— How do I set capacitive and resistive loading for a Moving Magnet (MM) cartridge?
— There are a few "rules of thumb" that only apply to Moving Magnet and other high inductance cartriges (MI, fluxvalve, etc):
- The higher you go in resistive and capacitive loading, the "brighter" the sound is
- If the sound is too dull and lacks sparkle, increase resistive loading
- If the sound is too bright and tiring, decrease capacitive loading if possible. If not, decrease the resistive load
- No load adjustment is needed for modern MM-type cartridges (Ortofon OM/2M, Audio Technica VM, Sumiko and other Excel derivatives, Goldring). They are designed to be linear into a "standard" 47 kOhm/200 pF (picoFarad) load
- Typical tonearm cable has a 150-200 pF capacitance. Do not add more capacitive loading on the preamp side unless needed
Unlike the moving coil cartridges, there is no easy way to set the loading correctly. It will always be your subjective preference, unless you have a good test LP and a signal analyzer.
If you have the same recording on the LP and in digital format, and are happy with digital's tonal balance, you can try and match it by adjusting the loading. Digital releases are mastered differently, so there will never be an exact match.
Before the industry settled on today's typical 47 kOhm/200 pF loading, there existed considerable variation. In the 1970s, 75 kOhm loading was considered standard by some hi-fi manufacturers, and that's what the old Shures, Stantons and Pickerings might be expecting. If you have a vintage cartridge and it sounds dull, raise the resistive loading.
Many (but not all) 1970s, 80s and 90s Audio Technica cartridges are too bright into 47 kOhm. Loading them into 35 kOhm will result in a more linear response and a less fatiguing sound.