No component in a hi-fi system has more interdependencies than the phono cartridge. It must be matched to the tonearm for correct resonance frequency, to the phono preamplifier for appropriate gain and loading, and to the stylus for correct alignment geometry. Get any of these wrong and the performance penalty is immediate and audible.
MM vs MC: The Fundamental Choice
The two dominant cartridge technologies — Moving Magnet (MM) and Moving Coil (MC) — produce sound through opposite mechanical arrangements, and each demands a completely different phono preamplifier.
Moving Magnet (MM)
- Output voltage: 3–6 mV
- Internal impedance: 500–2,000 Ω
- Load impedance: 47 kΩ (standard)
- Phono gain needed: 35–45 dB
- Compliance: Typically medium-high (15–25 µm/mN)
- Stylus: User-replaceable
- Best with: Low-to-medium mass tonearms
Moving Coil (MC)
- Output voltage: 0.2–2.5 mV
- Internal impedance: 3–200 Ω
- Load impedance: 50–1,000 Ω (adjustable)
- Phono gain needed: 55–70 dB
- Compliance: Typically low-medium (5–15 µm/mN)
- Stylus: Requires factory retipping
- Best with: Medium-to-high mass tonearms
Output Voltage and Phono Stage Gain
Output Voltage (mV at a stated velocity)
Cartridge output is specified in millivolts at a reference groove velocity — typically 1 kHz at 5 cm/sec lateral velocity. This figure must match the gain and input sensitivity of your phono preamplifier. A low-output MC producing 0.35 mV cannot be used with a standard MM phono stage (which provides only 40 dB of gain) — it would need the 60+ dB of an MC stage. Conversely, a high-output MM at 5 mV fed into a high-gain MC stage will overdrive it.
Dynamic Compliance and Tonearm Resonance
Dynamic Compliance (10−⁶ cm/dyne or µm/mN at 100 Hz)
Dynamic compliance describes how freely the cartridge cantilever moves laterally. Combined with the tonearm's effective mass, it determines the tonearm-cartridge system resonance frequency. This resonance must land between 8 Hz and 12 Hz. Below 8 Hz it becomes susceptible to record warps. Above 12 Hz it encroaches on the audible range, adding a bass coloration and potential mistracking.
The resonance frequency formula is:
Tonearm–Cartridge Resonance Frequency
F = 1000 ÷ (2π × √(M × C))
Where F = resonance frequency (Hz), M = effective tonearm mass (grams), C = dynamic compliance (µm/mN)
For example: a cartridge with 12 µm/mN compliance paired with a tonearm of effective mass 10 g gives a resonance of approximately 10.3 Hz — ideal. The same cartridge in a heavy 20 g tonearm drops to 7.3 Hz — too low, creating warp susceptibility. In a light 5 g tonearm the resonance rises to 14.5 Hz — too high, audible coloration.
Practical rule: High-compliance cartridges (18+ µm/mN) need light tonearms (8–12 g effective mass). Low-compliance cartridges (below 10 µm/mN) need heavier tonearms (14–24 g). The AudioChainHiFi analyzer calculates this resonance frequency automatically.
Cartridge Loading
MM Loading: Capacitance Matters
MM cartridges are loaded at 47 kΩ input impedance — the universal standard. But MM cartridges also interact with the total capacitance of the phono cable plus the phono stage's input capacitance. The cartridge's internal inductance and this capacitance form a resonant circuit at the top of the audio range. Most MM cartridges are designed for 100–200 pF of total load capacitance. Too little capacitance and the high-frequency resonance rises, adding brightness. Too much and it shifts down into the treble, causing rolloff. Check the cartridge manufacturer's capacitance recommendation and measure (or estimate) the capacitance of your phono cable.
MC Loading: Resistance is the Variable
MC cartridges are loaded by the input impedance of the phono stage — typically a switch-selectable value from 50 Ω to 1,000 Ω or higher. The general rule is that the load impedance should be at least ten times the cartridge's internal impedance. A cartridge with 10 Ω internal impedance works well loaded at 100 Ω or above. Lower loading damps the cartridge and rolls off high frequencies; higher loading allows a natural resonance that some listeners find bright. The "correct" MC loading value often requires listening experimentation within the recommended range.
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