Variable-mu limiters are unique in that they use tubes for gain reduction, and not just as amplifiers. The Fair- child 670 is a variable-mu tube limiter. Originating from the early 1950’s, the design of the 670 uses a single push- pull stage of amplification with an extremely high control voltage. With its 14 transformers, 20 vacuum tubes, 6 rack- space encompassing girth and weighing in at 65 pounds, the Fairchild 670 is truly the heavyweight champion of compression. The stereo Fairchild 670 is probably the “Holy Grail” of compressors in studio gear esoterica, not only because of its price (known to fetch $30,000 and be- yond on the vintage market), but also its extreme rareness and the difficulties in maintaining such a unit. The most famous Fairchild products produced were the 660 and 670 compressor/lim- iters, which are famous for their fantastic sound quality.
In the annals of compressor history, the products produced by Fairchild are some of the best built and most highly prized on the vintage market. UAD authorization download, and it's done.
