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The receiver is the heart of most of today's stereo systems. This component is actually the combination of three components: a preamplifier, a power amplifier, and a tuner. Although buying a receiver is generally more economical than buying the three separate components, performance may not always be as good and features may not be as specialized for the best performance. Economy and convenience will be the key advantages of most receivers; top-of-the-line receivers will emphasize a bit more on performance. Convenience will result mainly from the integration of the three separate components just mentioned.
A preamplifier supplies a minuscule amount of amplification (increase in sound level) to sounds fed to it from program sources. Program sources include the compact disc players, cassette, or reel-to-reel deck (tape machine), turntable, tuner (radio section), and any other unit that can provide a signal. The preamplifier can be recognized by its controls and switches. These controls and switches are provided to enable you to select a program source for listening or recording and to alter the character of the sound. In general, preamplifiers contain more of these switches than comparably priced receivers. Preamplifiers will also contain the most vital control, the volume control. Keep in mind, however, that a preamplifier by itself is not enough to amplify sounds from program sources to audible levels. All preamplifiers must be connected to power amplifiers.
The power amplifier contains few controls or switches. This component does exactly what its name implies: it amplifies signals. It takes the sound from the preamplifier and increases its level until it is loud enough to be audible. When consumers talk about "power" in terms of wattage they are referring to the level of sound the power amplifier is able to produce without unwanted artifacts. Artifacts include various forms of distortion, which can adversely affect the sound in a variety of ways. One inherent quality found in many power amplifiers is that they can drive a wider variety of speakers than receivers.
The tuner is what many consumers would call a "radio". This unit usually contains two radio bands: F.M. and A.M. This is one of the simplest components in a stereo system in terms of features. Tuning into a radio station is usually the only thing a listener needs to be concerned with. A tuner and a radio are, in fact, two different kinds of units. A radio is a tuner with a preamplifier, power amplifier, and speaker(s) built into it. In other words, it is a fully self-contained unit (usually a portable unit of inferior sound quality) and you can readily hear sound without the aid of a preamplifier, power amplifier, and speakers.
A slight variation of a receiver is an integrated amplifier. This component includes just the preamplifier and the power amplifier. As a result, a separate tuner must be connected to it if radio broadcasts are to be heard. In general, it is safe to say that an integrated amplifier sounds better than a comparably priced receiver. The best sound quality, however, can almost always be obtained using a separate preamplifier, power amplifier, and tuner. In other words, it is safe to assume that separate units almost always sound better than integrated units.
