Just added release The Sacred Trombone , tracks 3 & 7 of which are of works written specifically for the then (<1991) newly-constructed alto trombone (recorded on Conn 36H model). From earlier times, the alto trombone was customary until the valve trumpet had it “pushed down” to become the higher one in a tenor trombone pair. It is not a new thing but revived with HIP movement; and the Conn 36H has a trigger for lowering fundamental.

Earlier tuning, I think, was F and sometimes E-flat, while modern altos meant to be modern are E-flat.