Hi all,
Yes, the original "ti" was indeed short for titanium, and that earlier tweeter was in fact a titanium/aluminum composite dome. Titanium is quite brittle and the aluminum was added for strength.
The latest tweeter in the M22s is pure titanium, which is lighter than the titanium/aluminum composite, and when I A/B'd the latest version with my 2002 M22 ti's, the differences are subtle, as Jay pointed out, but audible. The latest version seems smoother on brasses, vocals, sax and horns, with greater spaciousness and a deeper soundfield than the already excellaent soundstage of the "old" ti's.
It's only audible on really excellent recordings--big orchestral/choral works reveal the soundstage differences best. On a lot of other music, the two models are very close, with the added smoothness noted above.
In terms of on-going changes to the M22s and other models, I'd call them "subtle refinements", the only exception being the old M80ti, whose performance was much smoother after modifications to the crossover added as an ongoing production change in the summer/fall of 2003. It was still called a "ti" until 2005 when the "v2" designation was applied, along with numerous small mechanical changes to the binding posts.
Regards,
Alan
