The bigger you get ...

In politics or pop culture the sentence ends in the familiar "... the harder you fall." But in classical music, it's more like "... the less room you have."

Violinist Joshua Bell Pittsburgh Symphony Andrew Davis, conductor Joshua Bell, violin What: Beethoven, "Coriolan" Overture; Gubaidulina, "Feast During a Plague"; Brahms, Violin Concerto; Strauss, "Till Eulenspiegel's Merry Pranks." Where: Heinz Hall, Downtown. When: 8 p.m. Friday and Saturday; 2:30 p.m. Sunday. Tickets: $19-$72; 412-392-4900. Listen in Josua Bell performs a transcription of Rachmaninoff's Vocalise for violin on the Sony Classical album "Voice of the Violin.

After years of performing and recording, top classical artists can play themselves into a corner, exhausting the core repertoire that sells the best. Especially with recordings, even superstars are rarely able to revisit that material, as Yo-Yo Ma did with the Bach Cello Suites. Most branch out within classical music, as violinists Itzhak Perlman and Pinchas Zukerman have with conducting.

But the vast majority of artists eventually mix in a little of that dirty little word, "crossover": Ma, with his Silk Road Project, and tenor Placido Domingo, with various songbook albums, to name a few.

These are the narrowing waters which star American violinist Joshua Bell has been navigating for several years now, and quite successfully, with the help of plenty of deckhands.

"There are a lot of chefs in the kitchen when it comes to my musical career," says Bell with a slight chuckle. "I have my manager, my European manager, some other managers, a personal assistant, my publicist and the record company executive. They sometimes have different agendas. So it is a fair amount of people who are involved in making these decisions. Of course, in the end I take responsibility for everything. I make my own decisions."

It's all about proportion. Keeping his credibility as a top-rate artist and a leading interpreter of the classics -- a career born from an explosion on the scene as a child prodigy -- means keeping the right balance of high-row artistic ventures and crossover ones.

"I was recently approached to do a Christmas special -- actually it ended up falling through -- but I was asked to do a duet with a pop singer," says the American violinist. "They wanted me to do a Christmas carol."

And what could be wrong with that? Well, it all depends. Bell considers these kinds of offers case by case.

"In the beginning, I was always so worried what the core classic people are going to think if I do this," he says. "After a while it was like, why do I care so much? If it sounds like fun to do a duet with James Taylor, why would I worry what people think?

"If you look back, [violinist Jascha] Heifetz did 'White Christmas' with Bing Crosby, and I don't think he worried about it for a second. And he starred in a movie, 'They Shall Have Music.' It's cheesy, but he did it and probably didn't think about it."

The results of Bell's branching out have only confirmed his resolve. He has had success performing on film soundtracks such as "The Red Violin" and "Iris," on crossover efforts such as Edgar Meyer's folk-tinged "Short Trip Home" and also with solo recordings such as "The Romance of the Violin" and "Voice of the Violin."

The latter are transcriptions for the violin of opera arias and classical melodies. "Voice" held the top Billboard spot on the classical charts for several weeks this fall. He has been nominated several times for Grammys in the Best Classical Crossover Album category.

Bell mostly performs the canonical repertoire of Beethoven, Sibelius, Brahms, etc., but finds that his impact can be just as great with the lighter material, such as when he performed on a track of Josh Groban's 2003 album "Closer."

"Almost every concert I get people going backstage or at my CD signing [saying] 'I didn't know of you, but I am a big Josh Groban fan, and now I am buying all your records.' I often get these people who say they have never been to a classical concert and you've opened up my eyes. It happens all the time.'

For the 38-year-old violinist, bringing these people into the fold is as important as playing Carnegie Hall, soloing with the world's best orchestras or being an artistic partner of the St. Paul Chamber Orchestra. "There is a big audience out there that is missing out that we shouldn't alienate."

Plus, Bell says playing a variety of musical genres keeps him from ever becoming jaded.

"If you sit and play the same five concertos over and over again, you start loosing perspective. For me, keeping things varied is really important. Playing with Edgar [Myer] and his bluegrass group, I just learned so much from those guys that I felt helped in my classical stuff quite a lot -- rhythm and improvisation. It inspired me to write my own cadenzas."

Bell will play his own cadenzas when he performs Brahms' Violin Concerto this weekend with the Pittsburgh Symphony, his first performance with the PSO since 1995. He also will accompany the group to play the work for a Carnegie Hall concert next week.

"It is possibly my favorite of all the concertos," he says. "I hate to use that word. But it has the depth and grandeur of the Beethoven, which is also my other favorite."

He hopes to never get too big for them.