The rise of machine learning in recent years has brought with it a new breed of plugin effects employing just one or two dominant central controls to steer a wide range of under-the-hood parameters that either wouldn’t make for a good user experience presented individually, or are just particularly well suited to macro-style operational oversight.

These so-called ‘one-knob’ processors are seen by many as heralding an AI-driven technological watershed in audio production, but whether or not that actually comes to pass, the efficacy and value of these ingenious virtual gadgets for the time-pressed professional can’t be understated. Here are some of our current favourites, some of which are completely free to download.

Slate Digital Fresh Air

Slate’s reductive aural enhancer plugin is built on unspecified “vintage exciter circuits and advanced dynamics processing”, the unseen parameters of which are brought together in a pair of knobs for near-effortless brightening and aerating of tracks, busses and full mixes. The two rotaries in question are Mid Air and High Air, each one dialling in sheen, presence and clarity within its particular spectrum; and notably, harshness just never becomes an issue, no matter how far they’re pushed. There’s clearly some very clever wrangling of EQ and multiband compression going on behind the scenes, and the results are invariably impressive, whatever the source material.

Another major element of Fresh Air’s appeal is that it costs nowt! No wonder our own PJ Gibbs made it his Software Product of 2020.

Sound Radix Auto-Align 2

Okay, so the ‘knob’ in this case is actually a button, but Sound Radix’s mixing miracle worker is the very exemplar of a software solution reducing a highly involved, time-consuming manual process down to a single user input.

Auto-Align exists to serve but one purpose: the temporal lining-up and phase-matching of multiple simultaneously recorded tracks – ie, drum kits, amped and DI’d guitars, orchestras, etc. When such recordings are out of phase, a ‘hollowing’ of the sound often becomes apparent, and this could previously only be addressed by nudging clips back into phase on the timeline by hand. Auto-Align, however, renders that tedious task a thing of the audio engineering past by making said adjustments for you, flawlessly, at the click of a button. Version 1 demanded the assignment of one track as a guide to be followed by all others before you could apply the process, but with the brand new Auto-Align 2, you just load the plugin onto every channel you want to straighten out, hit the Align button in any one of them and play the track for automatic grouping and analysis. Job done!

Softube Saturation Knob

The one-knob concept doesn’t get much more literal in its realisation than Softube’s minimalist plugin, which enables the imposition of three frequency-bounded flavours of analogue distortion through the twisting of its titular control. ‘Keep High’ is for fattening up basses, kick drums and other low-end signals without affecting high frequencies; ‘Keep Low’ is for dirtying up snare drums, hi-hats, top-heavy synths and the like; and ‘Neutral’ is your general purpose setting for broadband saturation. With the mode selected, all that remains is to crank the knob until the saturation indicator LED starts to light up, then take it as far beyond that point as you like – anywhere from subtle warming to all-out sonic destruction. Crucially, the output of the analogue modelling algorithms working their magic behind the GUI sounds every bit as convincing today as it did when the plugin launched over a decade ago, making Saturation Knob an obvious must-have.

Waves Clarity Vx

Available in regular and Pro versions, Waves’ AI-driven vocal clean-up plugin deploys neural networks to discriminate in real time between the human voice and any and all noises that could potentially get recorded along with it – air con, computer fans, traffic, rain, wind, engine noise, etc. Clarity Vx Pro features various parameters for honing the process, including six adjustable frequency bands, but the much cheaper Clarity Vx boils it all down to a single reduction amount knob, plus a menu for switching between its three situational neural networks, a stereo link toggle, and a Width control – simply turn the knob and hear that noise melt away.

Versatile and effective, Clarity Vx is a tool that anyone working with sung or spoken vocals needs to check out, and we suspect the vast majority of producers will find the uni-knobular non-Pro version more than up to whatever restorative tasks they might find themselves throwing at it.

UJAM Finisher Micro

UJAM’s Finisher series of plugins already make light work of puling up exciting effects chains under the guidance of a handful of macro controls, but the free Finisher Micro takes the idea to its logical conclusion for demonstrative purposes, and also stands as a thoroughly worthy offering in its own right.

For nothing more than 290MB of download time, you get a bank of 25 pre-made processing chains, stepped through (without clicks or dropouts, it must be said) using the next/previous buttons or automatable Mode knob, and brought to bear by the Amount knob. The chains span the creative gamut, from reverb- and modulation-based treatments to filters, distortions and more, and every one of them sounds great, positioning this as yet another no-brainer for anyone looking to accelerate their creative workflow without spending a dime.

Waves OneKnob series

Finally, our list wouldn’t be complete without Waves’ nifty collection of single-knob effects, which takes in distortion, ducking, compression, limiting, filtering, brightening, reverb and bass boosting. Since we’ve already covered them on Production Expert in so much depth, though, we’ll just point you towards the links at the bottom of this 2019 round-up, via which you can see and hear all eight of them in action under test conditions for yourself.

Are you happy trusting your signal processing to the governance of a single control? Share your thoughts in the comments.