Phono Preamplifier

A phono preamplifier raises the extremely faint signal of a turntable cartridge to line level while correcting the standardised RIAA equalisation. Without this component, vinyl sounds quiet, bass-light and treble-heavy. Depending on the cartridge type – moving magnet (MM) or moving coil (MC) – the requirements for gain and input impedance differ considerably.

How does a phono preamplifier work?

Records are cut with a standardised frequency response curve: bass is reduced during recording and treble is boosted – this is the RIAA curve. The phono preamplifier reverses this process precisely, producing a neutral sonic character. At the same time it amplifies the weak cartridge signal by a factor of 100 to 1000, depending on the system type.

MM cartridges typically deliver 2–6 mV output voltage and require an input impedance of 47 kΩ. MC systems often generate only 0.2–0.5 mV and therefore require significantly higher gain as well as lower input impedances between 10 and a few hundred ohms. High-quality phono stages offer switchable or adjustable values to match different cartridges optimally. A correctly matched phono preamplifier affects not only the volume but also the dynamics, the noise behaviour and the spatial imaging of the playback considerably. The quality of the components used – capacitors, resistors and amplifier circuits – decisively determines how precisely the RIAA equalisation is carried out and how low the inherent noise remains.

What to look for when buying used?

Older phono preamplifiers can develop hum or distorted bass due to aged electrolytic capacitors. Pay attention to interference-free playback in quiet passages – noise or crackling that does not come from the record indicates worn components. Oxidising switches for MM/MC switching sometimes cause crackles when switching.

Check whether the unit matches your cartridge: a pure MM preamplifier provides too little gain for MC systems. Conversely, an MC input can overload with MM systems. At Audio Everywhere (a hi-fi specialist shop in Goslar-Hahnenklee, Germany) you can test tested units on site with your own system.

Typical variants at a glance

Frequently asked questions

Do I need a separate phono preamplifier?

If your integrated amplifier or receiver has no phono input, an external phono preamplifier is mandatory. Even with an existing phono input, a high-quality external stage can bring sonic advantages, especially with demanding cartridges.

What distinguishes MM from MC phono stages?

MC stages amplify more strongly and work with lower input impedances because MC cartridges deliver less voltage. MM stages are designed for the higher output voltages of moving-magnet systems and require the standardised 47 kΩ input impedance.

How do I recognise a defective phono preamplifier?

Persistent hum regardless of the connected turntable, distorted bass, strong noise at low volume or channel imbalances are typical signs of ageing. A brief listening test with familiar music material quickly provides clarity.

Can I connect any phono preamplifier to any amplifier?

Yes, the output of a phono stage delivers line level and fits any high-level input such as AUX, CD or Tape. Do not connect it to another phono input, as this would result in double equalisation and amplification.

Browse our range of used hi-fi equipment or learn about more technical terms in the hi-fi glossary. Detailed equipment descriptions can be found in the equipment archive. We publish current news about vinyl and hi-fi in the Audio Everywhere Journal.