Fairchild 670 (Late 1950s)
A dual-channel vacuum tube compressor/limiter, designed in the late 1950s and one of the best-known audio processors in recording history.
Overview
The Fairchild 670 is a dual-channel tube limiter/compressor developed in the late 1950s by Fairchild Recording Equipment. It's known as "the grandaddy of all tube-based compressors." It has tube-driven amplification, selectable attack and release time constants, and custom-designed transformers. Less than 1,000 units were originally produced, which is why it's so rare. It became a staple in classic recordings.
Specifications
| Product type | 2-channel tube limiter/compressor |
| Frequency Response | 40Hz to 15kHz +/- 1dB |
| Input Impedance | 600 Ω |
| Output Impedance | 600 Ω |
| Input Level Range | 0 dBm to +16 dBm |
| Separation | 60 dB (A-B position) |
| Dimensions (W × H × D) | 482 × 359 × 229 mm |
| Weight | 90 pounds (40.8 kg) |
| Vacuum Tubes | 20 |
| Noise Level | 70dB below +4dBm |
Design
The Fairchild 670 is a Vari-Mu design with tube-driven amplification and custom transformers. The front panel has a control for push/pull cathode balance, which was a rare feature for its era. The unit houses 20 vacuum tubes, including four 6BC8 and four 6386 tubes per channel.
Context
Rein Narma developed the Fairchild 670 in the 1950s. It became the gold standard in studio compression and was used by well-known artists and engineers. It is often cited as the finest-sounding tube compressor in history, and it influenced many modern designs. The original 670 has been recreated in limited numbers, with reissues available at an MSRP of $35,000.
Market
Fewer than 1,000 original units were ever made, so the Fairchild 670 draws extreme collector interest. One unit was listed on eBay for $350,000.
eBay Listings
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