phonostages

Phonostages, also called phono stages or phono preamplifiers, are electronic stages in hi-fi systems that prepare the signal from a turntable cartridge for further amplification. They provide the required gain and apply playback equalization, typically the RIAA curve, to restore the cartridge’s original frequency balance and reduce noise.

Most modern phonostages are active circuits (solid-state or tube), and they may be standalone units or built into integrated amplifiers. They accept different cartridge types, primarily moving magnet (MM) and moving coil (MC). MM cartridges are higher impedance and require moderate gain, while MC cartridges are lower in output and demand higher gain and lower input impedance.

A typical MM stage provides about 40–60 dB of gain with a fixed 47 kilohm input impedance; MC stages often provide 60–70 dB of gain and offer selectable low input impedances, commonly 100–1000 ohms depending on cartridge manufacturer.

Key design considerations include accurate RIAA equalization, input impedance matching, noise performance, and gain. Many phonostages offer user-adjustable loading for MC cartridges and gain trims to accommodate different systems.

Some designs include additional features such as rumble filters or subsonic filters, and step-up transformers for MC cartridges.

In use, the phonostage sits between the turntable and the line-level input of an amplifier or receiver. It is distinct from the line-stage preamplifier, which handles higher-level signals.