It seems slightly odd in this age of computer plug-ins that there should still be interest in rackmount hardware for audio processing — but the demand is definitely still very strong, as the market clearly shows. In particular, modular racks of processors are becoming highly fashionable once again, with offerings from the likes of SSL (the X-Rack), Tonelux (the V8 Roadster) API (the Lunchbox), and other variations on the theme, such as the Rupert Neve Designs' Portico system. The latest addition to this genre is Audient's Black Series: a range of very high-quality and intriguingly innovative modules that can be mixed and matched to suit the user's requirements.

Audient's designer, Dave Dearden, has taken a fresh approach to the design of these 'Dark Art' modules, all of which are quirky and interesting in various ways. With a long career that has included working in some of the best studios around the world, Dave has acquired a wealth of experience of classic outboard processors — how they were designed, how they work, how they sound, and why engineers and producers like the sounds they make. Armed with that knowledge, he has designed the various Black-series modules not to emulate any specific classic outboard devices, but to be capable of delivering the kinds of sonic signatures that made classic outboard classic in the first place!

The bottom line is that the Black Series is all about the sound and the way the sound can be controlled, rather than yet another attempt to recreate the past. Having said that, of course there are a lot of familiar tried-and-tested design touches in the Black series, starting with the transformer-coupled, discrete, class-A circuitry, used throughout almost all the modules. The 4U frame size chosen for the Black series also affords the advantage of allowing slightly larger front panels than many competing products — which means there's more space for extra bells and whistles.

Amongst the unusual features on offer, the mic preamp includes Audient's proprietary 'HMX' harmonics control, which allows the user to determine how much harmonic distortion and colour is introduced to the signal. The equaliser module features an Overtone function adding some harmonic coloration, and a Glo mode that compresses the bass content to make it fuller and tighter. If that's not enough, there is also a Tilt switch to introduce a subtle lightening or darkening of the overall tone. The compressor module is an optical design with an 'overcomp' mode to introduce pre-compression and a dual-mode side chain, combining the best characteristics of both RMS and peak sensing.

Finally, the Black Series includes an A-D converter module that provides up to 24-bit, 192kHz conversion. The unusual aspect of this module is that there's nothing unusual about it — other than the superb quality, of course! In general terms, the technical specifications for all the modules are as you would expect of Audient products, and even seem to be rather conservatively rated in some cases.

The heart of the Black Series is, of course, the frame that supports the individual modules. The BR10 rack can accommodate up to 10 modules in pretty much any order the user requires. The 4U rack extends about 250mm behind the rack ears, and the separate PSU takes another 2U of rack space. Neither get particularly hot, so you could mount the PSU directly below the rack if you needed to.

The power supply is a substantial unit, with just an on-off switch on the front panel, and five yellow LEDs to indicate the correct operation of the various DC supply voltages: ±48V, ±18V and +12V. The rear panel carries a fused IEC mains inlet and an input voltage selection switch (230 or 115V AC), while the screened 1.5m DC output cable is permanently attached to the PSU, and terminates in a huge, eight-pole Neutrik Speakon connector. Although intended for complex speaker arrays, this connector can easily handle the voltage and current demands, and provides a secure locking connection, making it ideal for this application.

The back panel of the main BR10 rack unit carries a lot of connectors, since each of the 10 module slots is provided with three XLR connectors. These provide two inputs (A and B) and one output (C) — although the actual implementation varies with the different modules, as I'll explain later. A pair of 25-pin D-sub connectors is also provided, and these...