What is a 6SN7GTB substitute or equivalent?

Direct equivalents to the 6SN7GTB include 6SN7GTA (electrically identical, GTA lacks controlled warm-up) · 6SN7GT (downrated, 300V/5W only). 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 6SN7GTB?

Amplification factor μ ≈ 20, transconductance gm ≈ 2.6 mA/V, plate resistance rp ≈ 7.7 kΩ, max plate voltage 450 V, max plate dissipation 5 W, heater 6.3 V / 0.6 A.

Is the 6SN7GTB still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6SN7GTB 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 6SN7GTB sound like?

Late-1950s revision of the GTA adding a controlled-warm-up heater for series-string TV B+ chains. Audio behaviour identical to GTA: 450 V / 7.5 W total. The most-common production 6SN7 from the late 1950s through the 1980s.. 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.

6SN7GTB Triode Vacuum Tube

Q: What is the 6SN7GTB vacuum tube?

The 6SN7GTB is a triode vacuum tube designed for preamp / driver / phase inverter applications. Late-1950s revision of the GTA adding a controlled-warm-up heater for series-string TV B+ chains. Audio behaviour identical to GTA: 450 V / 7.5 W total. The most-common production 6SN7 from the late 1950s through the 1980s..

Also known as 6SN7GTA (electrically identical · GTA lacks controlled warm-up) · 6SN7GT (downrated · 300V · 5W only)

Medium-gain triode for driver and line stage applications

Dual triodeHeater 6.3 V · 0.6 AOctal2 sectionsRCA·Sylvania·GE·Tung-Sol 1958

Plate dissipation: 5W
Max plate voltage: 450V
Transconductance: 2.6mA/V

6SN7GTB

Characteristics

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

HeaterIndirectly heated

Specifications of 6SN7GTB — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.6 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6SN7GTB — Limiting values
Plate voltageVa max	450 V
Plate dissipationPa max	5 W

Mechanical

Specifications of 6SN7GTB — Mechanical
Base	Octal
Rarity	Common
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6SN7GTB — Small signal
Transconductance	2.6 mA/V
Plate resistance	7.7 kΩ
Amplification factor	20

Capacitances

Specifications of 6SN7GTB — Capacitances
Grid–cathode	2.2 pF
Grid–plate	4 pF
Plate–cathode	0.7 pF

Charactereditorial reading, not a measurement

Specifications of 6SN7GTB — Character
Gain	20%
Power	13%
Drive	92%
Linearity	90%

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

Using this tube

Applications

Push-pull output
Voltage amplifier
Phase splitter

Generic triode preamp / driver / phase inverter stage

Hi-Fi stereoHeadphone amp

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : RCA RC-26 (1968)Active model : Ayumi Nakabayashi · 2 engines

Manufacturer datasheets

4 manufacturer datasheets cross-checked for 6SN7GTB4 verified

6SN7GTB DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: RCA RC-26 (1968)
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Ayumi Nakabayashi · 2 engines

Context

The 6SN7GTB is a dual indirectly-heated triode from RCA·Sylvania·GE·Tung-Sol, introduced around 1958. It provides a gain factor (μ) of 20 with 7700Ω plate resistance. Commonly used in preamp / driver / phase inverter applications. Late-1950s revision of the GTA adding a controlled-warm-up heater for series-string TV B+ chains. Audio behaviour identical to GTA: 450 V / 7.5 W total. The most-common production 6SN7 from the late 1950s through the 1980s.

History

Introduced: 1958
Manufacturer: RCA·Sylvania·GE·Tung-Sol
Era: Golden Age

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