After a few weeks of practice on this, I’m pleased to report that I’ve at least doubled the number of bars (4/4 80 bpm) that I’m able to sustain, compared to where I was in my initial post (actually, it’s often more than double that). Breathing low in my diaphragm and keeping the breath supported made all the difference in the world.
I’ve been using something like the following in my practice:
- Play a sustained note with consistent tone for as many bars as possible (4/4, 80 bpm)
- Play a sustained note with consistent tone for as many bars as possible (4/4, 60 bpm) – record the number of seconds and aim for a little more each time.
- Play one octave ascending scales with each note getting an entire bar (4/4, 80 bpm). Goal is the entire scale (which I can now do pretty easily). When the top note is reached, descend in the same manner for as long as possible.
That routine has worked well for me.