What is the 6GU7 vacuum tube?

The 6GU7 is a triode vacuum tube designed for preamp applications. Clean driver..

What are the key specifications of the 6GU7?

Amplification factor μ ≈ 17, transconductance gm ≈ 3.1 mA/V, plate resistance rp ≈ 5.5 kΩ, max plate voltage 330 V, max plate dissipation 3 W, heater 6.3 V / 0.6 A.

Is the 6GU7 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6GU7 as Common 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 6GU7 sound like?

Clean driver.. 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.

6GU7 Triode Vacuum Tube

Medium-gain triode for driver and line stage applications

Dual triodeHeater 6.3 V · 0.6 A9-pin Noval2 sectionsRCA·Sylvania 1960

Plate dissipation: 3W
Max plate voltage: 330V
Amplification factor: 17
Transconductance: 3.1mA/V
Plate resistance: 5.5kΩ

6GU7

Characteristics

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

HeaterIndirectly heated

Specifications of 6GU7 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.6 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6GU7 — Limiting values
Plate voltageVa max	330 V
Plate dissipationPa max	3 W

Mechanical

Specifications of 6GU7 — Mechanical
Base	9-pin Noval
Rarity	Common
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6GU7 — Small signal
Transconductance	3.1 mA/V
Plate resistance	5.5 kΩ
Amplification factor	17

Capacitances

Specifications of 6GU7 — Capacitances
Grid–cathode	3.4 pF
Grid–plate	3 pF
Plate–cathode	0.44 pF

Charactereditorial reading, not a measurement

Specifications of 6GU7 — Character
Gain	17%
Power	8%
Drive	95%
Linearity	92%

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

Typical operation

Canonical operating pointModel

B+: 275 V
Load: 11 kΩ
Va: 165 V
Ia: 6.9 mA
Vg: -7 V
Pd: 1.14 W
Gain: 24 dB

At Q: Norman Koren
μ: 18.5
gm: 2.86 mA/V
rp: 6.5 kΩ

Design a stage →

Using this tube

Applications

Voltage amplifier
Line stage
Phase splitter

Generic triode preamp stage

Hi-Fi stereoHeadphone amp

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Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : audit-us_a (CLEAN — matches canonical datasheet)Active model : Norman Koren

Manufacturer datasheets

3 manufacturer datasheets cross-checked for 6GU73 verified

6GU7 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: audit-us_a (CLEAN — matches canonical datasheet)
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Norman Koren

Context

The 6GU7 is a dual indirectly-heated triode from RCA·Sylvania, introduced around 1960. It provides a gain factor (μ) of 17 with 5500Ω plate resistance. Commonly used in preamp applications. Clean driver.

History

Introduced: 1960
Manufacturer: RCA·Sylvania
Era: Late Production

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