SL compressors are highly prized for their sonic qualities, and though every Duende ships with the EQ & Dynamics Channel Strip, and Duende Classic also includes the Stereo Bus Compressor, these no-nonsense plug-ins don't offer the kind of flexibility and functionality that many modern compression processors do. Enter X-Comp, then, which, like its frequency-shaping brother, X-EQ, features a clean interface with plenty of bells and whistles.
Ins and outs
X-Comp is immediately notable for its metering. Input and output meters are located on either side of the GUI, and each displays peak, RMS and dynamic history (showing the largest and smallest recent signal peak). Also included is a gain reduction display, but far more useful is the inclusion of an amplitude histogram named I/O Diff that shows the dynamics of the input and output signal set back-to-back. This enables you to see exactly what effect X-Comp is having - you can literally visualise, for example, a signal going into X-Comp with dynamics across the entire range and coming out of the other end with its energy mostly concentrated in the centre of the spectrum.
Moving on, and a familiar-looking compression law graph sits mid-screen, and below it the Bleed Through section. The latter enables you to specify frequency ranges to be filtered and routed past the compression stage. These filtered signals are recombined with the compressed signal at the output, with first order filters used to minimise colouration and ringing. You can determine the balance of dry/wet signal for either range, for further flexibility. This creates a really easy-to-use type of parallel compression that's great for situations where you don't want as much - or any - compression on the bass end, the highs or both.
An adjustable knee enables you to completely tailor the compression response, while a control dubbed Max GR gives the ability to determine the maximum amount of gain reduction that X-Comp can apply, ranging from 20-60dB. This lets the largest signal peaks slip through the compression net a bit and retain a little of their dynamics, giving a more natural sound, which could be desirable in certain situations, such as preserving some kick drum dynamics while still solidifying the sound. SSL reckon that this is similar to what happens in hardware optical compressors, which have an inherent gain reduction limit forced by the maximum amount of luminosity available from an LED!
X-Comp takes a bit of getting used to and, like X-EQ, it could benefit from an 'A to B' copy function. In the mix, it runs the gamut from the freaky effects of the SSL Listen Mic Compressor right up to 'brick wall with class' limiting akin to the legendary SSL Bus Compressor, although we should say that we couldn't get it to replicate either one exactly. It also throws in many subtle choices and masses of options, delivered with sweet-sounding analogue-style tone, and is enjoyable to use, once you've got the hang of it.
While it's questionable whether the current 'X' range goes far enough on its own to persuade us to buy a Duende, they're hopefully the first of many designer audio tools from this stable, and for some of us, the SSL brand is a proven mark of quality that's incredibly hard to resist...