I just read on the Yamaha website that they now make a 5 1/2 marimba. From the picture, it appears to go up to a G83, and then it goes down to what looks like an extremely low A. I'm not exactly sure. Has anyone played on one of these?

Alex,

All it is is a 5.0 octave marimba with an extra seven bars on the top octave. It does not go any lower than a typical 5.0 octave instrument. Normally the marimba's top octave ends an octave below the top octave on a xylophone. All they have done is added seven more bars to extend it up to the "G" normally in the top octave on a xylophone. J.C. Deagan used to make instruments of similar range a long time ago, they just didn't go that low.

This link should take you to the YM5104-A specs pags:
http://www.yamaha.com/cgi-win/webcgi.exe/Specs/?gCPC00006MARIMBA+5104A

Hope that helps!
-Matt

www.coepercussion.com