For frailing the set-up may have included using medium to heavy strings and a head that was more "plunky" sounding like Fibyrskin, or a real skin head. The action may have been set higher, as well.

If you want a bluegrass sound, you'll probably want to use light or medium guage strings, and get a brighter sounding plastic/mylar head, of which there are quite a few choices. The tension of the head can also affect whether it is plunky or brassy sounding. Other factors that affect the brightness of a banjo is the type of bridge, and the downward angle of the strings from the rear of the bridge to the tailpiece. In his book on setting up a banjo, Roger Siminoff(spelling?), says that for a bluegrass banjo this angle should exceed 12 degrees. Apparently the steeper this angle, the more downward pressure on the head, and the more brightness you'll get. Some of this you can do yourself. Have fun, experiment.