Learn to read between the lines... There are three parts to trumpet equipment: the mouthpiece that catches vibrations; the trumpet which simply amplifies them (Today, an old band mate that is still in high school asked if I still had my crappy Bb trumpet. I told him I did, that I still played on it, and it still sounds better than his "better" trumpet); and the embouchure (mouth, teeth, tongue, lips, and the way you use it all in general). All of the work of playing trumpet is in the lips and audio-sensory mind. If you are having trouble articulating, the problem is most likely in your tongue, its placement, and possibly air. If you aren't using a mouthpiece, it's hard to articulate on the trumpet; i.e. IT'S NOT THE MOUTHPIECE THAT MATTERS! Sometimes where you perceive a lack of coherency is really a lack of coherency in your own brain.