NO TUNE IN ALL OF music's history has been subjected to more manipulation by more composers than the headlong, tumbling 24th Caprice of Nicolo Paganini, which was originally written for unaccompanied violin and has since been heard in every musical medium form full orchestra to Moog synthesizer.

Paganini gave the precedent himself, writing 11 variations on the theme, and in more than a century and a half since he published it, his example has been followed by such heavyweights as Liszt, Brahms, Schumann, Blacher, Lutoslawski and (best known of all; better known than the original) Rachmaninov.

Now, in the footsteps of more than a dozen predecessors, comes Andrew Lloyd Webber, composer of Jesus Christ Superstar , who in his Variations (MCA 3042) demonstrates that there is still a lot of life and some unexpected dimensions in the old melody

The album, which hit the top of the British rock charts, is written for Webber's brother, Julian Lloyd Webber, a classical cellist, and a jazz-rock group called Colosseum II, which includes flute and saxophone (played by Barbara Thompson) as well as the usual keyboards (two players), guitar, bass and percussion.

"Julian made me compose it for him after I lost a bet to him about a soccer match," Webber said in an interview here. "To get even, I made it extremely difficult for him. I'd never done a piece without words before - my work has always been for the theater - and I chose the Paganini theme because of its virtuoso associations and because it's so recognizable you can do all sorts of things around it."

All sorts of things are precisely what he does in these 23 variations, which borrow techiques and style from classical, jazz and rock music indiscriminately. There is a variation that alludes obliquely to the lyric 18th-century variation of Rachmaninov, the best known section of this famous Rhapsody, and there is one that throws in a passing reference to the "Sailor's Hornpipe," a well known British folk tune. Elsewhere, Webber pays tribute to composers who might have used this theme but didn't (Gershwin and Prokoviev, for example) by writing variations in their styles.

In spite of this variety, Webber insists that the record is "not fusion - I'm trying to enlarge rock idioms, which must have on beyond the blues." He certainly manages that, but he has also given his brother a vehicle for some very spectacular cello-playing. Some parts of this 40-minute composition are better than others, but at its best it is brilliantly inventive and at its worst is easy listening.

It is hard to know exactly how to recommend this record, because its contents cut across many carefully erected and lovingly preserved barriers in musical taste. I have tried it out on a variety of friends whose tastes vary considerably and found rock fans largely enthusiastic, while for devotees of classical music it is a test of broad-mindedness. Those whose tastes are centered in the 19th century are able to enjoy some sections, but find others distressing; those with more eclectic and modern tastes tend to accept it completely.

Personally, I don't know what kind of music to call it, but I keep playing it over and over. The performance is on a virtmoso level, both from the soloist and the group, and the sound is good enough for any loudspeakers you put it through.