Amplifiers are available for retail sale in Smyrna. These are electronic equipment that work on the loudspeakers used in PA systems to make the human voice louder or play recorded music. Also known as amps, these are classified based on the input source, the target driving device, the frequency range of the signals, whether inversion of signal occurs or not, and the type of device used in the amplification. A number of different types and models are thus available. Amplifiers also come in combination with mixers.