Conductor Klemperer - a life in an age of musical titans. Otto Klemperer, His Life and Times, Vol. 1, 1885-1933, by Peter Heyworth. New York: Cambridge University Press. 492 pp. $34.50.

AT the time of his passing in 1973, Otto Klemperer was practically the last remaining member of an imposing fraternity of orchestral conductors whose careers and experience extended back to the beginning of the century and beyond. During the first dozen years of the LP recording era, these titans of the podium were heavyweight trading material for the major record companies, as versions of the classics - led by Wilhelm Furtwangler, Bruno Walter, Arturo Toscanini, Klemperer, Hermann Scherchen, Karel Mengelberg, Fritz Reiner, Sir Thomas Beecham , Ernest Ansermet, Pierre Monteux, and more - lined the record shops.

What a great many collectors of records since the 1950s may not know is that, although conductors like Klemperer, Leopold Stokowski, Dimitri Mitropoulous, and Scherchen recorded the masterworks of the ''three B's,'' these men in the first halves of their lives were unflinching champions of contemporary music. They incorporated the newest and most radical into their performances. The music lover who knows Klemperer exclusively as a conductor of the Missa Solemnis or Brahms's First will perhaps find this the biggest surprise in this first volume of Peter Heyworth's new biography.

Heyworth's book is a painstakingly assembled chronicle, the product of hours of multicontinental research that must have numbered like sands of the sea. Vol. 1 takes us from Klemperer's childhood and student days in Hamburg and Berlin, through the shaky days of the Weimar Republic's collapse and the onset of the Third Reich in 1933.

The early part of this century forced the majority of artists in Europe to move at least once, but Klemperer seems to have been particularly peripatetic. He did not (from a biographer's point of view) conveniently stay put in any position for a comfortable number of years, but instead moved about constantly in one conducting job after another, driven by restlessness, ambition, and idealism in his search for the ideal position of authority. A different opera house every season was practically the rate until his seven years in Cologne ( 1917-24).

So Klemperer boasts not only the usual collection of illustrious figures who appear in the story of any successful artist (Mahler, Strauss, Pfitzner, Schoenberg, Busoni, and Stravinsky, among them here), but also an endless parade of lesser figures in the German/Austro-Hungarian musical mosaic who, rightly or wrongly, have been left behind by history. Conductors Alexander von Zemlinsky and Oscar Fried (an associate of Mahler's), for example, come into view with Klemperer's early history, as do politicians like Leo Kestenberg, a post-World War I socialist active in German artistic affairs.

Klemperer's progress from young pianist and Wagnerite to a position at the center of the Bauhaus-period theatrical experiments in Berlin during the '20s constitutes the main story of his development. And it is interesting to see what a blend of modernist radicalism and respect for classicism Klemperer represented. While he was musical director of Berlin's Kroll Theater, he was surrounded by operas by Kurt Weill and Stravinsky and by designs by Schlemmer and Moholy-Nagy. Yet he (and Toscanini) probably refined more 19th-century bad habits out of classical performance practice than anyone else during that time. As a result he was often considered much too austere by traditionalists and not venturesome enough by modernists. Indeed, his career carried something of this misfit stigma for the rest of his life.

Heyworth, a British music critic and longtime music and recordings reviewer in The Times (London) Educational Supplement, the Observer, and The New Statesman, is also author of the 1973 book ''Conversations With Klemperer.'' I had been wondering for a few years why the history of a man of Klemperer's stature was so long in coming, and now it is easy to see the reason: Heyworth had to amass a prodigious number of notes, references, letters, reviews, and recollections, and he presents them in quite a readable manner. This first installment shows the impressive results.

Much is made in this work of Klemperer's supposed manic-depressive mental condition, and much of the macro-movement of his early career is interpreted through the guise of the extremely high and low moods he appears to have been subject to. This filtration is not obtrusive, however, and the volume as a whole presents a most informative account of the emergence of one of this century's most influential musicians, one whose feet were planted both in the present and the past, reminding us, perhaps, of what Modernism in its heyday was all about.