Discrete Head Amp by John Linsley Hood

A head amp (short for head amplifier) is a very low-noise preamplifier designed to boost the tiny signal from a moving-coil (MC) phono cartridge up to the level of a moving-magnet (MM) cartridge, so that a regular MM phono preamp can handle it. Gain: 33.6dB with switch closed / 20dB with switch closed. Here’s how it fits in the signal chain: Turntable (MC cartridge, ~0.2 mV) → Head amp (gain 20–30 dB, flat, no EQ) → MM phono preamp (with RIAA EQ and ~40 dB gain) → Line level (~1 V) → Amplifier Key features of a head amp: • Very low noise: Because MC cartridges put out microvolt-level signals, the head amp has to add gain without introducing hiss. • Flat frequency response: Unlike the phono stage, the head amp does not apply RIAA equalization — it just amplifies cleanly.

published 8 months ago