Reverse Leadpipe Conversion:

This is where the top part of the main tuning slide is flipped around so the “male” tube is soldered to the lead pipe instead of the crook of the tuning slide.   This is done so the air column meets less resistance by falling off the edge of the inside tube instead of dragging on the ledge that is present when the tuning slide is in a “traditional” configuration.   This is generally done to give the horn a more open feel (more free blowing).   In some cases this may also improve the response of the instrument as well.   Certain manufactures make one way or the other standard on their horns with no option to have it done the other way.   Schilke makes all of their instruments standard with a reverse lead pipe while Blackburn makes his in the traditional configuration.   Both makers have sound reasons for their designs.   I’ve played horns that I felt to be flawless instruments made either way. Ultimately, it is a matter of a performers personal preference.