plate	7.5 pF
Plate–cathode	4.5 pF

Charactereditorial reading, not a measurement

Specifications of 46 — Character
Gain	6%
Power	25%
Drive	98%
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	Vg1 / Rk	Ia	Load	gm	μ	rp	Source
Class A, single-endedtriode connection	250 V		22 mA	6.4 kΩ	2.35 mA/V	5.6	2.4 kΩ	OCR, to be checked Tung-Sol · 1939 · p. 1 · transcript
Class B, push-pulltriode connection · fixed bias	300 V	0 V	8 mA	5.2 kΩ a-a				OCR, to be checked RCA · n/d · p. 1 · transcript

Using this tube

Applications

SET output
Push-pull output

Generic triode power (set) stage

Hi-Fi stereoHeadphone amp

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Active model : Ayumi Nakabayashi

Manufacturer datasheets

4 manufacturer datasheets cross-checked for 464 verified

46 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: RCA·Sylvania
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Ayumi Nakabayashi

Context

The 46 is a directly-heated triode from RCA·Sylvania, introduced around 1931. It provides a gain factor (μ) of 6 with 2380Ω plate resistance. Commonly used in power (set) applications. Dual-grid power tube. 45 cousin in triode mode.

History

Introduced: 1931
Manufacturer: RCA·Sylvania
Era: Pre-War

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