ABSTRACT
Microphones are called, as a general class, transducers, changing acoustical energy, sound, into electrical energy, voltage. They typically put out much lower voltage levels than most audio gear, so they must be amplified by a microphone preamplifier to be brought up to usable levels. A typical amount of voltage delivered by a professional microphone is 13 mV (0.013 V), a rather small voltage, for 94 dB SPL, 1 a rather loud level. Thus microphones must be connected to microphone inputs as opposed to line inputs, and the converse is true, too: line-level devices such as CD players must be connected to line-level inputs and not mic inputs. If a line-level device is connected to a microphone input, the result will typically be overload or bad distortion. If a microphone is connected to a line-level input, and the gain is raised high enough to hear the signal at all, the result will typically be quite noisy or hissy. The mic/line situation is complicated by the microphone attenuate (MIC ATT) switch on some cameras that allows high-level microphone outputs (when encountering loud sound) to be accommodated by low-level (more sensitive) microphone inputs.
