Leadpipe

This article is about the component of brass musical instruments. For the type of plumbing, see Lead pipe.
Piccolo trumpet in B♭, with swappable leadpipes to tune the instrument to B♭ (shorter) or A (longer).
Basic trombone anatomy
  1. tuning slide
  2. counterweight
  3. mouthpiece
  4. slide lock ring
  5. bell
  6. knob/bumper
  7. water key/spit valve
  8. main slide
  9. second slide brace/stay
  10. first slide brace/stay
  11. bell lock nut
Scheme of a French horn (view from underneath). #2: Leadpipe.

In a brass instrument, a leadpipe or mouthpipe is the pipe or tube into which the mouthpiece is placed.

For example, on the illustration of a trombone, the leadpipe would be between #3 and #4, the mouthpiece and the slide lock ring. In the illustration of a French horn, the leadpipe is #2.