McDSP KD1 Kinetic Drive

With the KD1 saturation effect, McDSP show that their analogue plug‑in system can deliver more than just dynamics processing.

McDSP’s Analog Processing Box has been on the market for more than three years now, and is building up a devoted following among mix engineers in the know. You can read our November 2019 review of the original APB16 for a full overview, but in summary, it’s a fiendishly clever device that takes the concept of digitally controlled analogue to its logical extreme.

The eight‑channel APB8 or 16‑channel APB16 connect to a Mac computer using Thunderbolt, and make their processing available through normal‑looking plug‑in interfaces. This gives the DAW user all the benefits of session recall and plug‑in automation, but the processing itself takes place in the analogue domain. Signal routed to an APB plug‑in gets sent out through a D‑A converter before passing through an array of analogue components, with the various APB plug‑ins configuring the analogue signal path in different ways so as to implement different processing characteristics. All of these are primarily based around manipulating the amplitude of the signal.

Super Saturation

The initial tranche of APB plug‑ins were all compressors and limiters, but we’ve always known that the system is also capable of deliberately introducing distortion. Several of the existing plug‑ins have saturation controls that allow the sometimes‑desirable side‑effects of overdriving analogue circuitry to be introduced. Until now, this has always been a secondary function, but with the new KD1 Kinetic Drive, McDSP have placed the APB’s saturation capabilities centre stage.

Like all the other APB plug‑ins so far, KD1 is free to registered owners of the hardware needed to run it, though you’ll need an iLok account to authorise it. Each mono instance uses up one channel of APB processing. The interface presents six rotary controls and three radio buttons. The Drive, Wet level and Dry level controls should need no explanation, and the wet/dry balance can be locked so that you don’t have to remember to reset it each time you load a preset.

The radio buttons are used to select your choice of three distortion circuits. As this is an analogue plug‑in, that’s not a metaphor: the circuitry really is reconfigured on the fly! The AWD circuit is broadly neutral, adding harmonic content roughly evenly across all frequencies. By contrast, FWD has a fundamentally treble‑centric sound, whilst RWD is darker. These are very general characteristics, perhaps akin in EQ terms to tilt or low‑Q shelving bands.

Two of the remaining three rotary controls work in tandem with the choice of circuit to further shape the tone of the processed audio. These Focus frequency and Amount controls dial in a more specific form of emphasis, applying up to 12dB gain at your choice of frequency between 40Hz and 4kHz.

The most interesting feature, though, and the one that gives KD1 its name, is a rotary control labelled Kinetics. McDSP say that this “controls analogue‑like behaviours, such as tube‑like compression and voltage supply reaction”. The Kinetics control runs from zero to 100 percent, and its effect is reflected visually on a bargraph meter labelled in Volts.

Light Touches

Some distortion effects major on extreme fuzz and dirt. Others explore the more subtle realms of light saturation and colour, and although terms like ‘crush’ crop up occasionally in the preset list, a little experiment suggests that KD1 is among the latter. If the source is recorded reasonably hot, high Drive and low Kinetics settings can produce outright distortion, but you’re not going to get high‑gain metal amp sounds from it. In fact, although the description might suggest that Kinetics models the ‘sag’ you get from valve rectifiers in guitar amps, KD1 definitely isn’t a guitar amp modelling plug‑in.

So what is it? Well, on one level, it’s a very cool way of manipulating the tone of recorded audio. By balancing the choice of circuit with the settings of the Focus controls and the wet/dry balance, you can achieve a surprising range of results. For example, you might assume that the RWD circuit is the obvious choice for bass guitars or kick drums, and in a sense it is, but the Focus controls make the other circuits highly usable on sources with lots of low‑frequency content. The broad treble emphasis applied by the FWD circuit can be paired with a more narrowly defined boost at 70 or 100 Hz applied using Focus and, at restrained settings of the Drive control, the result is not obvious distortion or saturation, but a subtle reshaping of the source that can make it sound more articulate and fit better into the mix. Or you could do the opposite, and use the RWD circuit to add heft to an anaemic kick drum whilst Focusing somewhere in the upper midrange to make it ‘knock’.

The general principle of using the Focus control to complement the tonal shift applied by the choice of circuit works equally well with other sources, too. For example, you can turn KD1 into a very effective treble enhancer by Focusing high up the frequency range and blending in just a little of the wet signal. Struggling to restore some lower‑midrange substance to a thin‑sounding electric guitar, I tried pairing the AWD circuit with a Focus boost at 400Hz, and the sound instantly acquired the richness and warmth I’d hoped for, with no hint of mud. I don’t think I could have achieved the same thing with EQ alone.

I’ve often thought that the APB system would be ideal for mastering engineers, who would love its precision and recallability.

As the effect generally remains subtle across quite a wide range of control settings, KD1 is also eminently usable on groups and on the master bus. I’ve often thought that the APB system would be ideal for mastering engineers, who would love its precision and recallability, and this plug‑in adds weight to that case.

Poetry In Motion

Digital emulation of analogue saturation has been getting better over the years, and as long as you left the Kinetics control at zero, you could perhaps get pretty close to the sound of KD1 using conventional plug‑ins. But Kinetics really does do something I’ve not heard in software. Its most obvious effect is to back off the distortion, making things sound smoother, but its real magic lies in the complex dynamic response it introduces. The KD1 manual uses the term ‘pumping’ to describe this, but to my ears, it’s more subtle and less straightforward than that expression suggests. Kinetics somehow introduces a sense of life and motion into almost any sound, but does so in such a way that you don’t really notice it doing anything until you bypass it. Some say that digital distortion plug‑ins tend to sound ‘flat’ and two‑dimensional — and next to KD1 with its Kinetics control turned up, they certainly do.

Creating a successful hybrid product requires both analogue and digital expertise. You’d expect the latter from a company that has been developing plug‑ins for several decades, but the APB system shows that McDSP are equally adept at analogue hardware design. If you’re thinking that only the golden‑eared will be able to tell the difference between analogue and digital in this day and age, a few hours spent auditioning these analogue plug‑ins will very likely change your mind. The distinctive quality of this saturation effect only reinforces that perception.