What is Mic level?
Microphone level signals are generally transmitted as balanced signals, and their output impedance is usually below 300 ohms. This allows microphone level signals to be transmitted over longer distances compared to instrument level signals, which have high impedance outputs.
The output impedance of microphone level signals is typically low. This is because the signal generated by microphones is relatively weak in voltage. Such signals are considered low-impedance, meaning they have a relatively high current and low voltage. Low-impedance signals are generally suitable for long-distance transmission. The lower impedance helps maintain the strength of the signal and minimizes noise and signal loss.
link to instrument level document
However, transmitting microphone level signals over long distances like line level signals is challenging. This is because the distance over which the signal can be transmitted without affecting the audible frequency depends on the difference between the output and input impedance. The lower the output impedance and the higher the input impedance, the longer the distance over which the signal can be transmitted without affecting the audible frequency.
Although the output impedance of microphones is generally low, the input impedance of most microphone preamplifiers is not significantly high. As a result, unlike line level signals, microphone level signals are greatly influenced by the quality of the microphone cable and the impedance matching between the input and output devices. This emphasizes the importance of the quality of the microphone cable and impedance matching; if these are not well maintained, signal loss in the audible frequency range may occur.
Therefore, microphone level signals are transmitted as low-impedance signals and are usually fed into devices with lower output impedance and higher input impedance. However, if the input device doesn’t have sufficiently high input impedance, there may be signal loss in the audible frequency range, making it crucial to consider cable quality and impedance matching.
What is Microphone max Output level?
The max output level of a microphone indicates the highest level of electrical signal that the microphone can generate without distortion or clipping. This reveals the microphone’s capability to handle loud sounds without unwanted distortion.
Three key elements—Sensitivity, Max SPL, and Max output level—are closely interrelated, and understanding their correlation is crucial.
- Sensitivity: The sensitivity of a microphone is employed to convert input signal voltage to output signal. Usually represented in dBV or dBu, sensitivity indicates how efficiently a microphone can translate a low input signal to a high output signal.
- Max SPL (Maximum Sound Pressure Level): Expressed in dB SPL, Max SPL signifies the highest sound pressure level a microphone can handle. This depends on the internal structure and design of the microphone, representing its ability to manage high-pressure audio signals.
- Max Output Level: This represents the maximum size of the signal that the microphone can output and is generally expressed in dBV or dBu. It can be calculated using the microphone’s Sensitivity and Max SPL.
Higher Sensitivity means the microphone can turn even a weak input signal into a strong output signal. Similarly, a higher Max SPL indicates that the microphone can handle larger sound pressure levels, which in turn allows for a higher Max Output Level.
Thus, these three elements share a reciprocal relationship, collectively determining the performance and output capabilities of a microphone.
However, this does not necessarily mean absolute performance. The max output level can vary depending on the design and application. For example, dynamic microphones typically have higher Max SPL values than condenser microphones. The Neumann U87ai, often referred to as the “people’s microphone,” has a Max SPL of only 117 dB compared to Shure’s SM58, which has a 160 dB SPL.
Exceeding the max output level can result in distortion and clipping, which can degrade the quality of the recorded audio. Therefore, it’s essential to select a microphone with a max output level appropriate for the sound source and recording conditions.