I have messed with all these instruments, and one thing I know is that a mellophone is very easy to adjust to for trumpet players, wheras French Horn is quite a different thing. French Hornsare keyed in F where Mellophones are I believe Eflat. Trumpets are of course Bflat instruments. One reason Trumpet players can conver so easily in addition to slightly similar mouthpieces is the fact that the mellophone is fingered (dare I say this ) with the right hand like a trumpet, while the French horn is fingured with the left hand, right hand in the bell. the mellophone has a smaller bell and the hand holds the bell rather than stopping it. Hope this helps. Jim By the way, Spaw, i was and OSU guy for awhile before the bars on High street took their toll on my grades! Charlie Spahn was the band director then!