SPAN
by Voxengo · Utility · Spectrum analyzer
vst3s Score 8.9/10 · rated #5 of 10 metering & utility
A free real-time FFT spectrum analyzer with a stereo correlation meter and level metering (RMS, true peak, clipping, K-system and EBU R128).
It is used to see the frequency balance of a track or mix, compare mid and side content, and spot build-ups or missing frequencies.
Best for: Mix Bus, Mastering, Sound Design. Genres: all genres.
Keywords: built-in analyzer, metering, mid/side, broadcast, free, true-peak, full mix, bus processing, FFT-based, mastering, mix bus, sound design, utility, visual feedback.
What it does
SPAN is Voxengo's free real-time FFT spectrum analyzer, with level and correlation metering alongside the spectrum display.
- Spectrum: adjustable FFT block size, overlap and slope, with a secondary spectrum (for example mid against side, or a held reference).
- Channels: mono, stereo, mid/side and surround (5.1, 7.1) analysis, with grouping so one instance can show another's signal.
- Meters: RMS, true peak and clipping detection, K-system and EBU R128 loudness modes, and a stereo correlation meter.
- Display: several colour schemes and a customisable look.
It is free.
When to use it
SPAN is the spectrum analyzer most engineers start with, and many never replace it. It does one thing (show the spectrum, with basic level metering) and does it with more control than most free tools. It covers less ground in one window than Insight 2 and bx_meter, and where true:balance and Tonal Balance Control compare your spectrum with targets, SPAN just shows what is there.
- Best for: checking low-end build-up, comparing mid and side content, finding resonances before EQ, and matching the balance of a reference by eye.
- Genres: all; especially handy for bass-heavy electronic and hip-hop mixes.
- Look elsewhere if: you want target curves or genre references (true:balance, Tonal Balance Control) or loudness history over time (Youlean, Insight 2).
What producers say
SPAN appears near the top of almost every spectrum-analyzer list.
- eMastered (2025) listed it first among spectrum analyzers for its precise real-time display with peak and RMS readings.
- Integraudio called it "probably the most famous spectrum analyzer plugin available today".
- MusicRadar put it first in its 12 best metering plugins, highlighting K-system metering, the correlation meter and the mid/side overlay.
- eMastered: 9 Best Spectrum Analyzer Plugins
- Integraudio: 5 Best Metering Plugins For Loudness
- MusicRadar: 12 of the best VST/AU metering plugins
Where to buy
- Voxengo: Free
Tutorials and reviews
- How to Use Voxengo SPAN: EVERYTHING You Need to Know! (Futureproof Music School)
- How To Mix With a Spectrum Analyser - SPAN Tutorial (In The Mix)
- SPAN Spectrum Analyzer Tutorial - every mixing engineer needs this free plugin. (Audio Mountain)
- Voxengo SPAN Plugin Review and Tutorial
- [Voxengo SPAN] 2023 Walkthrough #1
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