concert pitch

noun
1.
Music. a standard of pitch used for tuning orchestral instruments, usually established at 440 vibrations per second for A above middle C.
2.
a state of heightened eagerness, readiness, or tension:
Spring training had brought the athletes up to concert pitch for the beginning of the season.
Origin
1760-70
British Dictionary definitions for concert pitch

concert pitch

noun
1.
the frequency of 440 hertz assigned to the A above middle C See pitch1 (sense 30), international pitch
2.
(informal) a state of extreme readiness