Concertmaster Zach De Pue's schedule sometimes requires his absence; that's when Kerr may step in. (Charlie Nye / The Star)

Alexander Kerr, principal guest concertmaster of the ISO, teaches at Indiana University. (Photo provided by Indianapolis Symphony Orchestra)

A recent Indiana University study measuring the Jacobs School of Music's impact on its home state reports that the school pumps $120 million a year into the Hoosier economy.

An interesting side note for local orchestra fans is that IU alumni make up a hefty share of musician rosters across the state. "The Impact of the Jacobs School of Music on the State of Indiana" reports that 29 percent of Indianapolis Symphony Orchestra players, for example, have IU degrees.

What the stats don't show is the impact of IU faculty members on area orchestras. The ISO has featured many faculty guest artists, and a professor is currently playing a key role with the orchestra.

Alexander Kerr, the 37-year-old former concertmaster of Amsterdam's Royal Concertgebouw Orchestra, has been teaching at IU for two years, and is the ISO's principal guest concertmaster.

Zach De Pue, a former member of the Philadelphia Orchestra, is the ISO's full-time concertmaster. But De Pue is out of town occasionally, touring with his crossover trio Time for Three, and Kerr usually stands in.

It's rare when Kerr and De Pue are at Hilbert Circle Theatre at the same time, but they will be this weekend, performing the Bach "Double Concerto." As the two prepared to play their first concerto together, Kerr shared a few thoughts about the ISO:

How have your experiences as concertmaster of the Cincinnati Symphony Orchestra and the Concertgebouw informed your ISO work?

I have worked with a lot of great conductors, (including) a lot who don't come over to perform in the U.S. -- especially (baroque) conductors. I can bring a fresh perspective to the school and the ISO. My relationship with Amsterdam was different from Cincinnati. It was much less hierarchical (in the Netherlands). There was a sense that, yes, I was the leader, but we made decisions together.

As a concertmaster, do you consider yourself a first among equals?

That is exactly my opinion.

How much do you work with Zach?

Actually, we speak quite often. We agree musically in just about every way. As long as we have the same musical vision, the group will play solidly together.

What will you be working on most with the ISO?

I think we're on a mission now to find certain styles. (ISO Music Director) Mario (Venzago) is very much involved in trying to create different styles. Playing Mozart is not like playing Brahms. How can we accomplish that together?

That's what I find my biggest role is there.

Indianapolis Symphony Orchestra

What: A Classical Series program, featuring J.S. Bach's Concerto for Two Violins in D minor, with Zach De Pue and Alexander Kerr.

When: 8 p.m. today, 5:30 p.m. Saturday.

Where: Hilbert Circle Theatre, 45 Monument Circle.

Tickets: $26-$63. Call (317) 639-4300 or go to www.IndianapolisSymphony.org