CS 660P

About the CS 660P

The Leben CS 660P is a stereo power amplifier designed and manufactured by the Japanese company Leben Hi-Fi Stereo Company. It delivers 40 watts per channel in stereo mode and can be switched to monaural mode to provide 80 watts output. The amplifier uses four KT66 beam tetrode output tubes (with EL34/6CA7 tubes optional) working in a push-pull class AB ultra-linear configuration inspired by the classic Quad II design. The first amplification stage employs four 6CS7 General Electric double triodes (two per channel). A unique feature is the inclusion of a 6CJ3 dumper tube that delays the high-voltage B+ supply to the output tubes, protecting them from damage and extending their lifespan, while also influencing the sound character. The amplifier includes selectable output impedance (4, 6, 8, or 16 ohms) and can accommodate various output tubes with bias and heater current adjustments. It features high-quality components such as Japanese polypropylene capacitors, Nichicon Fine Gold capacitors, and Canare RCA inputs mounted in XLR fashion. The power supply uses a large transformer with multiple secondaries and a combination of solid-state diodes and the dumper tube for rectification. The CS 660P has a frequency response from 10 Hz to 180 kHz (-3 dB), total harmonic distortion of 0.7% at 10 watts, input sensitivity of 1.5 V at 40 watts, and input impedance of 100 kΩ. It weighs 17 kg and measures 415 mm (W) x 480 mm (H) x 320 mm (D). The amplifier is highly regarded for its sonic transparency, tube rolling flexibility, and robust build quality.