tone arm with 10gr mass with 15 gram weight cartridge?

With a well tempered you have variable damping to play with too, the raw resonance calculated for an undamped arm using the common formula won’t be the whole story.

http:// korfaudio.com/blog70

ok thanks everyone, i'll try to do my homework.
  

@stone1 , If you stick with arms on the lighter side, effective mass around 14 you can always add mass to tune the system. There are test records like the HI FI News Analog Test Record that have vertical and lateral resonance tracks that will give you a very good idea where you are. Then you add head shell weights until you get the lateral resonance down to 8 Hz or so. I like below 10 Hz as in my experience the bass is better. The published specs can only give you a ballpark idea of where you will be. There is enough variability to make accurate measurement of the pairing a much better approach. 

mijostyn
from my experience adding weight to the arm always harm somehow the sound 

You want to look at dynamic compliance @ 10 hz, that is the measurement that matters. Some cartridges only rate the cartridge at the 100 hz value. Generally you multiply the compliance numbers @ 100 hz by about 1.5x  to find the 10 hz compliance numbers. When looking at the resonance calculators, be certain to add in another 1 to 2 grams for the weight of the fasteners. As someone else mentioned, as long as you are able to balance the arm, free float, with the existing counter weight, then you should be fine. Otherwise, you will need a heavier counter weight. Below 11 grams is considered a low mass arm.