What is Mic level?
What is Mic level?
Some mixers and active speaker have switches on the rear panel for setting each input jack or output jack for mic level (XLR) or line level (1/4″). These terms refer to the signal level or intensity.
Microphone level is in the region of -60 dBV (0.001 volt) to -40 dBV (0.010 volt). (dBu and dBV are decibel measurements relative to voltage). The professional microphones output what is known as a Mic Level signal.Including moving-coil microphone and Condenser Microphone. This is a low impedance signal ranging typically from 200 ohm to 1000 ohm, nominal impedance 600 ohm, carried on a microphone cable with 3-pin XLR cable connectors.
Mic level or microphone level signal is the voltage level that comes out of a microphone when someone speaks into it, typically just a few ten-thousandths of a volt. Of course, this voltage varies in response to changes in voice level and and in the talker-to-mic distance. But the signal is still quite small.
Because of the interference rejection provided by balanced mic signals, microphone cables can be run in long lengths. Multicore cables, often with stage boxes attached at one end, are really just many length of balanced microphone cable bound together and can be as long as 70m. Running a mic signal a long length will result in a small amount of signal loss, but it generally not an issue due to the fact that all mic signals are later boosted by a preamp.
Once the mic signal arrives at the mixing desk or active speaker, it is hopefully free of interference noise, but will require the preamp to boost the mic level signal up to an appropriate level for the mixing desk and other audio processing equipment to use. At this stage, the mic level signal has been changed to a ‘Line Level’ signal.
Microphones, similar to speakers, perform best when the impedance’s are matched. That is saying that the output impedance (600 ohm) of the microphone should match, or be as close as possible to the rated impedance of the preamp input. Some preamp’s have a control to adjust the impedance of the input, to better suit different microphones.
Some modern condenser mics have quite a high output. When using them with a loud sound source such as drums or vocals with phantom power (+48v) enabled, they can be plugged directly into a compressor or mixing desk without the need for a pre-amp.
A mixer will not only boost a microphone level signal, but it will also combine multiple signals together into a single output. There are also devices called Mic preamplifiers or Mic-to-Line amplifiers. These are available as single-channel or multi-channel devices.
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