Blochead Diamond Buffer

The circuit is designed to run off a 100k volume pot, and be either a line stage or a headphone amplifier. It is a standard non-inverting gain stage (A=15dB) followed by discrete copy of the old LH0002 buffer IC. The basic idea is that the four transistors in the buffer will be carefully matched to ensure low output offset voltages and low distortion, so that it will not be necessary to include it in the op amp feedback loop.

The rather primitive buffer is inefficient as the driver transistors must pull as much current as the output devices, so the total current is about 3x more. It also means the damping resistors on the output emitters can only be very tiny otherwise the output stage pulls no static current and reverts to class B operation. I am drawn to the minimalist design however.

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