Litmus

Litmus by Candela Audio is a processing analysis plugin that helps you hear, test, and verify what your plugins are actually doing to a mix. Insert it on a track or bus, load compatible VST3/AU effect processors into its internal analysis chain, and use Auto Gain, delta monitoring, blind A/B, spectral, harmonic, phase, latency, and loudness tools around that exact signal path.

Insert Litmus on a track or bus, load your favourite VST3 or AU processors inside it, and mix as normal – compression, EQ, saturation, clipping, whatever you like. Litmus constantly matches loudness in the background using ITU‑R BS.1770‑4 LUFS, so every tweak you make is instantly level‑matched, forcing you to judge tone, punch and clarity instead of being fooled by "louder is better". Alternatively, you can set Litmus to "Peak" mode instead of LUFS so you maintain your headroom while mixing.

Whenever you want to zoom in, delta monitoring lets you solo the exact sonic footprint of a plugin or chain – the added harmonics from a saturator, the "air" an EQ boosts, or the transient changes from a compressor – so you can really learn what each tool contributes to your sound. When it's time to commit, blind A/B mode anonymises chains, plugins or dry vs wet, tracks your votes, and reveals the winner only at the end, helping you pick the best‑sounding option without brand or UI bias.

Back up your ears with Litmus's built‑in spectral, harmonic, phase and loudness analysis, then collapse it back down and keep mixing – it's designed as an everyday utility that stays in your template, not a one‑off lab tool. Built with automatic latency compensation and crash‑safe scanning, Litmus runs as a VST3 (Win/macOS/Linux) and AU (macOS) effect and hosts your VST3/AU processors inside a single managed chain, with one license covering all formats and platforms.

Key features

• Internal analysis chain for compatible VST3/AU effect plugins, with up to 8 slots per chain.
• Per‑slot Auto Gain with ITU‑R BS.1770‑4 LUFS matching, three‑phase measurement, and 100 ms smoothed gain.
• Delta monitoring with wet/dry blend, dedicated delta gain, LUFS/RMS/peak readouts, and latency‑compensated alignment.
• Blind A/B engine for Chain vs Chain, Plugin vs Plugin, and Dry vs Wet with randomized labels, crossfaded switching, and vote history.
• Analysis toolkit: 2048‑point FFT spectral comparison, harmonic analyzer (fundamental + 16 harmonics, note + THD%), phase correlation and full loudness metering (momentary, short‑term, integrated LUFS, RMS, peak).
• Automatic and FFT‑based latency detection, crash‑safe plugin scanning, sidechain support and extensive DAW automation for hosted plugins.

Tech specs

• Formats: VST3 (Win/macOS/Linux), AU (macOS).
• Hosts: Any VST3‑ or AU‑compatible DAW (effects only).
• Audio: 32‑bit float, stereo I/O, optional stereo/mono sidechain.
• OS: Windows 10+, macOS 11+, Ubuntu 22.04+ (x86_64; Apple Silicon and Intel on macOS).