What is a phono cartridge?
The cartridge is the small component at the end of the tonearm. Its stylus follows the record groove and the generator inside converts that movement into an electrical signal. That signal is tiny: often a few millivolts from a moving-magnet cartridge and less than one millivolt from a low-output moving-coil cartridge.
The exact model matters. Two cartridges that both say “MC” can produce very different output levels and require different inputs.
What is a phono preamp?
A phono preamp — also called a phono stage — performs two essential jobs. It amplifies the cartridge’s small signal to a level that an amplifier’s AUX or LINE input can use, and it applies the RIAA playback equalisation that restores the record’s intended tonal balance.
RIAA itself should not be treated as a tone control. The useful adjustable settings are normally gain, resistance loading and, mainly for MM cartridges, capacitance.
The four compatibility checks
Type
Confirm whether the cartridge is MM, high-output MC or low-output MC. The label determines which input family to investigate.
Output and gain
A lower cartridge output needs more gain. Too little can sound quiet or noisy; excessive gain reduces overload margin and may distort.
Resistance loading
The cartridge sees an electrical resistance at the phono input. Use the cartridge maker’s recommendation as the starting point.
Capacitance
For MM cartridges, tonearm wiring, cable and phono input capacitance combine. Excess capacitance can alter the high-frequency balance.
MM, high-output MC and low-output MC
| Cartridge family | Typical output | Starting gain | Typical input |
|---|---|---|---|
| Moving magnet (MM) | 3–6 mV | 35–45 dB | 47 kΩ MM |
| High-output MC | 1.5–3.5 mV | 35–45 dB | Often 47 kΩ MM |
| Low-output MC | 0.2–0.8 mV | 55–65 dB | MC loading specified by maker |
These are screening ranges, not universal settings. The cartridge maker’s specification takes priority.
How phono gain is calculated
Gain in decibels can be converted into voltage multiplication. ELORUM’s Builder uses the cartridge output and phono gain to estimate the signal leaving the phono stage:
This is a useful compatibility screen, not a promise of final listening volume. The amplifier’s input sensitivity, recording level, phono-stage overload margin and volume control still matter.
WORKED EXAMPLE · LOW-OUTPUT MC
Sumiko Blue Point No. 3 Low with NAD PP 2e
The Sumiko produces 0.5 mV and specifies a load above 100 Ω. Its recommended tracking force is 2.0 g. NAD specifies 60 dB gain and a fixed 100 Ω MC input for the PP 2e.
Verdict: compatible — do not upgrade for compatibility. Gain is well matched. The fixed 100 Ω load is the limitation: it sits at the edge of Sumiko’s recommendation rather than above it. An adjustable MC phono stage could allow tonal fine-tuning, but that is an optional optimisation, not a necessary repair.
What does 100 Ω versus 200 Ω change?
Resistance loading influences how an MC cartridge interacts with the phono input. A lower value applies heavier electrical damping; a higher value applies less. The audible difference can include changes in openness, high-frequency energy and perceived control, but there is no rule that a higher number is automatically better.
Start with the manufacturer’s stated range. If the phono stage is adjustable, compare settings at matched listening volume and keep the one that sounds balanced across several familiar records.
Check these before upgrading
- Use only one phono stage. A turntable set to LINE should feed AUX/LINE, not another PHONO input.
- Select the correct input. A low-output MC normally needs MC gain; MM and most high-output MC cartridges normally use MM.
- Verify tracking force. Follow the cartridge maker’s range and measure it rather than guessing.
- Check grounding and cable routing. Hum does not automatically mean the phono stage needs replacing.
- Change one variable at a time. A repeatable improvement is more useful than a more expensive specification sheet.
Frequently asked questions
What does a phono preamp do?
A phono preamp raises the cartridge’s very small signal to line level and applies the RIAA playback equalisation required for records.
How much gain does a low-output MC cartridge need?
Many low-output moving-coil cartridges work within roughly 55 to 65 dB of gain, but the correct value depends on the cartridge’s output and the rest of the system.
Can an MC cartridge use an MM phono input?
A high-output MC can often use an MM input when the maker specifies 47 kilohms and sufficient output. A low-output MC normally requires an MC input or suitable step-up device.
Is higher MC loading always better?
No. Loading should follow the cartridge maker’s recommendation and can then be fine-tuned by listening when the phono stage allows it.
PRIMARY SOURCES