The Mode Machines FC-670, sold as the FairComp 670, is a rack-style compressor built as a clone of the Fairchild 670, the twin-channel tube limiter from the 1960s. Mode Machines describes it as "a very complex Fairchild 670 clone with 20 tubes and 8 transformers, completely made by hand in Germany", and as a 100% analog clone with no digital circuitry in the audio path1. It belongs to the same family of designs covered on the site's Compressor Pedals page, though at full rack dimensions rather than pedal size.
What it is based on
The Fairchild 670 was the stereo version of the Fairchild 660. Guitar Pedal X's Stefan Karlsson described the 670 as "The Dual Channel / Stereo 670 Model", noting that the original was "even more extreme with 20 of those RCA 6386 tubes, 11 hand-wound transformers" and 2 inductors23. Guitar World's Trevor Curwen described the 660 and 670 as "large, intricately engineered boxes"3. The FC-670 reproduces that design with 20 tubes and 8 transformers, and Mode Machines states that "The audio path circuit is 100% accurate to the historical model"1.
"The audio path circuit is 100% accurate to the historical model."
How it differs from the original
Mode Machines made some improvements over the historical design. The maker says the power supply is improved compared to the original, and that the signal-to-noise ratio was increased to 90 dB, "which is extremely good for a valve device"1. The Zero, Balance and DC-Threshold parameters, which sit inside the original unit, are moved to the outside of the FC-670, since players found those parameters useful for creative sound shaping1.
| Fairchild 670 (original) | Mode Machines FC-670 | |
|---|---|---|
| Tubes | 20 RCA 6386 tubes2 | 20 tubes1 |
| Transformers | 11 hand-wound2 | 81 |
| Inductors | 22 | not part of the maker's description |
| Signal-to-noise ratio | not given by the maker | 90 dB1 |
| Zero, Balance, DC-Threshold | inside the unit1 | on the outside panel1 |
| Build | historical instrument1 | hand-made in Germany1 |
The parameters Mode Machines brought to the outside panel are:
- Zero
- Balance
- DC-Threshold
Each of these sits inside the original Fairchild 670, and Mode Machines moved them because players found them useful for creative sound shaping1.
Mode Machines describes the FC-670 (FairComp 670) as a Fairchild 670 clone built with 20 tubes and 8 transformers, made entirely by hand in Germany with the same measurements as the original1.
Who it is for
Mode Machines positions the FairComp 670 as "an economical alternative for users who are looking for the legendary Fairchild sound in a modern device 'made in Germany', without the risks of a historical instrument, and at a fraction of the price"1. Each unit is made entirely by hand with the same measurements as the original Fairchild 6701. The maker's product page also carries a Magazine Reviews section for players who want published opinions before committing to a unit of this size and complexity1.
Videos
Gearspace Forum
Questions
Is the Mode Machines FC-670 analog or digital?
It is analog. Mode Machines describes the FairComp 670 as a 100% analogue clone of the Fairchild 670, with an audio path circuit the maker says is 100% accurate to the historical model. There is no digital processing in the signal path; the tubes and transformers do the compression the same way the 1960s original did.
What is the Mode Machines FC-670 based on?
It is based on the Fairchild 670, the twin-channel tube limiter and compressor from the 1960s. Mode Machines calls the FC-670 a very complex Fairchild 670 clone, built with 20 tubes and 8 transformers, and states that the audio path circuit is 100% accurate to the historical model.
How many tubes does the FC-670 use?
The FC-670 uses 20 tubes along with 8 transformers, according to Mode Machines. The maker's tube list includes 8 of the 6386 LGP JJ tubes, the type associated with the original Fairchild design. The original 670 itself was described by Guitar Pedal X as carrying 20 RCA 6386 tubes, 11 hand-wound transformers and 2 inductors.
Where is the Mode Machines FC-670 made?
The FC-670 is made in Germany. Mode Machines says each unit is completely made by hand in Germany, with the same measurements as the original Fairchild 670.
Is there a manual for the FC-670?
Yes. Mode Machines offers a PDF manual for the FairComp 670 as a download from the product's page on its website.
Sources (3)
- FC-670 | MODE MACHINES, Mode Machines, 2014-06-05
- Guitar Pedal X, Guitar Pedal X, 2024-03-21
- J Rockett Airchild 660 review, Guitar World, 2024-08-20
Roger McGuinn