- Check the rim. The rim is a part of the mouthpiece and varies in diameter. Rims that are larger in diameter allows more airflow, smaller rims tend to restrict airflow.
- Check the cup. Another part of the mouthpiece that you should look at. For beginners, a cup that is neither too deep nor shallow is suitable.
- Look at the backbore. Also found on the mouthpiece that is tapered in design. The degree of the backbore's cut or taper affects the quality of sound produced.
- Look at the shank. Another essential part of the mouthpiece that should be correctly fitted.
- Trumpets that are lacquered tend to chip off. Silver-plated trumpets last longer. Also look for a bell that has a medium flare.
- Check the leadpipe and make sure that there are no dents or damage.
- Check the valve pistons. The valves must be functioning well and responsive when you press it.
- Look at the valve casings. Make sure that there are no damage or dents.
Other Buying Tips:
- You must set a budget if you want to buy a trumpet. Good quality trumpets are more costly but will prove to be a smarter choice in the long run.
- Be very careful when buying a used trumpet. Unlike other musical instruments, the trumpet is very "personal" since it is played by mouth.
- When buying a trumpet, look and try different brands first before making your final decision. Pick the one that fits you comfortably.
- Check out your local music shops, newspaper ads and online stores when canvassing for a trumpet.
- Bring along an expert to try it out for you if you're an absolute beginner.
- Bringing along your own mouthpiece when trying out trumpets is not only smart but also a safe idea.
For reference, look at this illustration of the parts of a trumpet from Trumpet Exercises.