The disclosure provides an approach for tuning musical instruments. In one embodiment, a tuning application determines frequencies of a series of notes played on a brass instrument, either with open tuning or with a valve pressed. As a musician holds a last note in the series and a tuning or valve slide is moved, the tuning application determines, based on a change in frequency of the last note and the measured frequencies of the other notes in the series, the change in frequency of the other notes. The tuning application then determines a compromise tuning that minimizes the total difference between the current frequencies of the notes and known note frequencies in a frequency table or previously tuned note frequencies if any of the notes were previously tuned. Upon achieving the compromise tuning, the musician or an actuator is instructed to stop moving the tuning or valve slide.