by Kathleen Klein

At 14, Joshua Bell became the youngest soloist to be featured in a regular season performance of the Philadelphia orchestra and he says he was ''pleased'' with his violin solo but it wasn't perfect.

His appearance with the Philadelphia Orchestra Friday is the top prize in a national competition to encourage young musicians.

Bell made his debut as a soloist in 1975 at the age of 7 with the Bloomington Symphony Orchestra and has performed with the Indiana University School of Music Orchestra, the Kalamazoo Junior Symphony, the Eastman Philharmonic and Cape Cod Conservatory String Ensemble.

After he finished his solo of Mozart's Violin Concerto No. 3 Friday, orchestra members voiced their approval and the audience applauded until he returned to the stage.

''I'm pleased,'' he admitted backstage, smiling for the first time at the bravos.

He said he made mistakes, but that did not mar his delight at performing under conductor Riccardo Muti.

''It's hard to make a perfect performance,'' he said.

Bell, who will play with the orchestra again on Saturday and Tuesday, admitted that before he began his performance he was a little nervous. He added, however, that once he started playing he ''forgot about being nervous.''

He said he tries to ''pretty much do what everybody else does my age,'' like play video games on his home computer and read mysteries when he's not taking lessons or practicing his violin four hours each day at Indiana University.

Bell took up the violin at age 5, at the suggestion of his pre-school music teacher, who ''thought I was something different from the rest of the class.''

A sophomore at North Bloomington High School in Indiana, he has played with top musicians before, ''but never an orchestra like the Philadelphia Orchestra.''