General Electric 5814a (ECC82, 12au7) 1953 - Clear

The 5814A is a premium, ruggedized military/industrial version of the standard 12AU7 medium-mu dual triode. It features heavy-duty plate structures and reinforced mica spacers designed to resist mechanical shock, vibration, and microphonics.

Direct Drop-In Substitutes

These tubes share the exact same pinout, plate voltage limits, heater current, and gain (\mu = 20):

12AU7 / 12AU7A – Standard commercial base type.

ECC82 – European commercial designation.

6189 / 6189W – Military-spec ruggedized equivalent (nearly identical build quality to the 5814A).

CV4003 / M8136 – British military high-reliability designation.

5814 / 5814WA – Base military variants and later upgraded revisions.

ECC802S / E82CC – Premium European special-quality audio variants with extended lifespan.

7730 – CBS/Hytron premium low-noise computer/instrumentation variant.

Conditional / Near Substitutes

These share the same 9-pin layout, but have slight operational differences to keep in mind:

5963 – Computer-grade dual triode with identical pinout and gain. It has a lower maximum plate voltage limit (250\text{V} vs. 300\text{V} for the 5814A), but works fine as a direct drop-in for most audio preamps running below 250V.

6211 – Medium-mu computer tube (\mu \approx 16). Shares pinout, but draws higher heater current (450\text{mA} at 6.3V vs. 300\text{mA}).

12BH7 – Taller bottle with higher plate dissipation (3.5\text{W}) and slightly lower gain (\mu \approx 16.5). It requires double the heater current (600\text{mA} at 6.3V), so only use it if your power transformer can supply the extra current.

Caution: While the 12AX7 (\mu = 100) and 12AT7 (\mu = 60) physically fit in the same 9-pin socket, their gain levels and bias requirements are vastly higher. They are not functional drop-in replacements for a 5814A/12AU7 circuit.