Arkady Shilkloper is not a member of a brass ensemble, he's more of a one-man show. He is a Russian horn player who took up the alphorn and is kind of amazing on it. Arkady is a virtuosic improviser on the instrument, often soloing with chamber orchestras, looping over himself, or simply playing alone. He loves the funk idiom, as the harmonic series on the instrument (lydian/mixolydian; major scale with sharp-4 and flat-7) serves funk harmonies well.
Jeff Agrell, with his interest in improv, has taken some influence from Shilkloper, advocating what he calls the "daily Arkady." This means to simply pick the horn and make things up constantly for five minutes, to see what comes out. Arkady said this method helped him learn to improvise. Here are some videos for your listening pleasure.
Arkady w/ chamber orchestra playing funk.
Arkady improvising alone.
More improvising alone (longer).