McIntosh 12AT7, dual triode tube

The 12AT7 is a small-signal dual triode from the ECC81 type family. It contains two separate triode systems in a common glass envelope and is used in appropriately designed amplifier circuits for signal amplification and driving subsequent stages.

Compared to the 12AX7A, it has a lower typical gain factor, but at the same time a higher transconductance and a lower internal resistance at the usual operating points. These properties make it suitable for certain driver and buffer applications. Transconductance describes how strongly the anode current changes with a change in the control grid voltage.

McIntosh uses the 12AT7, for example, in the MC1502 for voltage and driver amplifiers. In the MC3500 Mk II, it takes over the buffer and driver function for the power tubes. Its role is thus determined by the specific circuit.

Although the 12AT7 and 12AX7A use the same socket type, their electrical characteristics differ. Interchanging these types changes the operating conditions and is only permitted if it is expressly intended for the device in question.

Tube type: 12AT7.
Type family: ECC81.
Design: Dual triode with two triode systems.
Socket: Nine-pin Noval socket.
Typical gain factor µ: Approximately 60.
Typical heater data: 6.3 V at 300 mA or 12.6 V at 150 mA.
Function: Model-dependent voltage amplification, buffering, and driver function.
Replacement selection: According to the equipment manual regarding population and tube position.

Warranty: The warranty terms in our General Terms and Conditions apply.