What is the 6SN7 vacuum tube?

The 6SN7 (6SN7GT) is a triode vacuum tube designed for preamp / driver applications. Original 1939 RCA dual triode. Max plate voltage 300 V, total dissipation 5 W (2.5 W per section) — DO NOT substitute into amplifiers designed for 6SN7GTA/GTB ratings (450 V / 7.5 W) without de-rating, you will destroy the tube. Same μ/gm/rp as later variants; sonic 'legend' status driven by NOS Sylvania, RCA grey-glass and Tung-Sol round-plate examples..

What is a 6SN7 substitute or equivalent?

Direct equivalents to the 6SN7 include 6SN7GTA / 6SN7GTB (uprated, NOT interchangeable in modern designs that exceed 300V/5W) · CV1988 · 6H8C (Soviet, ≈GT-rated). 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 6SN7?

Amplification factor μ ≈ 20, transconductance gm ≈ 2.6 mA/V, plate resistance rp ≈ 7.7 kΩ, max plate voltage 300 V, max plate dissipation 2.5 W, heater 6.3 V / 0.6 A.

Is the 6SN7 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6SN7 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 6SN7 sound like?

Original 1939 RCA dual triode. Max plate voltage 300 V, total dissipation 5 W (2.5 W per section) — DO NOT substitute into amplifiers designed for 6SN7GTA/GTB ratings (450 V / 7.5 W) without de-rating, you will destroy the tube. Same μ/gm/rp as later variants; sonic 'legend' status driven by NOS Sylvania, RCA grey-glass and Tung-Sol round-plate examples.. 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.

6SN7 GT Triode Vacuum Tube

Also known as 6SN7GTA · 6SN7GTB (uprated · NOT interchangeable in modern designs that exceed 300V · 5W) · CV1988 · 6H8C (Soviet · ≈GT-rated)

Medium-gain triode for driver and line stage applications

Dual triodeHeater 6.3 V · 0.6 AOctal2 sectionsSylvania·RCA·Tung-Sol 1939

Plate dissipation: 2.5W
Max plate voltage: 300V
Amplification factor: 20
Transconductance: 2.6mA/V
Plate resistance: 7.7kΩ

6SN7

Characteristics

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

HeaterIndirectly heated

Specifications of 6SN7 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.6 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6SN7 — Limiting values
Plate voltageVa max	300 V
Plate dissipationPa max	2.5 W
Cathode currentIk max	20 mA
Grid resistorRg1 max	1 MΩ
Heater–cathode voltageVhk max	100 V

Mechanical

Specifications of 6SN7 — Mechanical
Base	Octal
Rarity	Sought-after
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6SN7 — Small signal
Transconductance	2.6 mA/V
Plate resistance	7.7 kΩ
Amplification factor	20

Capacitances

Specifications of 6SN7 — Capacitances
Grid–cathode	2.2 pF
Grid–plate	4 pF
Plate–cathode	0.8 pF

Charactereditorial reading, not a measurement

Specifications of 6SN7 — Character
Gain	20%
Power	6%
Drive	92%
Linearity	90%

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

Typical operation

Canonical operating pointSPICE model2 availableModel

B+: 280 V
Load: 7.7 kΩ
Va: 168 V
Ia: 1.14 mA
Vg: -8 V
Pd: 0.19 W
Gain: 15.1 dB

At Q: Ayumi Nakabayashi · 2 engines
μ: 18.1
gm: 0.93 mA/V
rp: 19.4 kΩ

Design a stage →

Using this tube

Applications

Voltage amplifier
Phase splitter

Sylvania Type 122 preampCary SLP-05

Hi-Fi stereoHeadphone amp

Classic circuits

6SN7 Preamp Stage
Headphone Amp
Classic 6SN7 medium-mu triode as driver or headphone preamp. Renowned for its musicality and natural tonal balance.
SEVb 300V · Vg -8V · RL 10kΩSylvania 6SN7GT Datasheet
6AS7 OTL Headphone
Headphone Amp0.5W
6SN7-based OTL headphone amplifier. Medium-mu triode in cathode follower configuration driving headphones directly. Classic OTL topology.
SEVb 150V · Vg -56V · RL 300ΩRCA 6AS7G Datasheet / Bottlehead Crack
6SN7 Driver Stage
Preamp Stage
6SN7 as push-pull driver or line stage. Medium-mu octal triode beloved for its tonal character. Used in Cary, Supratek, and countless DIY designs.
SEVb 300V · Vg -8V · RL 20kΩSylvania 6SN7GT Datasheet

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Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : RCA RC-15 (1939) · Sylvania · Tung-SolActive model : Ayumi Nakabayashi · 2 engines

Manufacturer datasheets

1 manufacturer datasheets cross-checked for 6SN7GT1 verified

6SN7 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: RCA RC-15 (1939) · Sylvania · Tung-Sol
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Ayumi Nakabayashi · 2 engines

Context

The 6SN7 is a medium-mu (mu ~20) octal dual triode that many consider the finest-sounding small-signal tube ever made. Its separate cathode structure and generous physical size give it better linearity and lower distortion than the miniature 12AU7, which was designed as its noval replacement. The 6SN7 excels as a line stage, driver, and phase inverter, with a natural, open, dimensional sound quality that has made it the centerpiece of many reference preamp designs. Sylvania VT-231 (WWII era), Ken-Rad VT-231, and Tung-Sol round-plate variants are legendary among audiophiles, though Shuguang and Psvane produce credible current alternatives.

History

Introduced: 1939
Manufacturer: Sylvania·RCA·Tung-Sol
Era: Pre-War

METRIX TESTER

Characteristics

HeaterIndirectly heated

Limiting valuesDatasheet maximum ratings — not to be exceeded

Mechanical

Small signalDatasheet parameters at the reference operating point — not limits

Capacitances

Charactereditorial reading, not a measurement?

Typical operation

Using this tube

Applications

Classic circuits

6SN7 Preamp Stage

6AS7 OTL Headphone

6SN7 Driver Stage

Replace or compare

Direct equivalents

Versus 6SL7

Comparisons

Similar tubes