Live Gain Staging: Avoiding Modern Distortion

TL;DR

Set your preamplifiers for peaks at –6/–3 dBFS (or 0 VU analog), leave headroom, centralize level at trim rather than at compressor/EQ output.

1) Express Method

1.1 Preamplifier Setting

Go up until you almost clip, then go down 6–10 dB.

Procedure:
1. Ask artist to play at concert level
2. Raise preamp gain until you see clip light
3. Go down 6–10 dB to leave headroom
4. Verify peaks are at –6/–3 dBFS

1.2 Normalization with Trim

Normalize channels around a common point.

Once preamp is set, use trim (or pre-EQ fader) to normalize all channels around a common level (e.g., 0 dB on fader).

1.3 Watch Bus and Matrices

Avoid adding sources that are already too loud.

Multiple sources added in a bus can create unexpected peaks. Leave headroom in each bus.

1.4 A/B After Processing

Compare at equal level after processing.

After adding EQ, compression, etc., compare with and without processing at equal volume to assess real impact.

2) Best Practices

2.1 Keep Headroom

Headroom is your safety margin for unexpected peaks.

In live sound, levels can vary. Leave 6–10 dB headroom to absorb variations and unexpected peaks.

2.2 Use Reduction Meters

Reduction meters (GR) are safeguards, not goals.

Don't aim for X dB reduction. Use meters to verify compression works, not as a goal.

2.3 Limiter at End of Bus

Use a limiter at end of bus if necessary (protection, not aesthetic).

The limiter protects against peaks but shouldn't be used as a creative tool. It's a safety.

3) Common Mistakes

3.1 Relying on Limiter to Fix Everything

A limiter cannot correct faulty gain staging.

If you rely on limiter to fix everything, you've already lost. Gain staging must be correct from the start.

3.2 Raising Make-up Instead of Adjusting Source

If you need to raise make-up by 10 dB, the preamp is poorly set.

Adjust preamp or source rather than compensating with compressor make-up gain.

3.3 Underestimating Multiple Bus Addition

Multiple buses added to master can create peaks.

Check levels of each bus and leave headroom in master bus.

4) Level References

4.1 Digital (dBFS)

• Peaks : –6/–3 dBFS (headroom)
• Clip : 0 dBFS (absolutely avoid)

4.2 Analog (VU)

• 0 VU = reference level
• +3 VU = maximum recommended level
• +6 VU = distortion risk

In digital, 0 dBFS = clip. There's no margin beyond. That's why headroom is crucial.

5) Quick Checklist

Before concert, check:

• ✅ Preamps set (peaks –6/–3 dBFS)
• ✅ Headroom preserved (6–10 dB)
• ✅ Trim normalized on all channels
• ✅ Buses and matrices checked (no overload)
• ✅ Limiter at end of chain (protection only)

Did You Know?

• 0 dBFS in digital = absolute clip (no margin like analog)
• Background noise increases if gain is too low (degraded signal-to-noise ratio)
• Headroom is your insurance against unexpected peaks and level variations

Additional Resources

• Understanding Compression in Live Sound - Use compression after good gain staging
• Proper Microphone Placement - Good placement reduces need for excessive gain