12AU7 / ECC82 Cathode Follower Tube Preamp Schematic
12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic
This schematic below is a simple two stage line-level preamplifier using a single 12AU7 (ECC82) tube per channel. The overall voltage gain of the circuit is about 8. The output stage of the circuit is a Cathode Follower and is suitable to drive a low impedance amplifier. This circuit is from the RCA tube receiving manual.
The circuit is simple and does not require any unusual parts. For the power supply you can use a Hammond 370BX transformer with simple C-L-C or C-R-C filtering for the B+. You will want to use a good quality capacitor for C4 (audio grade polypropylene) for the best sonic results. We have had very good results using new production gold pin JJ ECC802S tubes.