Focusrite Red 3

The Red 3 employs an unusual and original single-VCA design to achieve high quality and truly independent compression and limiting, without the compromise and unnecessary processing involved in traditional designs. The success of the design is attested to by the Red 3’s TEC award for Outstanding Technical Achievement in the Signal Processing Technology category.The VCA used is a proprietary Focusrite design, fully discrete and balanced, offering superb low noise and distortion, and excellent common-mode rejection.
The Red 3 has gone through 5 or more revisions since it was originally built. The early ones had rotary switches and banks of resistors instead of pots for some of the functions. And of course they also had the input transformers everyone desires. They also had an Unshielded Mains transformer, and different power supply for the VCA that caused more heat and went out more frequently that in the newer revisions.  These also lack the +14dB switch for the meters. Finally you could not "unlink" the compressor from the limiter like you can with the current units. In other words, on the new units you can use just a compressor or just a limiter or both.