What is the 12AU7 vacuum tube?

The 12AU7 (12AU7 / ECC82) is a triode vacuum tube designed for line / headphone applications. Open, transparent, neutral..

What is a 12AU7 substitute or equivalent?

Direct equivalents to the 12AU7 include ECC82, 5814A. 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 12AU7?

Amplification factor μ ≈ 17, transconductance gm ≈ 2.2 mA/V, plate resistance rp ≈ 7.7 kΩ, max plate voltage 300 V, max plate dissipation 2.75 W, heater 12.6 V / 0.15 A.

Is the 12AU7 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 12AU7 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 12AU7 sound like?

Open, transparent, neutral.. 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.

12AU7 ECC82 Triode Vacuum Tube

Also known as ECC82 · 5814A

Medium-gain triode for driver and line stage applications

Dual triodeHeater 12.6 V · 0.15 A9-pin Noval2 sectionsRCA·Amperex 1946

Plate dissipation: 2.75W
Max plate voltage: 300V
Amplification factor: 17
Transconductance: 2.2mA/V
Plate resistance: 7.7kΩ

12AU7

Characteristics

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

HeaterIndirectly heated

Specifications of 12AU7 — Heater
Heater voltageVh	12.6 V
Heater currentIh	0.15 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 12AU7 — Limiting values
Plate voltageVa max	300 V
Plate dissipationPa max	2.75 W

Mechanical

Specifications of 12AU7 — Mechanical
Base	9-pin Noval
Rarity	Common
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 12AU7 — Small signal
Transconductance	2.2 mA/V
Plate resistance	7.7 kΩ
Amplification factor	17

Capacitances

Specifications of 12AU7 — Capacitances
Grid–cathode	1.7 pF
Grid–plate	1.5 pF
Plate–cathode	0.5 pF

Charactereditorial reading, not a measurement

Specifications of 12AU7 — Character
Gain	17%
Power	7%
Drive	92%
Linearity	92%

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

Typical operation

Canonical operating pointSPICE model2 availableModel

B+: 300 V
Load: 12 kΩ
Va: 180 V
Ia: 5.97 mA
Vg: -6.6 V
Pd: 1.07 W
Gain: 21.5 dB

At Q: Ayumi Nakabayashi · 2 engines
μ: 16.8
gm: 1.8 mA/V
rp: 9.3 kΩ

Design a stage →

Using this tube

Applications

Line stage
Phase splitter

McIntosh C22 line stageMarantz 8B driver

Guitar ampHeadphone amp

Featured in these amplifiers

Classic circuits

12AU7 Preamp Stage
Headphone Amp
Typical 12AU7 voltage amplifier stage for headphone buffer or line-level preamp. Moderate gain with low output impedance.
SEVb 250V · Vg -8.5V · RL 100kΩRCA 12AU7 Datasheet

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : RCA·Amperex datasheetActive model : Ayumi Nakabayashi · 2 engines

Manufacturer datasheets

2 manufacturer datasheets cross-checked for 12AU7 / ECC822 verified

12AU7 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: RCA·Amperex datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Ayumi Nakabayashi · 2 engines

Context

The 12AU7 (ECC82) is a low-mu (mu ~17) dual triode with the lowest gain and lowest plate resistance of the 12A_7 family. Its strong suit is current delivery and linearity rather than voltage gain, making it the preferred tube for cathode followers, buffers, headphone amplifiers, and line output stages. The low mu and low plate resistance (~7.7k ohms) give it excellent load-driving capability and a relaxed, open sonic character. It is also commonly used as a phase inverter in push-pull power amplifiers where a 12AX7 would have excessive gain.

History

Introduced: 1946
Manufacturer: RCA·Amperex
Era: Golden Age

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