Drawing from one of the most famous limiters ever, the old-school Fairchild limiter, the Manley Labs Variable MU is a stereo tube compressor/limiter that uses a remote-cutoff tube rather than a VCA or optical cell to carry out the actual gain reduction. Though older models made between 2000 and 2009 did not have the sidechain highpass filters standard in modern units, there were custom-ordered MUs that contained these filters. The original units used the same tubes as the Fairchild 660/670, the 6386 tubes, but most units nose use the 5670 for gain reduction (though these can be modded to replace those tubes with 6BA6 tubes to more closely match the Fairchild's composition). The Variable MU can be found in recording studios worldwide for its amazing vocal processing.