The 800 Series Microphone Preamplifiers are designed for use in professional audio appplications. It has either one or two channels, designed to operate as a discrete microphone preamplifier. Dual channel cards will have two identical channels constructed on one printed circuit board. Typical applications are public address systems, broadcast studios, sales presentation rooms headphone listening systems, multi-room audio systems, and recording systems. The actual application of the amplifiers is found in buildings such as airports, factories, courthouses, casinos, convention centers, libraries, hotels, racetracks, training systems, corporate boardrooms, etc. The 800 Series Microphone Preamplifiers come in two different models. There is a single channel, model 808B, and dual channel, model 816B. Both models have low impedance transformer isolated inputs, and a push-on red jumper, per channel, to enable 15 volt phantom power. The gain of each channel is adjustable, from 17 to 56dB. The output section is balanced, transformer isolated.