I never understood this. Isn't the whole point of a trumpet that it sounds brilliant and projects with clarity? If composers wanted to hear a dark sound wouldn't they write for horns instead?
People consider Bud Herseth to be one of the greatest trumpet players of all time. When I listen to him I don't hear a dark sound, I hear a big, bright sound with amazing clarity. Maurice Murphy sounded even brighter. Where are people getting this idea that trumpets should be dark from?