Tube-based Variable-Mu compressor

Originally designed for broadcast and cutting of lacquer masters for vinyl albums the Fairchild evolved into what is probably the most famous and coveted compressors of all time. Produced at the end of the 50´s there weren´t that many actually manufactured. Of those that remain, some 60 plus years later, only a small percentage have been properly maintained and are up to the job. This lush, punchy, warm sound has blessed 1,000s of hits and has never gone out of style. On the contrary, it´s desired as much today as it was when released, if not more…due to the digital age we live in. There´s an ever increasing need for that analog mojo to caress your mixes and Heritage Audio has the answer with the HERCHILD Model 670.


The HERCHILD Model 670 is a Tube-based Variable-Mu compressor that faithfully reproduces the design and exact components used in the original.Stuffed full of 22 valves and 9 transformers and operating at high voltage a solid, professional result is achieved. A clean, transparent sound is possible with no artefacts or pumping while also being able to create a more noticeable, heavier, denser effect with extra harmonics if pushed harder.

The original is a classic, but working in the 21st century we´ve come to expect certain features. The HERCHILD Model 670 will not disappoint. The 6 Attack and Release times have been exactly duplicated as has its all tube side chain circuit for precise control. There is now access to the progressive ratio, which is a unique curve adjustment combining control of the ratio and the knee. This is continually adjustable from hard limiting to a very smooth and transparent compression. There is also a side chain filter with 4 selectable frequencies to reduce the lower frequency´s influence on the signal, a must have nowadays.

The HERCHILD Model 670, being a 2 channel unit, also has the AGC section to determine which of the 4 modes it will work in. The 4 modes of operation to choose from are: IND, LINK, LAT VERT & LAT VERT LINK.IND gives you independent control for each channel while LINK, obviously, links the two channels operation together so both channels are controlled by taking the average from the two channel ́s settings to determine what the overall stereo control will be.

The LAT VERT mode is originally from the days of using a cutting lathe to prepare vinyl records. It was crucial to carefully decide the depth and the width of the grooves, so you had precise control over both aspects in this mode. Nowadays, people have discovered the advantages of mixing and mastering with MID/SIDE processing as it allows you creative control over the center and side signals of a stereo track separately. LAT VERT is the equivalent to MID/SIDE and when used properly it really gives you the control to make your songs sound wider, deeper and more focused. And the last option is LAT VERT LINK and is again for MID/SIDE processing but this time with the two channels linked together and controlled by taking the average from the two channel ́s settings to determine what the overall control will be.

  • Input Impedance: 2 kΩ.
  • Output Impedance: 600 Ω.
  • Output Level: +30 dBu clipping point.
  • Frequency Response: 20 Hz to 20 kHz ± 1 dB.
  • Signal To Noise Ratio: 120 dB.
  • Self Noise: Less than -82 dBu.
  • Harmonic Distortion: Less than 1 % at any level up to +18 dBu output (no limiting).
  • Watts: >200W.
  • Dimensions (W x H x L): 482 mm x 265 mm (6 Rack units) x 200 mm.
  • Weight: 13.3 Kg.
  • Input Impedance: 2K Ω
  • Output Impedance: 600 Ω
  • Output Level: +30dBu clipping point
  • Frequency Response: 40Hz to 15kHz +/- 1db
  • Self Noise: Less than -82dBu
  • Harmonic Distortion: Less than 1% at any level up to +18dBu output (no limiting)
  • Dimensions (W x H x L): 482mm x 265mm (6 Rack units) x 200mm
  • Weight: 13.3 Kg
Customer Ratings