Fairchild 670 — Fixed

Attack is fixed and program-dependent — faster on peaks, slower on sustained tones. This works beautifully for music but poorly for percussive sound design.

The original units are maintenance nightmares. They run hot, the tubes are expensive, and the capacitors can drift. Yet, the sound is so coveted that companies like Universal Audio have spent decades modeling the non-linearities of the transformers and the specific distortion characteristics of the tubes. fairchild 670

Modern digital compressors often offer attack times measured in microseconds (0.000001s). But the Fairchild’s fastest attack time is . That might seem "slow" compared to modern standards, but it is a sweet spot. Attack is fixed and program-dependent — faster on

The 6 positions are approximate RC time constants, but the actual release varies with program material. Position 3 might release in 150 ms on a snare hit but 300 ms on a bass note. They run hot, the tubes are expensive, and

The Fairchild, however, utilized a topology known as .

The Fairchild 670 was designed by Rein Narma in 1959. At the time, the recording industry was transitioning from cutting discs directly to using magnetic tape. They needed a limiter that could control the dynamic range of a performance without ruining the sonic fidelity.