a. You know that audio frequencies range from about 15Hz to 20KHz. Television (TV)
equipments that amplify signals for sound reproduction use amplifiers designed for this low-frequency
range. It is the task of such amplifiers to strengthen the audio signal and reproduce it faithfully. The
dominant requirements are, therefore, gain and fidelity. The three types of audio amplifiers used in the
audio console are the preamplifier, driver, and power amplifier. The following is a list of their
functions.
b. Audio preamplifiers are designed to increase the gain of low-level signals from transducers
such as microphones and recorder-reproducer heads. They are operated Class A at power levels in the
order of micro-microwatts or microwatts. Since the signals are so very small, special attention must be
given to the noise factor, input impedance, and coupling.
Figure 1-1. Block diagram of a basic audio console
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