Warm Audio WA-2A Tube Optical CompressorThe WA 2A from Warm Audio recreates a classic optical tube compressor originally released in the late 1950's, a unit that is as desirable as ever, due to its ability to deliver smooth, "warm" compression for vocals and bass, among other instruments. True to the original design, the unit uses the classic four tube design, with dual transformers and the optical photo cell. The later item is responsible for the slow, gentle, and versatile multi stage