Did some digging on Horn-u-copia, and it looks that is the original design, based on catalog illustrations. It's listed as dating from 1890s and was called the "American" model ("New American" for the 3v version).
Last edited by Fujiifilm; 01-11-2021 at 02:49 PM.
Reason: removed the conn loyalist info since Doug already posted it above.
Willson 2900 TA-1 Euphonium - Denis Wick 4AM
Yamaha YSL-643 Trombone - Bob Reeves BrassArk 5G "Gladstone"
Yamaha YSL-8440 Trombone - Denis Wick 5BS
VMI 3301S BBb Tuba - Schilke Helleberg
Past:
York Preference 3067 Euphonium - Denis Wick 4AL
Benge 165F Trombone - Benge Marcellus
Wessex BR140 Baritone - Denis Wick 6BS
F.E. Olds Special Trombone (ca. 1941)