Hi:
i wondering what's different between Yamaha's marimba and Marimba one? which one is better or they both have weakest..because i am thinking to buy a marimba..

That's a hard question in general because it really depends on what you want. Perhaps http://malletjazz.com/database/ can help you a bit, but you really must listen and play the instrument before you decide.

Nat

Comparisons can be very subjective. However, there are a few objective differences in the sound. The Marimba One bars are generally shorter requiring them to be slightly thinner in the center. The Yamaha bars, being longer and thicker, require more force to get the bars vibrating. This makes it a bit more difficult to play at lower levels. They don't respond as easily and have a somewhat 'harder' sound.(Perhaps that's a bit subjective..)
They were designed around and for Keiko Abe's style some years ago. She used to break bars by the dozens on the older marimbas,and asked Yamaha to design a marimba more suited to her style and technique.
Also, the Marimba One bars in the low end speak faster than the Yamaha bars. This could be due to the design of the low end resonators.
The Kori bars also speak more easily and faster than the Yamaha and are probablly the most similar sounding instruments to Marimba One.
On the other hand, the low end Yamaha bars will not break as easily.
Bill Youhass