How to Master Mixes with Voxengo SPAN Plus: Tips & Tricks

Voxengo SPAN Plus: The Complete Guide to Spectrum Analysis

What is Voxengo SPAN Plus?

Voxengo SPAN Plus is a real-time audio spectrum analyzer plugin used in mixing and mastering to visualize frequency content, phase, and loudness. It expands on the free SPAN with added features such as customizable display settings, multiple spectrum channels, advanced smoothing, and extended metering options—helping engineers make informed EQ, balance, and masking decisions.

Why use a spectrum analyzer?

• Clarity: Reveals problematic frequency buildups and masking between instruments.
• Balance: Shows tonal balance across the mix (bass, mids, highs).
• Verification: Confirms corrective EQ and mastering adjustments visually.
• Consistency: Helps match spectral footprints between tracks or reference mixes.

Key features to know

• Real-time spectrum display: Low-latency visualization with adjustable FFT size for resolution vs. responsiveness trade-offs.
• Multiple spectrum channels: View input, left/right, or mid/side spectra simultaneously.
• Smoothing and averaging: Short-term smoothing for readability and long-term averaging for track/tone reference.
• Overlap and block size: Control FFT block size (e.g., 1024–65536) and overlap to refine frequency resolution and temporal smoothing.
• Calibration and reference: Set dBFS or SPL calibration and import reference spectra for matching.
• Correlation and phase metering: Phase correlation meter and stereo vectorscope to monitor mono compatibility.
• History and persistence: Keep spectral history visible to analyze transient vs. sustained energy.
• Customizable scales and grids: Linear or logarithmic frequency scales, and adjustable dB ranges and gridlines.

Practical settings and when to use them

• Mixing — fast visual feedback: FFT size 2048–4096, overlap 50–75%, smoothing low (5–10%).
• Mastering — detailed resolution: FFT size 8192–32768, high overlap, smoothing moderate (10–20%) to visualize spectral balance.
• Analyzing low end: Use larger FFT sizes (16384+) and logarithmic scale to resolve sub-bass detail.
• Vocal or lead analysis: Smaller FFT (2048) for better temporal tracking of formants and sibilance.

Workflow examples

1. Matching a reference track:

   • Load both your mix and reference through SPAN Plus channels.
   • Set long-term averaging and higher smoothing to capture overall tonal balance.
   • Note frequency regions where your mix differs and apply gentle EQ moves or multiband compression.

2. Finding masking elements:

   • Solo the instrument and observe its spectrum against the full mix.
   • Identify overlapping peaks (e.g., guitar and vocal around 2–4 kHz).
   • Use subtraction EQ on the masking instrument or surgical boosts on the masked instrument.

3. Checking stereo and phase:

   • Enable mid/side view and correlation meter.
   • Look for wide low-frequency energy (can cause mono collapse); keep low end more mono if correlation drops below ~0.0.

Common pitfalls and how to avoid them

• Over-reliance on visuals: Trust your ears first; use SPAN Plus to confirm.
• Obsession with flat graphs: Different genres and instruments have distinct spectral shapes—aim for musical balance, not a flat spectrum.
• Ignoring temporal context: Use history/averaging to separate transient spikes from sustained tonal issues.

Tips and tricks

• Create and save presets for typical tasks (mixing, mastering, vocal tuning).
• Use spectrum overlays with transparency to compare versions quickly.
• Calibrate dB scale to your monitoring level for consistent interpretation across sessions.
• Pair SPAN Plus with a reference loudness meter when mastering.

Conclusion

Voxengo SPAN Plus provides powerful, flexible spectrum analysis tools that, when used with critical