What is the 417A vacuum tube?

The 417A (417A / 5842) is a triode vacuum tube designed for phono / preamp applications. Same as 5842..

What is a 417A substitute or equivalent?

Direct equivalents to the 417A include 5842. 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 417A?

Amplification factor μ ≈ 43, transconductance gm ≈ 25 mA/V, plate resistance rp ≈ 1.7 kΩ, max plate voltage 200 V, max plate dissipation 4.5 W, heater 6.3 V / 0.3 A.

Is the 417A still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 417A as Collector 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 417A sound like?

Same as 5842.. 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.

417A 5842 Triode Vacuum Tube

Also known as 5842

Medium-gain triode for driver and line stage applications

TriodeHeater 6.3 V · 0.3 A9-pin NovalWestern Electric 1956

Plate dissipation: 4.5W
Max plate voltage: 200V
Amplification factor: 43
Transconductance: 25mA/V
Plate resistance: 1.7kΩ

417A

Characteristics

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

HeaterIndirectly heated

Specifications of 417A — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.3 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 417A — Limiting values
Plate voltageVa max	200 V
Plate dissipationPa max	4.5 W
Cathode currentIk max	38 mA
Heater–cathode voltageVhk max	55 V

Mechanical

Specifications of 417A — Mechanical
Base	9-pin Noval
Rarity	Collector
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 417A — Small signal
Transconductance	25 mA/V
Plate resistance	1.7 kΩ
Amplification factor	43

Capacitances

Specifications of 417A — Capacitances
Grid–cathode	9 pF
Grid–plate	1.8 pF
Plate–cathode	0.55 pF

Charactereditorial reading, not a measurement

Specifications of 417A — Character
Gain	43%
Power	11%
Drive	98%
Linearity	79%

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

Using this tube

Applications

Voltage amplifier
Headphone output
Phono stage

Generic triode phono / preamp stage

Hi-Fi stereoHeadphone amp

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Active model : Ayumi Nakabayashi · 2 engines

Manufacturer datasheets

8 manufacturer datasheets cross-checked for 417A / 58428 verified

417A DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Western Electric
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Ayumi Nakabayashi · 2 engines

Context

The 5842 (417A) is a Western Electric frame-grid triode designed for wideband amplifier and carrier telephone service, with extremely high transconductance (~25 mA/V) and a mu of ~43. It is one of the most linear small-signal triodes ever manufactured, with bandwidth extending well into the MHz range and distortion figures that rival solid-state devices. The tube demands careful layout due to its high transconductance and tendency toward oscillation if improperly decoupled. Genuine WE 417A/5842 examples are expensive but remain in reasonable supply from military surplus, and the tube rewards careful circuit design with exceptional transparency and resolution.

History

Introduced: 1956
Manufacturer: Western Electric
Era: Golden Age

METRIX TESTER