I play three notes on tenor trombone: Bb3, Bb2 and Bb1. They are all in first position. The first two notes are in the standard range of the trombone, while the last note is a pedal tone. This occurs when the instrument resonates at the fundamental, rather than the 2nd harmonic. Pedal Bb is relatively easy on trombone, but much harder on trumpet (I'm unable to do it, despite being proficient at trumpet and at a beginner's level on the trombone).
Author: Ovinus Real