LP66S Vacuum Tube Amplifier

by Conrad-Johnson
in Electronics

Consistent with conrad-johnson's design philosophy that circuits should be kept as simple as possible, the LP66S works its magic with just seven vacuum tubes. A composite triode input stage is direct coupled to a cathode-coupled phase inverter – the same improved wide-bandwidth driver stage found in our other, more costly LP amplifiers. The output stage is comprised of a pair of 6550s (each channel) operated in ultralinear configuration for an optimal combination of high power and low distortion. Limited negative feedback is applied to the circuit to reduce distortion and provide a sufficiently high damping factor to control most real-world speaker systems. Discrete dc power supply regulators are provided for the input and inverter stages, in order to isolate each stage from the output signal.