APU Software introduces TrueGain

APU TrueGain is a powerful utility plugin which corrects for a fundamental challenge in audio engineering: a mix’s tonal balance changes depending on the listening level. By modeling the human ear’s frequency sensitivity at different Sound Pressure Levels (SPL), TrueGain allows you to audition and control your audio with perceptual consistency.

The core of TrueGain is its ability to perform “translation checks.” After a simple one-time calibration to your monitoring setup, you can use TrueGain to simulate how your mix will sound at different loudness levels, all without changing the actual volume of your monitors or headphones. This allows you to quickly check how the bass will hold up or if the vocals will become harsh in quieter listening environments, ensuring your mix translates reliably.

Alternatively, TrueGain can function as a perceptually-compensated gain control. In this mode, as you adjust the output gain, the plugin automatically applies the corresponding frequency compensation. This preserves the perceived tonal balance of your mix as it gets louder or quieter, making it an invaluable tool for your master bus, monitoring chain, or in live sound applications.

The frequency compensation is meticulously modeled on psychoacoustic research, featuring the modern ISO 226:2023 and ISO 226:2003 equal-loudness contours for state-of-the-art accuracy. For more of a vintage character, the classic Fletcher-Munson curves are also included. All filters are validated with rigorous tolerance requirements.

All gain and spectral adjustments are interpolated smoothly, with configurable smoothing times to control the responsiveness and help prevent any audible artifacts. To ensure maximum fidelity in any scenario, the plugin offers both linear phase and minimum phase filter types.

To provide detailed visual feedback, TrueGain includes a comprehensive real-time spectrum analyzer. It features configurable FFT sizes, window types, and time averaging. The frequency display can be switched between linear, logarithmic, or musical note scales, with an adjustable dB range and auto-zoom to help you focus on what matters.

"How does this relate to the Loudness Contour plug-in?"

TrueGainApplies the delta between Phon levels of ISO 226 or Fletcher-Munson
Specifically designed for loudness-compensated gain control
ContourApplies loudness contours directly (not deltas)
Supports more contours (includes those which don't have Phon-dependence)
Designed more for tone shaping / sidechain eq