After writing all that stuff, which still is valid, I think it may be all over complicating things.
Lately I've been telling people this:
-Simply sit down, exhale all your air. All of it
-Take a mouthfull of air (don't inhale, just open mouth, close mouth)
-Equalize
I if you can equalize - congratulations, you're doing the frenzel. If not, play around with the air and see what you can do to make it go in your ears
Once you master this, try it upside down in a pool.
Once you master that - your detph won't be limited by equalization for some time...
The key is to really exhale everything. That way you cannot cheat and do the valsalva...Go easy first, because it feels nasty, but if you manage to equalize, try going lower and lower in the air volume and see if it still works. If it works with completely empty lungs, then you got something. It doubles as a great exercise for how to deal with the feeling of being below you residual volume in deep dives and having to equalize. IMO panicy movements at that moment are significant cause of lung squeezes in divers reaching their "equalization limit". But doing this exercise helps you recognice those feelings and remain calm without actually diving deep.
