That would be the trombone, as it changes notes by use of a slide rather than valves.
From what I know it changes the notes for example from note Bb to C etc. (I might be wrong).
Brass instrument have valves to change the length of tubing that the air passes through. This allows the instrument to play different notes of various harmonic series.
The brass instrument that has no valves is the trombone. Instead of valves, it uses a sliding mechanism to change pitches, allowing for a smooth transition between notes. This unique feature distinguishes the trombone from other brass instruments that utilize valves to alter their pitch.
it was added more notes and it was extended
valves
valves
a trumpet is an instrument that is used in orchestra bands and is often used in jazz music. it is a brass instrument with three valves that change the pitch which will produce the notes.
The bass
Because three valves are all that is required to play the notes and harmonics required for its range. PS Some trumpets have four valves. This is to allow a change in pitch which extends the range of the instrument.
You can either press down or release valves , or you can adjust the slide on a trombone . You also can adjust the 'airspeed' to change the pitch without changing the valves or slide
The trombone has a slide that can be moved to change the pitch of notes rather than valves or keys that lengthen the tubing to change the pitch of notes like other brass instruments. And there are a lot more than 3 other brass instruments.