AnaMod® 660 Compressor

Recreating the classic Fairchild 660, AnaMod-style

  • Classic Variable-Mu compression
  • Authentic vintage tone
  • Six original 660 time constants plus two new variations
  • All analog—no latency or digital conversions
  • Single space 500 series module

The Fairchild 660 limiter is one of the most famous and sought-after compressors ever made. The magical way it adds density and dimension to a track or a mix has been demonstrated on many of the best-sounding records made in the last 50 years.

Using The AnaMod Process™ to model the complex transformer and tube interactions of the vintage hardware and re-implementing it entirely with analog components, the AnaMod 660 delivers a faithful recreation of the classic unit's sound and compression action. Unlike digital plug-ins or DSP-based outboard gear, there's no latency and no A/D or D/A conversions to compromise the sound.


“Most audiophile-sounding compressor in the group. You have to try hard to make it sound bad. Adds a smooth, buttery layer to drums, bass, and guitars.” —Electronic Musician

AnaMod 660 Specifications

  • Input Impedance: 20 kΩ, balanced
  • Output Impedance: less than 50 Ω
  • Input Gain: -15 to +15 dB
  • Max. Output Level: +27 dBu, balanced
  • Frequency Response: +/- 1 dB from 40 Hz to 15 kHz
  • Noise Level: better than 73dB below +4 dBu, 0-30 kHz
  • Limiting Noises: same level as a vintage 660 with GE five star 6386 tubes and properly balanced
  • Total Harmonic Distortion: level- and compression-dependent matching the original unit

Time Constants

Positions 1-6 are the original time constants. Positions 2a and 2b are variations on position 2 with longer release times suitable for vocal performances.

Attack Time
Release Time
0.2 ms
0.3 s
0.2 ms
0.8 s
0.2 ms
1 s
0.2 ms
2 s
0.4 ms
2 s
0.8 ms
5 s
0.4 ms
Auto, as in 660 #5
0.2 ms
Auto, as in 660 #6