Under JAR, ANY turbo-prop requires a type rating. There are no exceptions.
If it is multi-engine, the rating is restricted to a single type (although there might be combined ratings I don't know about ie on different variants of the King Air.)
If it is a single engine turbo prop it can be a generic one for all types from a single manufacturer. This is the "class rating for each manufacturer of single-engine turbo-prop aeroplanes" DJ Mixmaster refers to in his post. You still need to go to a TRTO to get this rating.
The weight limit of 5700 kgs which was mentioned in a previous post dates back to the pre-JAR days, when the CAA didn't use to make a difference between piston and turbo-prop engines when it came to ratings. This weight limit is now gone (your SEP class rating for instance has no upper weight limit, although the opportunities to fly a SEP above 5700 kgs are kind of limited anyway).
Hope this helps.
Regards
Gerard