Microphone Preamplifier With Active Filter

_,eptembe„x MICROPHONE PREAMPLIFIER WITH ACTIVE FILTER by S.G. Dimitriou When a microphone is used a good distance away from an amplifier, its relatively small output signal is inevitably affected by noise and attenuation caused by the cable. The simple, yet versatile, preamplifier/line driver described here can be used with a variety of microphones, has a user-defined frequency response, and prevents signal degradation because its ability to load long cables enables it to be installed near the signal source. Many types of modern audio equipment have a built-in microphone, or allow an external microphone to be attached semi-permanently. This is the general case with portable tape or cassette recorders, video and movie cameras. In spite of the apparent benefits of having a built-in microphone, this will almost always pick up mechanical noise from the equipment it belongs to. Also, it is of little or no use when sounds from remote sources are to be recorded, as the level of ambien...