How do I compose idiomatically for brass instruments?

Question

I'm thinking of composing pieces for small ensembles with varied instrumentation. Typically I compose on a keyboard. How do I determine if the musician can easily play on brass instruments such as trumpet, cornet and trombone the parts I write for them?

Answer 1

Don’t listen to the “sing” comparison. I’m a lyric tenor and there is no way brass player can play the melismas my voice can do. Nor can they jump around like me. Brass instruments are defined by their dynamic range in volume as well as their ability to play fast repeated notes. Keep this in mind when writing within their ranges. Also, the higher you write for them, the more you will exhaust them, so high notes should only be used with discretion. A good rule of thumb is to look at the orchestra like this: brass can play extremes in volume and fast repeated notes (double, triple tonguing); winds can play fast angular movement; strings can play lightning fast scales.

Answer 2

A general rule is 'if you can sing it' odds are they can play it. - But if you're a good singer this might get you into some problems. :P

A safer method is to generally not have CRAZY intervals and far jumps cause it'll be physically harder for them to breathe and change range drastically. If it's super slow - anything will go. But if its fast definitely keep the notes close.