The portion of fader travel (usually marked), about 10-15dB from the top, where console gain is distributed for optimum headroom and signal-to-noise ratio. As a starting point in gain staging, each fader being used should be placed at, or close to, design center.
DESIGN CENTER
Meaning of DESIGN CENTER in English
Guitar English glossary. Английский словарь гитарных терминов . 2012