The main differences between moving coil and moving magnet systems lie in their construction, operation, and applications, particularly in the context of audio equipment such as phono cartridges and loudspeakers. Here are the key distinctions:
Moving Coil (MC) Systems
Construction:
- Coil Movement: In a moving coil system, the coil is attached to the diaphragm or cantilever and moves within the magnetic field. The magnet is fixed.
- Coil Size: The coil is usually smaller and lighter since it needs to move to generate a signal.
Operation:
- Signal Generation: When the coil moves within the magnetic field, it cuts through the magnetic lines of force, inducing a voltage (Faraday's Law of Electromagnetic Induction).
- Impedance: Typically has lower output impedance and generates a smaller voltage signal, requiring additional amplification.
Applications:
- Phono Cartridges: MC cartridges are often preferred by audiophiles for their high fidelity and precision in sound reproduction.
- Loudspeakers: Commonly used in high-end loudspeakers and microphones due to their accurate response and sensitivity.
Advantages:
- Sound Quality: Generally provides better sound quality with more detailed and accurate reproduction.
- Durability: Fewer moving parts lead to potentially longer-lasting performance.
Disadvantages:
- Cost: Typically more expensive due to the precision required in their construction.
- Complexity: Requires specialized pre-amplification due to lower output signals.
Moving Magnet (MM) Systems
Construction:
- Magnet Movement: In a moving magnet system, the magnet is attached to the diaphragm or cantilever and moves, while the coil remains fixed.
- Magnet Size: The moving magnet is usually larger and heavier compared to the moving coil.
Operation:
- Signal Generation: As the magnet moves within the fixed coils, it induces a voltage in the coils.
- Impedance: Typically has higher output impedance and generates a stronger voltage signal, which can directly interface with standard amplification systems.
Applications:
- Phono Cartridges: MM cartridges are commonly used in turntables due to their ease of use and compatibility with standard phono inputs.
- Loudspeakers: Less common in high-end applications, but still used in some entry-level and mid-range equipment.
Advantages:
- Cost: Generally less expensive and easier to manufacture.
- Ease of Use: Higher output signals mean they can be used with standard amplification without additional pre-amplification.
Disadvantages:
- Sound Quality: While still capable of high-quality sound, they are generally considered to be less precise than moving coil systems.
- Weight: The heavier magnet can limit the system's responsiveness and accuracy.
Summary
- Moving Coil (MC): High fidelity, lightweight coil, lower signal output, more expensive, and preferred by audiophiles.
- Moving Magnet (MM): More accessible, heavier magnet, higher signal output, less expensive, and easier to use with standard equipment.
These differences make each type suitable for different applications and user preferences, with moving coil systems being favored for their precision and sound quality, while moving magnet systems are valued for their practicality and affordability.