TubeNet

Coming from a trombone player: what is the difference in construction between marching baritones/euphoniums/contras and concert horns? I know there's thicker metal and more bracing, but how are they built so that they project more instead of getting the warm and wide sound of a concert instrument?

Another factor is bore size and conicle progression. Concert horns are mostly larger bores where the marching tubas are smaler .689. They also stay more cylindrical until the final pass when they widen out to a 21" bell. The same comparison can be made from a miraphone 186/188 to a conn 56j or king 2341. The smaller bores allow you to project slightly better and tighten articulation. but are just slightly brighter. FWIW. But this can be hard to assess on a concert horn unless you feel inclined to lay on your back to play it.