To tune up is to adjust an instrument until its pitches are right. Tune up before the concert, take a minute to tune up, still tuning up.
An orchestra does it together from an oboe's A, which is why that note opens every concert. The word also means to get an engine running sweetly, which is the same idea in another trade.
1phrasetune upTo adjust an instrument until its pitches are right.
“Give the strings a minute to tune up before you start.”
tune up is a phrase.
Practised in Music & Instruments