The CM 1A from Tube Tech is an opto based compressor module for use in the company's RM8 tabletop enclosure. The all tube based compressor is targeted at single-track recordings and is equally suited for delicate vocal recordings, as well as critical instrument recordings such as lead guitar, drums, bass etc.
The optical element is placed after the input-transformer and is followed by an all tube based amplifier with +30dB of gain. The compressor is controlled by the sidechain amplifier, which also contain the 2 time control circuits - one for fixed and one for variable attack/release. The 2 controllers can be used either separately or combined.
The amplifier consists of 2 tubes (valves) in push-pull configuration (one ECC 83 as the pre-amp and phase splitter, and one ECC 82 as the output stage), and an output transformer. Both the input and output are transformer balanced and fully floating, with a static-screen between the primary and secondary wirings.
A dedicated key switches the compressor in and out without clicks, although the amplifier remains in the signal path. An 11-segment LED display shows either output level (as VU-meter) or gain reduction. A red LED on top of the display, shows when output clipping is being approached. A dedicated bus selector with 3 positions is used whenever linking several compressors is required.