Best Stereo Analysis Plugins for Mac (AU, VST3)

Most producers mix in headphones or studio monitors, which naturally presents a stereo image. But a significant portion of listening happens in mono — phone speakers, earbuds, smart speakers, TV sets. A mix that sounds wide and immersive over headphones can collapse awkwardly when the stereo channels are summed to mono, losing elements that were panned heavily to one side or introducing phase cancellation that thins out the low end.

How Correlation Meters Reveal Mono Compatibility Problems

Stereo analysis plugins help you catch these problems before they reach the listener. The core measurement is the correlation meter, which expresses the relationship between the left and right channels as a value between -1 and +1. A reading near +1 means the two channels are nearly identical — a mono signal or something that's been very lightly widened. A reading near 0 means the channels are unrelated, suggesting heavy stereo widening or mid-side processing. A negative reading means the channels are out of phase with each other, which typically causes audible cancellation when summed to mono.

In practice, a finished mix that stays above 0.3–0.4 on the correlation meter throughout will generally translate well to mono. Elements that spend time below 0 — certain widened synth pads, stereo effects returns, some automatically-widened samples — are worth examining individually to understand what's contributing to the cancellation.

Vectorscopes and Lissajous Displays — Reading Your Stereo Field Visually

A vectorscope or Lissajous display adds another dimension to the analysis, showing the distribution of the stereo field visually. A roughly vertical oval means the signal is mostly mono-compatible with moderate width. A wide, nearly horizontal display suggests aggressive widening that may not translate well. Most dedicated stereo analysis plugins include both the correlation meter and a vectorscope, since they give complementary views of the same information.

Using a Stereo Analyser on the Master Bus Throughout a Session

WATCH from Silo DSP is a stereo analyser built for Mac with exactly this in mind — a clean correlation meter and stereo display in a minimal interface that doesn't get in the way. It runs natively on Apple Silicon in AU and VST3 formats, making it compatible with Logic Pro, Ableton Live, and any other major Mac DAW. It's designed to be the kind of plugin you leave on your master bus throughout the session so you always have a read on what's happening in the stereo field without having to switch windows or open a separate analyser.

For producers who are new to stereo analysis, the practical workflow is simple: drop a stereo analyser on the master bus, set a reference track you know translates well to mono playing alongside it, and compare the correlation readings. Over time, you develop intuition for what a healthy mix looks like on the meter, which makes it easier to identify and fix stereo width issues before you're done mixing rather than during mastering or after delivery.