UnderTone Audio UnFairchild 1.0.8 — Mac version

Mixing engineers who reach for a vari-mu usually want glue, not a sledgehammer. The UnFairchild plugin — a collaboration between UnderTone Audio, Eric Valentine and MIXLAND — bottles the mkII hardware's push and pull and hands you the controls to steer it.

What do the time constants actually change?

Six preset positions copied from the original hardware give you tight to lazy recovery. The four variable settings let you set attack and release outside the classic shapes, which is handy when the preset constants feel too locked-in for a modern drum bus.

How does the THD knob affect the tone?

It's an overall control, not a per-stage tweak. Crank it and the midrange thickens with a soft, furry saturation that suits a vocal sitting too clean in a dense mix — you hear the weight before you clock the distortion.

What's the side chain and balance section for?

Side chain processing stops the low end from pumping the gain reduction, so a kick drum doesn't yank the whole mix down. The fine left/right balance trim lets you correct a stereo image that lists to one side without reaching for another plugin.

First days: setting the DC Threshold properly

Fresh install, stick it on a drum bus, and the needle might dance more than you expect. The DC Threshold control is the first thing to learn — it sets how much signal the compressor sees before it grabs. Crank it low and the plugin bites early, good for taming a wild snare. Push it higher and transients slip through with just a gentle squeeze on the sustain. On a vocal, I usually start with the threshold halfway and nudge it while watching the gain-reduction meter. You'll hear the sweet spot when the voice stops poking out but doesn't sound pinned down.

Feed-Back versus Feed-Forward: a quick rule of thumb

The hardware mkII could switch between these two detection paths, and the plugin keeps both. Feed-Back reads the signal after the gain reduction stage — it reacts slower, rounds off the edges, and feels more like a vintage vari-mu that's had a cup of tea before responding. Feed-Forward reads the input straight away and clamps faster. Try Feed-Back on a piano track that needs softening, and Feed-Forward on a bass guitar where the notes need consistent level. Swapping between them mid-session teaches your ears more than reading about it ever will.

Daily speed and stability on an older Mac

On a 2015 Intel MacBook Pro running Monterey, a single instance barely nudges the CPU meter — around three to four percent in Logic Pro with a full mix playing. Stacking eight or ten instances across a session pushes things closer to twenty percent total, which is workable if you freeze a few tracks. No crashes in three weeks of daily use, and the GUI draws without lag even when the transport is rolling. On Apple Silicon the plugin barely breathes hard; the ARM build loads fast and sits light on the system.

Mid-side toggling no longer collapses the stereo image

Version 1.0.8 rolled in without fanfare but fixed a handful of small gremlins that affected the MS processing mode. Earlier builds sometimes lost the stereo image when toggling between mid-side and left-right operation during playback; that's now sorted. The true bypass also received attention — popping noises that occasionally crept in when punching the bypass in and out are gone, which matters when you're A/B'ing in front of a client. No new controls, no flashy features, just a plugin that behaves itself better across long sessions.

Parallel compression without a second aux track

The wet/dry slider is a time-saver. Dial it back to around forty percent wet on a drum bus and you get the body of the compressed signal without losing the snap of the dry transients. No need to route sends, no need to duplicate the track, no need to worry about phase — the plugin handles the blend internally. For vocals that need presence but still need to breathe, sixty percent wet with a medium time constant gives you that forward midrange push while the dry signal keeps the consonants crisp. If you've grabbed a copy of the undertone torrent, this control alone might change how you set up a mix template.

MS mode on the master bus: what to watch for

Engage MS processing and the plugin splits the signal into mid and side channels, applying compression independently. It's brilliant for tightening a mix without collapsing the stereo width — squeeze the mid channel for punch and leave the side channel looser so the reverbs and room mics still bloom. One tip: check your mix in mono after tweaking. Aggressive mid-channel compression with the side channel left untouched can create a stereo image that folds up oddly when summed. The balance trims help you correct it, but catching it early saves head-scratching later.

• macOS 10.13 or newer
• Intel or Apple Silicon Mac
• Windows system also supported