What is the 12AT7 vacuum tube?

The 12AT7 (12AT7 / ECC81) is a triode vacuum tube designed for driver applications. Detailed, articulate..

What is a 12AT7 substitute or equivalent?

Direct equivalents to the 12AT7 include ECC81, 6201. 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 12AT7?

Amplification factor μ ≈ 60, transconductance gm ≈ 5.5 mA/V, plate resistance rp ≈ 10.9 kΩ, max plate voltage 300 V, max plate dissipation 2.5 W, heater 12.6 V / 0.15 A.

Is the 12AT7 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 12AT7 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 12AT7 sound like?

Detailed, articulate.. 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.

12AT7 ECC81 Triode Vacuum Tube

Also known as ECC81

Medium-gain triode for voltage amplification applications

Dual triodeHeater 12.6 V · 0.15 A9-pin Noval2 sectionsMullard·GE 1947

Plate dissipation: 2.5W
Max plate voltage: 300V
Amplification factor: 60
Transconductance: 5.5mA/V
Plate resistance: 10.9kΩ

12AT7

Characteristics

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

HeaterIndirectly heated

Specifications of 12AT7 — Heater
Heater voltageVh	12.6 V
Heater currentIh	0.15 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 12AT7 — Limiting values
Plate voltageVa max	300 V
Plate dissipationPa max	2.5 W
Cathode currentIk max	15 mA
Peak plate voltageVao	550 V
Heater–cathode voltageVhk max	90 V

Mechanical

Specifications of 12AT7 — Mechanical
Base	9-pin Noval
Rarity	Common
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 12AT7 — Small signal
Transconductance	5.5 mA/V
Plate resistance	10.9 kΩ
Amplification factor	60

Capacitances

Specifications of 12AT7 — Capacitances
Grid–cathode	2.2 pF
Grid–plate	1.5 pF
Plate–cathode	0.5 pF

Charactereditorial reading, not a measurement

Specifications of 12AT7 — Character
Gain	60%
Power	6%
Drive	89%
Linearity	70%

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

Typical operation

Canonical operating pointSPICE model3 availableModel

B+: 300 V
Load: 10 kΩ
Va: 180 V
Ia: 3.73 mA
Vg: -2.2 V
Pd: 0.67 W
Gain: 28 dB

At Q: Ayumi Nakabayashi · 3 engines
μ: 56.6
gm: 3.29 mA/V
rp: 17.2 kΩ

Design a stage →

Using this tube

Applications

High-gain preamp
Phase splitter

Marshall JCM800 PIFender reverb driver

Guitar ampHeadphone ampStudio/recording

Featured in these amplifiers

Classic circuits

12AT7 Driver Stage
Preamp Stage
12AT7 as phase inverter or driver stage. Medium-mu triode with higher current capability than 12AX7. Common in Fender reverb drivers.
SEVb 250V · Vg -2V · RL 47kΩFender Reverb Driver Circuit

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : Mullard·GE datasheetActive model : Ayumi Nakabayashi · 3 engines

Manufacturer datasheets

11 manufacturer datasheets cross-checked for 12AT7 / ECC8111 verified

12AT7 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Mullard·GE datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Ayumi Nakabayashi · 3 engines

Context

The 12AT7 (ECC81) is a medium-mu (mu ~60) dual triode designed for VHF applications, with lower plate resistance (~11k ohms) and higher transconductance than the 12AX7. In audio it serves as a driver tube, phase inverter, or anywhere moderate gain with better current delivery is needed than a 12AX7 can provide. Its lower plate resistance makes it superior for driving capacitive loads and long interstage connections. The 12AT7 is also the standard reverb driver and effects loop tube in guitar amplifiers, where its current capability matters more than raw voltage gain.

History

Introduced: 1947
Manufacturer: Mullard·GE
Era: Golden Age

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