The EL8X Distressor from Empirical Labs is an automatic gain (or volume) control device (AGC in engineering terms) designed for pro audio applications. Basically, the compressor electronically controls the volume of just about any source in a very pleasing, and "musical" manner—adding fullness, intelligibility, and especially in the Distressor's case—excitement. This type of device is often called a "limiter" or "compressor" by audio professionals and its most probable uses will be in recording studios, live sound situations, movie sound production, and radio broadcast production.
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