The Schoeps CCM 4A LG Compact Cardoid Microphone for Close Pickup offers a strong low-frequency roll-off and 10 dB low sensitivity. This microphone is recommended for use exclusively in situations of very close pickup and high sound pressure levels. At greater distances, it would only deliver a low output level, resulting in an effective reduction in signal-to-noise ratio.
This compact microphone consists of 2 main components, an acoustic transducer (a capsule) and a microphone amplifier, which come together in the same body. The capsule is the component which converts sound waves into a varying electrical voltage. It determines the directionality and, for the most part, the sound quality of the microphone. The amplifier is the other main component, with the circuitry required to accept external powering, polarizes (charges) the capacitive capsule, obtains the audio signal from it, and converts that signal into one which is balanced and low-impedance. The circuitry of the microphone features a balanced, class-A output stage which does not use either coupling condensers or an output transformer. This leads to low output impedance, insensitivity to electrical interference, low distortion, and light weight.
This microphone has a bass roll-off filter with a low cut-off frequency of 20 Hz and a slope of 12 dB/oct. This frequency has been chosen to protect against perturbing, inaudible (infra-) sound that can be caused by ventilation systems, track vehicles, and wind. Although it is hardly noticeable, infrasound can cause strong audible distortions in the connected equipment when it leads to an overload. This would make it impossible to produce a recording that could be used. The audio range also only starts at around 20 Hz. Lower frequencies are only actually discernible at high levels which are only reproducible on few audio systems, and then quickly become unpleasant.
The CCM 4 A LG microphone is an electrically active component requiring operating current. It uses a standardized powering scheme known as phantom powering. Most recording equipment offers a 48V supply for such microphones. Some equipment, however, provides a 12V supply for phantom powering, or can readily be modified for such a supply. The CCM compact microphone can work with either voltage, switching its circuitry automatically to the corresponding mode of operation. It maintains the same level of performance in either mode while drawing only the necessary amount of current from the phantom supply.