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As stated earlier, a receiver is the combination of a power amplifier, a preamplifier, and a tuner in a single enclosure. Although a receiver is more convenient in that it takes up less shelf space than separate units, unless it's a top-of-the-line unit, it is less flexible in terms of the number of units it can work with and it contains fewer features that directly affect sound quality.
To enhance the enjoyment of entertainment and facilitate the "home theater" experience, most of today's receivers, including some low-priced units, include some form of surround sound circuitry. The term "surround sound" is often used very loosely. Identical sounds coming from the front and rear of a listener can be described as surround sound. The same thing with slightly delayed rear sound reproduction also qualifies. Such surround sound can be used with music or any other sound sources but the forms of home surround sound reproduction that are specifically designed for specially processed movie soundtracks include Dolby Surround, Dolby Pro Logic Surround, Lucasfilm THX Home Theater, and Dolby Digital (formerly known as Dolby AC-3). But more on these systems later under Surround Sound.
Typical features for the tuner section of a receiver will include the tuning control(s), radio station presets, random access tuning controls, FM mute switch, high-blend switch, stereo/mono switch, Dolby FM switch, and multiplex filter switch.
A tuning control allows you to turn a knob or press a button or two to change radio stations.
Radio station presets electronically memorize your favorite radio stations. There are a variety of ways the memorization takes place. With many receivers, you first tune into to a radio station using the tuning control then press a "preset" or "memory" button for several seconds. This is repeatedly done for other radio stations. With other receivers, the radio station is tuned in using the tuning control. Instead of pressing a "preset" button afterwards, however, a separate button labeled "memory" is pressed then a the "preset" button is pressed. The number of radio stations a receiver can memorize depends, of course, on the number of preset buttons available.
By far, the fastest and easiest way to tune into your favorite radio station is through the use fo random access tuning controls. With this feature you simply enter the station number on a keypad on the front of the unit and your radio station is instantly reached.
FM mute switches are included only on older receivers that have mechanical knobs for manually tuning into radio stations. While tuning through radio stations using a mechanical knob, there are loud noises that are many times louder than the music coming from the radio stations themselves. With the FM mute switch turned on these noises are muted. This is both less annoying for the listener and it prevents damage to speakers.
The high-blend feature is useful for picking up weak FM radio stations. Since weak FM radio stations sound noisy high blend reduces the noise by reducing separation (see separation under tuner specifications) at high frequencies.
The stereo/mono switch also reduces noise on weak FM radio stations but does it by eliminating stereo separation (see separation under tuner specifications) altogether.
