By TIM GOPLERUD

Isaac Trapkus is the soloist for the Vanhal double bass concerto in the Juilliard Chamber Orchestra concert on April 12.

"Did you mean: Van Halen bass concerto?" So responds Google to my query regarding this year's double bass concerto competition piece. No, I didn't—but what an intriguing possibility. How about a set of variations on "Jump"? Right- and left-hand tapping techniques? And, since the double bass has no frets, wild pitch-bend effects galore sans whammy bar? Listen up, International Society of Bassists: how about a grant proposal? (Although Eddie Van Halen probably doesn't need the money.)

No, the Juilliard Chamber Orchestra concert on April 12 in Alice Tully Hall will instead be featuring a concerto for double bass by that rock star of 18th-century Viennese classicism, Johann Baptist Vanhal (also spelled Wanhal, Wanhall, Van Hal, Van Hall, or, sometimes, Vanhall), with Isaac Trapkus—a first-year master's student of Eugene Levinson and this year's bass-concerto competition winner—as soloist. (Also on the program are the Serenade for Strings, Op. 6, by Josef Suk and the Divertimento for String Orchestra by Bartok.)

Vanhal's life's story would make an inspirational Hollywood biopic: Born in 1739 into a family of bonded peasants in Bohemia, he gradually earned enough money from teaching music to buy his freedom and rose through Viennese musical society to become a respected colleague of Haydn, Mozart, and Dittersdorf, even playing cello in a string quartet with the other three. Offered a post as Kappellmeister, he refused it (perhaps because it too closely resembled the indentured servitude he had struggled to escape?) and became one of Vienna's first truly freelance musicians. In the middle of his life, he suffered a mental breakdown but recovered. Popular in his own time, his compositions fell into obscurity after his death in 1813, to be rediscovered centuries later.

The double bass has not been blessed with as large and venerable a solo repertory as its siblings in the string family. No bass concertos by Beethoven or Brahms exist, even though Brahms's father was a bassist. Haydn wrote a bass concerto which has apparently been lost. Mozart wrote a virtuosic double bass obbligato to his concert aria for bass voice, Per questa bella mano, but no concertos. Working against the use of the bass as a solo instrument is the diffuse, rumbling nature of the instrument's tone, making it difficult to hear over a full orchestra and relegating it in most minds to a supporting role. And, of course, its extraordinary size presents a much greater challenge in executing the kind of fleet passage work one associates with concerto solo parts. In spite of these obstacles, a number of lesser-known Viennese classical composers did write concertos for the bass which survived, including Dittersdorf, Hoffmeister, Sperger, and of course, Vanhal himself.

At the time this concerto was written, the standard for the number of strings and how they were tuned had not yet been settled for the bass, so the modern bassist faces a challenge not shared by other string players in deciding how works from this period are to be performed. This year's bass competition used an edition of the Vanhal in D major, but a version in E-flat major exists, too. A bassist in Vanhal's time would probably have used an instrument with five strings in the "Viennese tuning" of three thirds and a fourth, but some soloists of the period liked to tune up a half-step. The modern string bass generally uses four strings tuned in fourths. But for solo work, most bassists use a special "solo tuning" a whole-step higher than the standard tuning used in orchestras, placing more tension upon the instrument and giving it a more brilliant sound. So, to summarize: For this performance, the bassist will be playing in C but sounding in D for a concerto that also can be played in E-flat! (Confused yet?) These tuning issues can also mean that passages that would have lain easily under the fingers in the original tuning can be more awkward to play with the modern setup, posing problems for music editors and players alike.

Juilliard Chamber Orchestra Isaac Trapkus, double bass soloist Alice Tully Hall Thurs., April 12, 8 p.m. Please see the Calendar of Events for more information.

Mr. Trapkus, who hails from Davenport, Iowa, began playing cello in fifth grade but switched to bass because, he said, he liked the challenge of playing the larger instrument. While an undergraduate, he studied bass with Diana Gannett at the University of Michigan. A desire to work with New York Philharmonic principal bassist Eugene Levinson drove his decision to apply to Juilliard for his master's degree. "I was a little intimidated by his reputation, but the thing is, he knows what he likes, how to get it, and he demands it," he said. "He really holds you accountable for your playing."

Another challenge: At this performance, the orchestra will play without a conductor, as did the orchestras of Vanhal's day. "I'm no conductor, so hopefully the concertmaster will have my back, though the group certainly doesn't need me to keep them together," says Trapkus. "I'm most focused on being heard over the orchestra. Mr. Levinson told me to approach it like it was by Mozart, but perhaps you'll still hear my Czech ancestry coming through." Vanhal, who was born in what later became Czechoslovakia, would certainly have approved.

Tim Goplerud, database administrator and Web development manager for I.T., earned his master's degree in double bass at Juilliard in 1984.