The sensitivity of a moving coil microphone typically falls within the range of 1 to 4 mV/Pa (millivolts per Pascal). Some higher-performing moving coil dynamic microphones can achieve sensitivities of 3 to 4 mV/Pa. When expressed in decibels, this corresponds to approximately –60 to –48 dB re 1V/Pa (decibels relative to 1 Volt per Pascal).
Understanding Microphone Sensitivity
Microphone sensitivity is a crucial specification that indicates how efficiently a microphone converts sound pressure into an electrical signal. Essentially, it tells you how "loud" the microphone's output signal will be for a given sound input. A higher sensitivity value (e.g., more mV/Pa or a less negative dB value) means the microphone produces a stronger electrical signal for the same sound level, requiring less amplification from a preamplifier.
Sensitivity of Moving Coil Microphones
Moving coil microphones, a common type of dynamic microphone, generate an electrical signal by moving a coil of wire within a magnetic field. Their design inherently offers robust construction and good sound quality for various applications, though their sensitivity is generally lower compared to condenser microphones.
- mV/Pa (Millivolts per Pascal): This unit expresses sensitivity as the output voltage (in millivolts) generated when the microphone is subjected to a sound pressure level of 1 Pascal (Pa), which is equivalent to 94 dB SPL (Sound Pressure Level).
- dB re 1V/Pa (Decibels relative to 1 Volt per Pascal): This is a logarithmic scale where sensitivity is measured in decibels relative to a reference output of 1 Volt per Pascal. A less negative dB value indicates higher sensitivity.
How Moving Coil Sensitivity Compares to Other Microphones
The sensitivity of moving coil microphones positions them well for many live sound and studio applications, particularly for loud sound sources.
Here's a brief comparison of typical microphone sensitivities:
| Microphone Type | Typical Sensitivity (mV/Pa) | Typical Sensitivity (dB re 1V/Pa) | Key Characteristics |
|---|---|---|---|
| Moving Coil | 1 to 4 (some 3-4) | -60 to -48 | Robust, durable, good for high SPLs, requires more gain than condensers. |
| Ribbon | Lower end of dynamic range | -60 to -48 (lower end) | Fragile, warm vintage sound, very low output often requiring specialized preamps. |
| Condenser | Much higher | Much higher (e.g., -42 to -30) | High output, detailed sound, requires phantom power, ideal for studio recording. |
Practical Implications
The sensitivity of a moving coil microphone means that for typical speech or singing, it will produce a relatively lower output signal compared to a condenser microphone. This often necessitates the use of a preamplifier to boost the signal to a usable level for mixers, audio interfaces, or recorders. High sensitivity microphones are generally preferred for capturing subtle sounds or working in quiet environments, while lower sensitivity microphones (like many moving coils) are excellent for high sound pressure level (SPL) sources such as vocals, drums, and electric guitar cabinets, as they are less prone to overloading.
