The system technician had spent four hours tuning the PA. Transfer function measurements, pink noise, careful EQ correction, proper delay alignment. The response was within ±2 dB from 60 Hz to 16 kHz. It was beautiful. Then the mix engineer arrived.

Within fifteen minutes of soundcheck, the mix engineer had applied +8 dB at 3 kHz on the vocal channel, +6 dB at 100 Hz on the kick channel, and a broad +4 dB presence boost on the guitar bus. The carefully tuned system response now had a 12 dB peak in the upper mids.

The system tech noticed and pulled 3 kHz down on the system processor. The mix engineer noticed his vocals had 'lost presence' and added another 3 dB. The system tech saw the response curve spike and pulled it back. The mix engineer boosted again. They were locked in an EQ arms race, each undoing the other's work, the frequency response oscillating like a sine wave across the afternoon.

By showtime, the system processor had -12 dB at 3 kHz and the mix console had +14 dB at 3 kHz on various channels, for a net result of approximately +2 dB — which is where the mix engineer would have ended up if he'd just left everything alone.

The Moral: System EQ and mix EQ serve different purposes. System EQ corrects the room and speakers. Mix EQ shapes the content. They should never fight. Use SonaVyx's transfer function to set and lock system EQ, then communicate the baseline to the mix engineer. Collaboration beats competition.