intransitive verb
1. : to limber up the vocal chords : sing out
the company tuned up and sang with goodwill — B.L.K.Henderson
2.
a. : to bring the instruments of a musical ensemble to a common pitch
the orchestra is tuning up and the concert is about to begin
b. : to make a tentative effort or a trial run
a few soapbox orators are tuning up near the bandstand — Winston Brebner