Paul Silverthorne first asked his parents for a violin when he was 4, and he got his wish at 5.
But once he grew to almost 6 feet tall — with unusually long arms and fingers — it started to cramp his style. While studying at the Royal Academy of Music in London, he traded in the violin for its big sister, the viola.
"It changed my life completely," said Silverthorne, who has served as the principal violist of the London Symphony Orchestra since 1991. "Instead of just a good musician, I found an instrument that really was my voice."
Over the course of a long career spanning chamber music and solo appearances, he has commissioned many contemporary works for his instrument.
"There isn't much written for the viola, so if you didn't take an interest, you would really limit yourself," said Silverthorne, who also serves as principal violist of the London Sinfonietta, a contemporary music ensemble. "The viola has more mystery, and I think composers really respond to that, particularly in this century, when everything has been said on the violin that can be said."
This weekend, Silverthorne will perform the world premiere of Behzad Ranjbaran's Viola Concerto with the Santa Rosa Symphony, which commissioned the work.
The program, led by Music Director Bruno Ferrandis, begins with Alexander Borodin's Polovtsian Dances from the opera "Prince Igor" and culminates with Nikolai Rimsky-Korsakov's sparkling "Scheherazade."
Before flying out to California, Silverthorne and the composer will give a seminar on the concerto at the Juilliard School in New York. Ranjbaran will also be in attendance at the Santa Rosa concerts.
During the past year, Silverthorne has been collaborating with the Iranian-born composer on the work, sending him little suggestions on technical issues. More recently he's been getting the concerto deep into his hands and head, through daily practice.
"It starts with a long, sinuous melody, with lots of Eastern influence, treated in a very Western, traditional way," he said. "And it builds up the tension."
The second movement takes a dark and expressive turn, exploiting the soulful sound of the instrument, which has different acoustics than the violin or cello.
"The viola has to work with a smaller body than is acoustically ideal, and that's why it has a different character," he said. "There's a vulnerabilityand a human sound to it."
The last movement of the concerto is a classic finale, with the viola madly dancing through virtuosic passages.
"It's pretty fast all the way through, with no respite," he said. "This should be a lot of fun."
What unites the concerto is a common theme that returns in different tempos: moderate in the first movement, slow in the second movement and at breakneck speed in the finale.
"He uses all of the different registers very well," Silverthorne said. "There's some passionate stuff low down, a lyrical middle range, and the viola floats high above the orchestra as well."
Silverthorne's viola is on loan to him from the Royal Academy of Music, where he studied. He's been performing on it for the past 30 years.
"It was made by The Brothers Amati in 1620," he said. "It's larger than most violas today."
Despite its size, Silverthorne plays the viola in a fluid style that he learned through the "Alexander Technique," named after Frederick Alexander.