Preamp · Dual triode
12AU7
Same type as ECC82
Low-gain dual triode used in hi-fi line stages, drivers and some guitar amp reverb and phase-inverter circuits.
Base: 9-pin miniature (noval)
- Specs checked against a cited datasheet
- No replacement verified yet
Where to buy 12AU7
- Apos AudioNo affiliate relationshipSearch 12AU7 on Apos AudioOpens apos.audio search results
Online audio retailer. Its catalog includes new and new-old-stock (NOS) vacuum tubes, such as 12AX7, 12AT7 and 12AU7 types.
- ReverbNo affiliate relationshipSearch 12AU7 on ReverbOpens reverb.com search results
Online marketplace for new and used music gear, including vacuum tubes.
Each button opens that retailer's own search for 12AU7. We don't see their prices or stock.
Before you buy, check that the listing names 12AU7 or ECC82. A listing that mentions another tube name isn't necessarily the same type. Affiliate disclosure
Other names
- ECC82 same type
European designation for the 12AU7 type.
Specifications
Checked against the manufacturer's datasheet. Source: General Electric 12AU7-A/12AU7/7AU7 data sheet ET-T880A, pp. 1–2 (dated 2-56) · checked Nov 5, 2026
From the datasheet: GE describes the 12AU7-A as a medium-mu twin triode for radio and television receivers and audio amplifiers, suitable as a general-purpose amplifier, phase inverter, oscillator or multivibrator.
Manufacturer's published ratings from the datasheet above, under the conditions shown. Another manufacturer's tube of the same type may be rated differently; check the datasheet for the tube you have.
| Heater | 12.6 V, 0.15 A (series) / 6.3 V, 0.3 A (parallel), 12AU7-A/12AU7 |
|---|---|
| Max plate voltage | 300 V DC (design-center, Class A1, each section) |
| Max plate dissipation | 2.75 W (design-center, Class A1, each section) |
| Max cathode current | 20 mA DC (design-center, Class A1, each section) |
| Max heater-cathode voltage | 200 V total DC and peak, heater positive or negative; 100 V DC component with heater positive (design-center) |
| Operating point | Class A1, each section: 250 V plate, −8.5 V grid |
| Amplification factor | 17 |
| Plate resistance | 7,700 Ω (approx.) |
| Transconductance | 2,200 µmhos |
| Plate current | 10.5 mA |
What these figures mean
- Heater (series / parallel):
- the voltage and current the heater needs. A center-tapped heater can run from a 12.6 V supply (halves in series) or a 6.3 V supply (halves in parallel) (GE 12AX7 data sheet ET-T509B, p. 1).
- Max ratings, design-center:
- limits for a typical tube of the type that equipment should not exceed under normal conditions (GE 12AY7 data sheet, p. 1).
- Max ratings, absolute:
- limits that supply variation, component tolerances and control settings combined must not push past (GE 12AU7-A data sheet ET-T880A, p. 2).
- Operating point:
- the plate and grid voltages at which the figures below it were measured. They describe the tube there, not in any particular amplifier.
- Amplification factor (µ):
- how much the plate voltage varies in relation to the grid (input) voltage (US Navy NEETS Module 6).
- Transconductance:
- how much the plate current varies with the grid (input) voltage (US Navy NEETS Module 6). 1,000 µmhos is 1 mA per volt.
- Plate resistance:
- plate-voltage change divided by plate-current change at a fixed grid voltage; it equals µ divided by transconductance (Lessons in Electric Circuits, “Tube Parameters”).
- Plate current:
- the current each section draws at the operating point shown.
These figures alone don't show whether one tube can replace another; heater, pin connections and ratings must suit your amplifier.
Common uses
- hi-fi line stage
- driver
- phase inverter