Designed by American engineer/designer Rein Narma in 1959, the Fairchild 660 (one mono channel) and 670 (two channels, stereo linked) are widely regarded to be the first audio limiter/compressors that “sensed” the nature of the music at its input. Incorporating the ability to set multiple time constraints of both reduction and release from reduction, it was able to work at microsecond speed.
The 660 was designed to have a greater than 20dB headroom at input, while the 670's hand-wired design includes 20 vacuum tubes, 13 transformers and two inductors within its 65-pound (29kg) chassis. Narma built the first ten 660 units himself, on behalf of The Fairchild Recording Equipment Corporation. The first finished device shipped to pioneering jazz recording engineer Rudy Van Gelder; the third one went to Mary Ford, wife of Les Paul, for whom Narma would later build a recording studio.
Narma left Fairchild in the late 60s and the 670 was discontinued shortly after. The number of units made is thought to be around 1,000 but the exact amount is not known. Narma subsequently moved to the Ampex Service company, then to electronics developer General Instrument for twenty years, serving as executive vice-president and advisor to the chairman from 1984 to 1990. At the NAMM Foundation TEC Awards in 2007, Narma accepted an award for inventing the 660 and 670. He died in 2011.
The 670 is regarded as the "Holy Grail" of compressors due to its rarity value, (around $30,000 at the time of writing). Many music engineers use it for the subtle sonic enhancement as much as they do for gain-reduction. Geoff Emerick used it on all The Beatles vocals he recorded. “Just the sound of the amplifier, even if you didn't do any limiting, just added a certain presence,” he has said. Grammy award-winning engineer/producer Jack Joseph Puig, (U2, The Black Eyed Peas, Green Day) helped develop the 670 Universal Audio plug in. He talks of the 670's ability to make notes seem “long, lush and beautiful.”
In homage to the 670, London manufacturer Analoguetube Limited builds and manufactures classic tube technology of the 1950s and ’60s using traditional electronic methods. The AT-1 and AT-101 are designed to be natural sounding limiters that use the original circuits from the 660 and 670. Recent purchases and clients include Metropolis Studios in London, Abbey Road Mastering and producer/engineer Cenzo Townshend's Decoy Studios.
Pictures: (Top) Rein Narma in 2002 (c/o AES Oral History/YouTube) Bottom: The Fairchild 670.
Published earlier this year and sponsored by QSC Audio, Genius!2is the second edition of Genius!, celebrating those clever people whose inventions have transformed the world of professional audio. The 30-page supplement is also available to read in a handy digital-edition form