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Compressor/Limiter By Paul White
Published January 1995

Does ART's new model have anything new to offer in a market already well supplied with affordable compressors? Paul White finds out.

ART's CS2 joins an already large number of compressor/limiters in the marketplace, and on the face of it, offers little or nothing that is new. It features dual‑channel or stereo operation, hard or soft‑knee compression and on‑board gating to reduce noise, all familiar features, and if anything, it loses points because of the external wall‑wart power supply. This being the case, you might be surprised to find that I actually like this little unit.

Presented in a 1U rack case, the CS2 is remarkably conservative‑looking for an ART product, with all the controls clearly marked and no 'purple pizza' logos in sight. The rear‑panel in an out jacks are balanced, but accept unbalanced cables; unlike some budget compressors, the CS2 has a detector loop insert point, allowing equalisers to be inserted into the side‑chain for de‑essing and so on. This is wired like a console insert point, so you'll need either a stereo‑to‑two‑monos Y‑lead or a patchbay to make use of it.

The compressor interface is quite conventional, with Threshold, Slope, Attack, Release and Output Level controls for each channel, though why the term 'Slope' has been used in place of the more familiar 'Ratio', I don't know. A switch is used to select between soft‑knee and hard‑knee operation (soft‑knee being the more gentle of the two options), but a slightly unusual touch is a second switch for compressor/limiter selection. Most compressors require you to set the Ratio (Slope) control to maximum to perform limiting, and usually you need a fast attack time, but in the case of the CS2, one button push sets this for you, regardless of where the front‑panel controls are set, which is a nice little touch.

Another nice touch comes in the form of a couple of LEDs above the Threshold LED, one marked 'Below' and the other marked 'Above'. These simply indicate whether the input signal is reaching the threshold or not, but even though there is a separate gain reduction and input/output level meter, it seems to make setting up even more intuitive. The gain reduction meter is the usual LED ladder type, using 10 LEDs to cover the range 3dB to 30dB. The input/output meter has only six LEDs and covers the range ‑30dB to +5dB, with a push button to select between input monitoring and output monitoring.

Other than the mandatory compressor Bypass button, which hard‑wires the input directly to the output, all that remains is the gate. Though you wouldn't expect a full‑featured gate on a compressor/limiter, this one has the essential Threshold and Release time controls, and a gate LED which comes on when the signal is being gated. It isn't affected by the compressor Bypass switch, which means that you can use the gate on its own; if you need to turn the gate off, simply turn the Gate Threshold knob fully anti‑clockwise.

For stereo operation, there's a Stereo Link switch, which forces the right‑hand channel to follow the settings of channel 1. In this mode, the side‑chain signals are linked so that the same amount of gain reduction is applied to both sides, even when one channel is louder than the other. Without this, the stereo image would constantly tend to wander towards the quietest side.


Used on a variety of single tracks and complete mixes, the CS2 behaved very predictably — and that's one of the nicest compliments you can pay a compressor or gate. In soft‑knee mode, it behaves in a dutifully polite way, but switch it to hard and it takes command of the situation in a reassuringly confident manner. I particularly liked using the hard mode for bass guitar; it seemed to bring the level nicely under control, whilst still emphasising the punch and power of the bass.

The simple gate works well in keeping pauses clean, and because it has a good release time range, even slowly decaying sounds can be treated without being cut off in their prime. There are very few gripes; I've already mentioned my dislike of external PSUs for this type of equipment, and I would also have liked to see a few status LEDs on the switches, especially the Bypass, but there's nothing there I can't live with. On the whole, the CS2 is a really nice little compressor.


  • Maximum Input Level: +21dB
  • Dynamic Range: 117dB
  • Ratio: (Slope) 1:1 to limiting
  • Attack: 0.5mS to 50mS
  • Release: 50mS to 2S
  • Gate Release: 50mS to 2S
  • Output (Make‑up gain): ‑20dB to +20dB


  • Easy to set up.
  • Soft‑ and hard‑knee compression, and a gate, all in one unit.
  • Well‑written manual.


  • Wall‑wart PSU.


A very friendly, basic compressor that takes all routine jobs in its stride.