Top 10 Tricks with Voxengo SPAN Plus for Accurate Frequency AnalysisVoxengo SPAN Plus is a powerful, flexible spectrum analyzer that many mixing and mastering engineers rely on for making fast, informed decisions. SPAN Plus builds on the free SPAN plugin by adding features like offline spectrum export, custom spectrum presets, larger FFT sizes, and additional display customization. Below are ten practical tricks to get the most accurate, consistent, and musically useful frequency analysis from SPAN Plus.
1) Choose the right FFT size for the task
FFT size controls frequency resolution and temporal responsiveness. Larger FFT sizes give finer frequency detail but slower response; smaller sizes show fast transients better.
- Use 4096–16384 for focusing on tonal content, mastering, and identifying precise resonances.
- Use 1024–2048 for general mixing and tracking when you need to see transient behavior.
- Use lower sizes (512 or below) for drums/percussion to see quick level changes.
Tip: Combine multiple analyses — a large FFT for sweeps and a smaller FFT for transient checks.
2) Set averaging and decay carefully
Averaging smooths the display over time and reduces visual jitter. Decay determines how slowly peaks fall.
- Use slow averaging for a stable, readout-friendly view during critical listening and mastering.
- Use fast averaging or no averaging when checking moment-to-moment behavior or spotting short-lived masking issues.
- For measuring sustained tonal balance, turn on long averaging and a slower decay so the display reflects the long-term energy.
3) Use spectrum snapshots and offline export
SPAN Plus allows you to capture snapshots and export spectrum data for later comparison.
- Capture a reference snapshot of a well-balanced commercial track in the same genre.
- Use the offline export to save CSV data and compare in a spreadsheet or DAW session for long-term A/B referencing.
- Use overlay mode to compare current mix against your reference snapshot and spot broadband differences.
4) Calibrate level and dB scale for reliable comparisons
Spectrum analyzers are only useful when levels are comparable.
- Ensure your monitoring level is consistent when comparing tracks; SPAN Plus reads relative levels — consistent playback level is essential.
- Set SPAN’s reference dB scale (e.g., -60 to 0 dB) so you’re not misled by zooming or autoscaling.
- Use the RMS and Peak displays appropriately — RMS for perceived loudness, Peak for transient headroom.
5) Use the correlation and stereo scope features to check mono compatibility
SPAN Plus includes a phase/correlation meter and stereo balance tools.
- Watch the correlation meter for negative values below ~0.0 — sustained negative correlation can indicate phase cancellation issues when summed to mono.
- Use the stereo balance and left/right traces to identify if low frequencies or critical instruments are panned unevenly.
6) Employ frequency masking detection with focused soloing
SPAN Plus has band soloing and zooming capabilities to examine specific ranges.
- Solo problematic bands (e.g., 200–500 Hz muddiness or 2–5 kHz harshness) and compare with other tracks or stems.
- Use narrow FFT and zoom to inspect resonances or problematic peaks, then sweep an EQ to find and fix offending frequencies.
- Combine soloing with bypass A/B of EQ to hear the perceptual change while watching the spectrum.
7) Use multiple instances on buses and master for context
Put SPAN Plus on individual buses and the master bus to compare context.
- Place an instance on the drum bus, bass, vocal, and the master to see how each contributes to the overall spectrum.
- Use the master instance’s overlay or reference to ensure individual adjustments move the aggregate in the desired direction.
- For sub mixes, watch low-end buildup by comparing drum+bass bus traces to the full mix.
8) Exploit custom presets and display settings
SPAN Plus supports custom presets for repeatable analysis workflows.
- Create presets for “Mix Check,” “Master Reference,” and “Drum Focus” with preferred FFT sizes, averaging, and dB ranges.
- Save display color schemes and trace thickness for quick visual familiarity across sessions.
- Use grid and ruler settings to mark important frequency landmarks (e.g., 80 Hz, 250 Hz, 1 kHz, 3 kHz).
9) Leverage keyboard/mouse workflows and automation
Speed up analysis with quick controls.
- Learn SPAN’s shortcuts and mouse behaviors (drag to zoom, right-click for menus) to rapidly isolate issues.
- Automate bypass or parameter changes in your DAW and watch SPAN Plus react — useful for verifying the effect of dynamic processing or transient shaping over time.
- Use snapshot comparisons during automation to capture before/after spectra for documentation.
10) Combine spectral analysis with critical listening and measurement tools
A plugin is only one part of the toolkit.
- Always A/B changes by ear after observing a spectral issue. Spectrum analyzers guide you to problems but don’t replace listening.
- Complement SPAN Plus with loudness meters (LUFS), true peak meters, and analyzer plugins that offer harmonic content or phase vectors for deeper diagnostics.
- For mastering, cross-check SPAN results with frequency reference curves from commercial tracks and trust both visual and auditory confirmation before committing changes.
Conclusion When used intentionally, Voxengo SPAN Plus speeds up diagnosis and improves objectivity in mixing and mastering. Combine appropriate FFT sizing, averaging, calibration, and snapshots with disciplined listening and other metering tools to turn SPAN Plus into a reliable partner for accurate frequency analysis.
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