MM load capacitance
The capacitance a phono input presents to a moving-magnet (MM) cartridge, measured in picofarads (pF).
This input value excludes the turntable’s tonearm wiring and cable. Add their capacitance to find the total load the cartridge sees. Check the documented values rather than assuming the cable contributes nothing.
In a phono preamp
Capacitance loading can change the cartridge’s tonal balance, particularly its treble. The highest setting is not automatically best: match the combined total to the cartridge maker’s recommendation.
For example, suppose the input is 100 pF and all the tonearm wiring and cable together add 100 pF. The total is 200 pF, within a cartridge’s stated 100–200 pF recommendation. Comparing only the input would miss half the load.
Some phono inputs have fixed capacitance; others offer selectable settings. Check the preamp’s specification or manual to see which applies.
Sources
- C 165BEE manual, p. 7: MM loading — NAD Electronics
- VM760SLC manual: recommended load capacitance — Audio-Technica
- Phono Box E: input specifications — Pro-Ject Audio Systems
Sources
- Nº32 Phono manual, p. 24: capacitive loading — Mark Levinson