Euphonium doublers: what is the euph part in Roy Harris’ 3rd symphony like? The only video I have found (Dallas Symphony) shows 2 tubas. Does the euph part work on either euph or tuba (& equally well?)? What line-up to do other US orchestras usually use?

I played it years ago in a community orchestra. There's not much to the part. It's OK on euphonium but it doesn't go particularly high and it'd be nice to be a more exact match with timbre of the tuba as it really is a "first tuba" part and not an independent instrument. I think F tuba is probably a better idea, but as a euphonium player I wouldn't turn down a chance to play it myself.

Thanks. Also useful if I have to fix low brass for it.

Somehow I missed this when it was originally posted. I have performed this on euphonium as well. Yes, it is written as a 1st tuba part, but I actually believe that euphonium is best for this work. The most significant part is near the end where the part is a link or transition from the trumpet/trombone phrases down to the tuba through dovetail writing. I think the euphonium is a better transition timbre between the sonorities, rather than going directly from the brighter brass voices directly to a tuba sonority. Of course, that's just my opinion.

The thing I remember the most about this work is the counting during the 3/2 sections. You must count very carefully because all the different phrases start on different beats. Hopefully, you have a conductor with clear conducting patterns!