Which aspect of a mouthpiece would cause air in the sound?

[MountVernon]

Too open a throat or too open a backbore?

[Brassnose]

Looks like you like opening new threads with essentially the same topic by the minute. Would probably be better to stick everything together in one thread, I’d think people (and you) will lose track of what’s going on in those very closely related threads - essentially they all seem to be about airy sound. Sorry for being (too) direct but I don’t think there is much benefit in multiple parallel threads.
_________________
2019 Martin Schmidt eXcellence
1992 Bach 43GH/43
1989 Kühnl & Hoyer Model 15 flugel
1980/2023 Custom Blessing Scholastic C 😎
1977 Conn 6B
1951 Buescher 400 Lightweight
AR Resonance, Frate, Klier

[ek1986]

In my experience, a super open backbore will produce a cloudy almost airy sound with most sizes of throats.

A super open throat (while keeping the backbore on tight or medium) will produce a bigger core of a sound (darker) but it will also make intonation difficult if other mouthpiece components aren't adequately balanced.

[MountVernon]

Thank you, EK. Finally a worthwhile reply unlike the one above yours.

[Brassnose]

The fact that you got slow replies may indicate I was on target
_________________
2019 Martin Schmidt eXcellence
1992 Bach 43GH/43
1989 Kühnl & Hoyer Model 15 flugel
1980/2023 Custom Blessing Scholastic C 😎
1977 Conn 6B
1951 Buescher 400 Lightweight
AR Resonance, Frate, Klier