NEW YORK -- "I thought of Moby-Dick," says Jon Deak, "I thought of David and Goliath. Then someone just happened to mention 'Jack and the Beanstalk' and that clicked."

Deak earns his living playing contrabass for the New York Philharmonic, but for the past few years he has been earning a reputation as a composer, with more than 100 often wildly imaginative works to his credit and a stack of commissions to keep him busy -- "several orchestral works," he says, "about four years' worth of chamber music and a couple of video projects." At the moment, in the comfortable West Side apartment he shares with his wife, Jackie, and 4-month-old son, Nicholas, he is talking about "Jack and the Beanstalk," his new concerto for the National Symphony Orchestra that will have four performances beginning Thursday.

Jack and the Beanstalk? That's what the man said.

Deak has written some fairly conventional music -- a concerto for oboe d'amore and orchestra, for example -- but among the significant influences on his work he numbers John Cage, Spike Jones and Walt Disney -- not to mention the music of India, blues and funk. And he is best known for the strange and wonderful sounds he can make the string bass produce. He develops these sounds into musically intelligible structures that also have a strong narrative element. "Lucy and the Count," for example, tells the story of Dracula with the sound of flittering bats and squeaking hinges on doors or coffin lids. In "The Adventures of Sherlock Holmes," the double bass not only imitates, hauntingly, the distant howling of the Hound of the Baskervilles but the much less palpable sounds of mist creeping over the moors, a room filling with tobacco smoke and a death by heart attack.

Both these works and some others have been performed in Washington and enthusiastically received. One of the city's primary presenters of Deak's music is the 20th Century Consort, which is made up largely of NSO players, so "Jack and the Beanstalk" by Deak, commissioned by the NSO for its principal contrabass, Harold Robinson, is not such a strange idea after all. A composer who wrote a "Wind in the Willows" for the New York Philharmonic, with the contrabass taking the part of Mr. Toad and the violin section as Rat, should have no trouble at all spinning a story that has a giant, a cow, a hen that lays golden eggs and a magic harp.

"Jack will be the solo double bass," Deak says, "so of course the entire bass section has to be his mother, who is a major figure. The main problem is the audibility of the soloist. The bass looks like a big instrument, but it doesn't produce a big sound. It has a smallish kind of feel to it, a very human, personal, easily tromped-on feeling. But both Hal and maestro {Mstislav} Rostropovich wanted an unamplified solo and Hal has such a big, beautiful sound, and that dictated whole aspects of the piece.

"This piece has a medium-size orchestra, fairly small in the strings, but it has a decent wind complement to it. It is not used at the same time the bass is playing, but it provides the contrast that I want. Jack plays in a high register -- up in the cello and viola register -- very much of the time. This works out very beautifully for Hal, who has one of the sweetest upper registers I have ever heard anywhere. That gives me flexibility to put other sounds way below him or way above him -- out of the way."

Deak came out of the experience with his respect for Robinson confirmed: "I would write something and think, 'I would have a lot of trouble playing this' and show it to Hal and he would rip it right off. We worked together a lot; he's been up here a couple of times and I've been down to Washington three or four times."

A new concerto for contrabass is an event. There are only a handful in the repertoire, none really well known. In this century, they have been written by Hans Werner Henze, Gian Carlo Menotti and Serge Koussevitzky, who was a bass player before becoming the conductor of the Boston Symphony Orchestra. In previous centuries, they were written by Giovanni Bottesini and Domenico Dragonetti, both of whom played the instrument, and Mozart's friend Karl Ditters von Dittersdorf, who wrote concertos for nearly everything.

Deak, who already has enlarged the contrabass repertoire enormously, sometimes finds Deak the performer arguing with Deak the composer. "I wrote one solo piece early on for somebody else," he says, "and obviously I knew where all the notes should go and everything, but it was for somebody else. Then, six months later, I picked up the piece, because I had my own recital to play, and I thought, well, hell, I'll play this piece. But picking it up, I kept saying to myself, 'What is this composer writing? What is he thinking of? This doesn't sound good on the bass. Why is he doing this?' And then I would think, 'Oh, wait a minute, he means to finger it this way -- yeah, now it works.' There is a brain split -- I don't know which half does what -- maybe the right composes and the left performs? It's not that simple; but I had to look at this composer Deak as though he were someone else. It's weird."

Most American composers today support themselves by teaching, but Deak -- like NSO violinist Andreas Makris, whose Concertante will have its world premiere at the same concert -- prefers life in an orchestra. "It's full-time work, and hard work," he says, "but it keeps me grounded; it keeps me in touch with performances and audiences, and I need that to write my kind of music."

A native of the Midwest, he began to study music -- the piano -- in Gary, Ind., when he was 4. "I was no genius, but I loved to bang on the piano and imitate the sounds of nature." He didn't take up the double bass until he was a high school junior in Oak Park, Ill. "They had a wonderful orchestra," he says, "and I wanted to play in it, but I wasn't a good enough pianist to be the orchestra's accompanist or soloist. So I asked the director what instrument he needed and he told me to come around to a rehearsal and see what instruments the orchestra needed and what I liked and whether we could get together. I thought the bass section sounded good, but one boy dropped his bow and a girl broke out in tears before they even began playing, and the director turned and gave me a look -- so it was the double bass. It was love at first sight, as soon as I felt it vibrating. I wasn't the best player, but I had perseverance."