What is the 6350 vacuum tube?

The 6350 is a triode vacuum tube designed for preamp applications. IBM computer tube. 12AU7 cousin, tighter spec..

What are the key specifications of the 6350?

Amplification factor μ ≈ 18, transconductance gm ≈ 4.6 mA/V, plate resistance rp ≈ 3.9 kΩ, max plate voltage 330 V, max plate dissipation 4 W, heater 6.3 V / 0.6 A.

Is the 6350 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6350 as Moderate 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 6350 sound like?

IBM computer tube. 12AU7 cousin, tighter spec.. 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.

6350 Triode Vacuum Tube

Medium-gain triode for driver and line stage applications

Dual triodeHeater 6.3 V · 0.6 A9-pin Noval2 sectionsGE·RCA 1957

Plate dissipation: 4W
Max plate voltage: 330V
Amplification factor: 18
Transconductance: 4.6mA/V
Plate resistance: 3.9kΩ

6350

Characteristics

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

HeaterIndirectly heated

Specifications of 6350 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.6 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6350 — Limiting values
Plate voltageVa max	330 V
Plate dissipationPa max	4 W

Mechanical

Specifications of 6350 — Mechanical
Base	9-pin Noval
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6350 — Small signal
Transconductance	4.6 mA/V
Plate resistance	3.9 kΩ
Amplification factor	18

Capacitances

Specifications of 6350 — Capacitances
Grid–cathode	3.6 pF
Grid–plate	3.2 pF
Plate–cathode	0.6 pF

Charactereditorial reading, not a measurement

Specifications of 6350 — Character
Gain	18%
Power	10%
Drive	96%
Linearity	91%

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

Typical operation

Canonical operating pointModel

B+: 275 V
Load: 8 kΩ
Va: 165 V
Ia: 9.87 mA
Vg: -6 V
Pd: 1.63 W
Gain: 21.2 dB

At Q: Ayumi Nakabayashi
μ: 19.6
gm: 4.34 mA/V
rp: 4.5 kΩ

Using this tube

Applications

Voltage amplifier
Line stage
Phase splitter

Generic triode preamp 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 63504 verified

6350 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

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

Context

The 6350 is a dual indirectly-heated triode from GE·RCA, introduced around 1957. It provides a gain factor (μ) of 18 with 3900Ω plate resistance. Commonly used in preamp applications. IBM computer tube. 12AU7 cousin, tighter spec.

History

Introduced: 1957
Manufacturer: GE·RCA
Era: Golden Age

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