What Is an Amplifier?
An electronic amplifier is a device that is used to increase the power, current, or voltage of a signal. Amplifiers are used in music equipment, electronic devices such as television and radio receivers, audio equipment, and computers to increase the amplitude of a signal.
How Does an Amplifier Work?
Amplifiers work by increasing a small input signal to deliver a larger output signal. Amps in audio equipment take tiny electrical signals that contain musical frequencies and amplitudes and increase their strength. When talking about power amps, this increases the power enough to drive speakers back and forth to generate air pressure variations, also called waves.
It does this by taking power from a power supply and increasing the output to match the (relatively low-power) input signal. This process invariably introduces some noise and distortion into the signal; and the process cannot be 100% efficient at increasing the gain without loss — amplifiers inherently will lose some energy in the form of heat. The ideal amplifier can be described as “a straight wire with gain,” as the output would be identical to the input, just greater.
Different Types of Amplifiers
Different amplifier designs are used for various types of applications and signals. We can broadly divide amplifiers into three categories — small-signal amplifiers, low-frequency power amplifiers, and RF (radio-frequency) power amplifiers. Each of these calls for a slightly different design approach, mainly because of the physical limitations of the components used to implement the amplifier and the efficiencies that can be realized. There are various types of amplifier classes, including Class A, Class B, Class AB, Class D, and more.
Preamp vs. Power Amp
Preamps and power amps may seem similar, but they have very different jobs. As its name suggests, a preamp comes before the power amp. A preamp is designed to strengthen an instrument’s weak output signal to line level by delivering high amounts of gain. When talking about guitar amps, preamps allow you to shape a power amp’s overall voice and character through features such as EQ controls (treble, middle, bass, and gain).
A power amplifier is used to boost the line-level signal so it can be projected through speakers at a higher volume. Power amp performance depends on the impedance, or resistance load, of the speakers. Learn more about power amplifiers by visiting our Power Amp Buying Guide.
