Playing Low Notes
Low notes come down to one thing above all else: a slow, well-supported air stream.
Start with the setup. Sit tall with good posture and take a proper deep breath — really fill the lungs, not just the top of your chest.
Slow the air down. For low notes you want a slow, steady stream, not a fast blast. Imagine gently fogging up a window, or blowing softly across the top of a bottle. A slower air stream makes your lips vibrate more slowly, which gives you the lower pitch.
Open things up. Loosen your embouchure slightly and drop your jaw a touch — relaxed, not sloppy.
Support from underneath. Engage your diaphragm to keep the air moving steadily. You should feel your stomach muscles working — that’s what keeps low notes from sagging in pitch or fading out.
Get your slide or valves in the right spot. Lower notes need longer tubing. Take the time to find these positions precisely — a low note that’s slightly out of tune undoes a lot of the good work you just did with your air.
Low notes take patience. Work on your embouchure, your air support, and your positions consistently, and the low register will open up for you.