Compression ratios on the C-128 are adjustable from 2:1 for an easy squeeze of the sound or all the way up to 50:1 for very hard limiting. The attack time (or time it takes for this action to happen) is adjustable from 0.05 milliseconds to 50 milliseconds. Likewise the release time (or the time the compressor releases from gain reduction and returns to normal) is selectable from 50 MS to 1.l seconds.

The input control establishes the input level threshold point the unit starts to compress and an output control provides up to twelve db of gain makeup. There is a handy overload indicator that informs the user that one or more points in the unit's circuitry are at the clip point. There is also a ten-segment gain reduction LED meter indicator.

A useful feature for the C-128 in its price range is the De-Ess function that compresses only high frequencies (above 4Khz). for control of sibilance, an often ignored distortion problem when recording vocals. The C-128 also has a side-chain input that provides a way to control the compressor from an external source. I.E.,You could "duck" a musical track automatically by connecting a feed from a voice-over narration track to the side-chain jack.