SE-300B

About the SE-300B

The Thöress SE-300B is a German-made monaural all-valve power amplifier built around one directly heated 300B triode per chassis. It uses single-ended, pure Class-A, zero-global-feedback circuitry and an in-house C-core output transformer. The 300B is driven by a one-stage circuit using a matched pair of EL822/CV2382 power pentodes wired as triodes and run at high idle current. Construction is hand-wired point-to-point in a non-magnetic aluminium chassis. One amplifier is required per channel. The product remains listed by Thöress, so it is treated as current production. Independent Stereophile lab measurements on an earlier sample found 6.85 dB voltage gain (8 ohms/1 kHz), approximately 90 kOhms input impedance at low/mid frequencies (62 kOhms at the top of the audio band), output impedance of 1.9 ohms at 20 Hz and 1 kHz rising to 2.4 ohms at 20 kHz, and 74 dB unweighted wideband S/N referenced to 1 W/8 ohms (79.2 dB audio-band; 95.7 dB A-weighted).