12AU7 / ECC82 Cathode Follower Tube Preamp Schematic
This schematic below is a simple two stage line-level preamplifier using the 12AU7 / ECC82 tube. The overall gain of the circuit is about 8. The second stage of the circuit is a Cathode Follower and 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 for best results.
12AU7 / ECC82 Cathode Follower Tube Preamplifier Schematic