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| Fairchild 670 | |
|---|---|
| Name | Fairchild 670 |
| Manufacturer | Fairchild Corporation |
| Introduced | 1954 |
| Type | Vacuum tube limiter/leveling amplifier |
| Applications | recording studio, broadcasting, motion picture |
Fairchild 670 The Fairchild 670 is a landmark vacuum tube stereo limiter/leveling amplifier introduced in the 1950s. It played a central role in recording studio dynamics control, influencing practices at facilities like Capitol Studios, Abbey Road Studios, and Motown. Its complex tube circuitry and proprietary control topology made it prized by engineers associated with RCA Victor, Columbia Records, and independent producers such as Phil Spector and George Martin.
Fairchild 670 development began under the direction of Leslie "Ted" Fairchild engineers collaborating with designers linked to Bell Laboratories and alumni of RCA. The design synthesized concepts from pioneers at Western Electric, AT&T, and contemporaneous efforts at EMI and Telefunken. The unit employed a stereo-linked topology to provide matched dynamics processing for two channels used in sessions with artists represented by labels like Capitol Records and Decca Records. Its ergonomics and front-panel layout reflected input from studio managers at Sun Studio and executives at United Artists.
The Fairchild 670 used multiple vacuum tubes including types produced by General Electric and Philips (company), high-voltage transformers similar to those from Hammond Organ Company, and discrete resistive networks resembling parts used by Amphenol and Vishay. The amplifier provided variable time constants, selectable via controls inspired by research at Bell Labs and designs from Telefunken engineers. Its circuitry incorporated matched resistors and capacitors comparable to components used in Neumann microphone preamplifiers and referenced in schematics circulated among engineers at Universal Audio and dbx (company). The unit's gain reduction meter and switching reflected measurement practices from IEEE standards and test procedures used at National Bureau of Standards.
Studios and engineers used the Fairchild 670 to control dynamic range on recordings for artists signed to Atlantic Records, Columbia Records, Sun Records, and Stax Records. Its characteristic program-dependent attack and release informed the sonic character of records produced by Quincy Jones, Brian Wilson, and Phil Spector. Broadcast facilities for NBC and CBS (Columbia Broadcasting System) deployed the 670 for program leveling and live transmission. Motion picture audio post-production facilities at Metro-Goldwyn-Mayer and 20th Century Studios used matched pairs for stereo film mixes and archival transfers.
The Fairchild 670 appears in the equipment lists of engineers who worked with The Beatles, Frank Sinatra, Sam Phillips, Berry Gordy, and George Martin. Iconic albums attributed to sessions at Abbey Road Studios, Capitol Studios, and Gold Star Studios list the 670 among tools used by producers like Phil Spector, Brian Wilson, Tom Dowd, and Glyn Johns. Broadcast engineers at NBC and BBC credited the device in program logs alongside gear from Telefunken and RCA. Classical and orchestral recordings released on Decca Records and EMI also cite the 670 in session documentation compiled by producers such as John Culshaw.
Manufacture of the Fairchild 670 was undertaken by Fairchild Corporation facilities with subcontracted components from suppliers such as Hammond, Western Electric, and Bell Labs era vendors. Production runs were limited; units were assembled and calibrated by technicians trained in procedures similar to those used at Bendix Corporation and H.P. test labs. Military and industrial procurement practices of the 1950s influenced component sourcing from firms like RCA and Philips (company). Surviving examples became collectors' items traded among dealers in Los Angeles, Nashville, and London.
The Fairchild 670 influenced later designs at Universal Audio, UREI, dbx (company), and boutique manufacturers inspired by vintage gear such as Neve Electronics and API (Automated Processes, Inc.). Its program-dependent compression characteristics are studied in curricula at institutions like Berklee College of Music, Institute of Contemporary Music Performance, and referenced in publications from Audio Engineering Society. Modern digital emulations and hardware clones by companies in London, Los Angeles, and Nashville cite the 670 as a benchmark alongside processors from SSL (Solid State Logic) and Neve Electronics. The unit's status in collecting communities places it in the same rarified category as rare microphones from Neumann, preamplifiers by Custom Electronics makers, and classic consoles used at Sun Studio.
Category:Audio equipment