Re: Calibrated sets.... Definition?
The term sounds more precise than its common meaning. Calibrated generally just refers to a set with a stronger bridge pickup, to make up for the fact that the string motion is much greater near the neck than by the bridge.
Modern sets are paired this way, but until the 1980s most stock pickups were wound the same for all positions, so the neck usually sounded louder as well as much fuller. Having a bridge pickup that's wound a little hotter helps them balance better and helps the bridge sound a bit thicker than it would otherwise.