QUOTE(rosfrog @ Nov 8 2008, 09:26 AM)

I haven't heard you do it, so I'm not certain what the physical problem is exactly, but frequently in these kinds of situations (just after a strong crescendo), it helps a great deal to ensure that your jaw is relaxed (and preferably the lower jaw slightly back rather than forward), your tongue raised and spread at the back (as if you were trying to contact with your upper molars) but relaxed at the front (to avoid tongue root pressure on the larynx), then check your support and, maintaining an open throat (feeling like you're going to giggle the note, for example), just place the note in the same way you would make a sound if you were speaking very quietly, without whispering.
If you're above your first bridge, then add a tiny whimper to the sound and make sure you're not pushing with the airflow.
Hope that helps a bit ! If it doesn't, why don't you record it as it currently sounds (warts and all) and I'll bet one of us can find a solution for you.
Allan
Thanks for this Allan. I haven't tried it yet because I've just come back from a run and I'm drenched coz it's pouring out there, and I need a nice warm bath first. But I'm excited to experiment with what you say because I know I clench my jaw really badly, so I reckon that could be the main root of the problem. I'm trying to become more aware of it, but left to its own devices my jaw would win the gold medal in the International Jaw Clenching Championships.
Shall get myself sorted out here then give it a go and see what happens. Fingers crossed, and thanks again.
Ambs x