The STM-1 is a low-cost quality microphone preamplifier designed for use in commercial sound and broadcast applications. The compact size makes it ideal where a larger or heavier preamp cannot be used. The high-performance circuit provides a fixed 50 dB gain to bring any mic level signal up to the line level range of nearly any line input. The STM-1 supply input is single ended and operates from 24 to 33 Vdc. Operation from 12 Vdc is possible with a 6 dB reduction in headroom. For intercom applications, the input will operate directly from a speaker.