Fairchild 670 Tube Limiter

The Fairchild 670 was base don the Fairchild 660, a mono tube limiter also designed by Rein Narma, with around 800 units produced. The first ten units were hand built by Rein himself, and the first unit went to Rudy Van Gelder who used it to cut lacquers for Blue Note Records and Vox Classical records. The second unit went to Olmsted Sound Studios in New York where Jimi Hendrix would record some years later, but the third unit went to guitar legend Les Paul, himself an audio pioneer of epic proportions.

After establishing the Fairchild 660 among studio greats, Rein with the help of Fairchild, went on to develop the stereo Fairchild 670, which was released in 1959. The 670 used 20 tubes, 11 transformers and 2 inductors in a 6RU sized rack. The Fairchild 670 weighed a whopping 29.5 kg!

The Fairchild 670 (and 660 for that matter) is known for it’s fast attack time and slow release times. The fast attack time allowed the Fairchild 660 to be used in broadcast stations to prevent explosive peaks, but the Fairchild 670 being a stereo version allowed it to also be used for stereo lacquers in record production.

The Fairchild 670 has the ability to be used as a stereo compressor/limiter, or for lateral and vertical components of stereo disc cutting whereby the Fairchild 670 splits the two channels via a matrixing network, limits them separately and then combines them through a second matrix to preproduce the stereo signal once again.

The Fairchild 670 and 660 spent many years with great success in the broadcast space and disc cutting rooms. Eventually, studio engineers realised it’s value in the recording process and the Fairchild 670 and 660 took on a new life. Geoff Emerick was one of those engineers and while working at Abbey Road with The Beatles, started to use the Fairchild 660 on vocals, from Revolver onwards. The Fairchild legend simply grew from here, and today you will find Fairchild 670 and 660s still in use, if not certainly a clone of a Fairchild or even plugin version.

Compressor or Limiter?
The Fairchild 670 can be adjusted to work either as a compressor, with a ratio of 2 to 1 and a threshold of 5 db below normal program level; or as a peak limiter, with a compression ratio of 30 to 1 and a threshold of 10 db above normal program level; or it can be adjusted to operate anywhere in-between these two extremes.