WHEN an orchestra stages a composer's birthday celebration, it usually does it for lack of anything better. But a bicentennial is something that has to be recognized, and the Boston Symphony decided to celebrate the two hundredth anniversary of Beethoven's birth last week with a five day series of concerts, concentrating on the symphonies and piano concertos. The ailing music director, William Steinberg, brought in two distinguished conductors, Leonard Bernstein and Max Rudolf, and an equally fine pianist, Rudolf Serkin. As the week began, the prospects looked good.

The Festival did not turn out as well as it should have, with all this obvious talent, because the Symphony management and Mr. Steinberg did not allow enough time for production. The Orchestra has been tossed around among many conductors this season, partly because Steinberg has been ill, partly because he is not a full time resident. The variety of conducting styles to which it has been subjected is almost unbelievable, but the orchestra has held up well. Expecting an orchestra to put out a top flight performance of five different programs on five consecutive nights with a strange conductor and a strange soloist is absurd. The strangeness produced inferior results from all of the participants. Serkin's performances on the first few nights were wooden and incompatible with the orchestra, and the BSO, in its turn, was unused to Rudolf's distinctive style. Naturally, the performances did little to enhance the reputations of Serkin, Rudlof, BSO, or Beethoven.

The Concertos performed on Wednesday and Thursday evenings suffered the most. The First Concerto, on Wednesday, was static. The orchestra followed Rudolf in his highly correct and well paced interpretation, while Serkin played his own version, accenting different notes than the orchestra, making the humorous passages of the last movement so fast and racy that it sounded like Milhaud. The Fifth Concerto was almost unbearable. The Emperor has grown so familiar to the BSO that the orchestra dismisses it lightly. Only a few forte passages of the first movement and the opening of the second had any sort of inspiration, and the second movement fell apart before the end of twenty bars. The only redeeming features tof Wednesday and Thursday evenings were the performances of the Leonore and Coriolan overtures. Without a soloist to deal with, Serkin kept good control of the orchestra, and gave both of these well know pieces a crisp, satisfying interpretation.

BY FRIDAY night, Rudolf and Serkin were used to each other, and the quality of the performance was greatly improved. The Choral Fantasy in CMinor, Op. 80, probably the least familiar work in the whole Festival, got a lively interpretation. This unusual piece, which integrates piano, chorus and orchestra, seemed better prepared than any piece to date. The piano part sparkled, without any of the inference of keyboard exercises which Serkin had previously given. The Chorus Pro Musica, prepared by Alfred Nash Patterson, was in excellent tone, as might be expected from any vocal group which Patterson has conducted. After this opener, the night's program was well established. For the first time in the week, a piano concerto came off flawlessly. The Fourth Concerto had neither the over-familiarity nor the mechanical feeling which had characterized the Festival on the previous nights. For the first time, the listener felt some sort of satisfaction as the intermission began.

It was fortunate that there was an intermission after the concerio, because the version of the Fifth Symphony which followed was too overwhelming to take directly after another work. All of the usual deficiencies of the BSO were there-the winds (especially the clarinets) were abysmal, the horns frequently missed their cues, the unisons never came off in unison-but Rudolf managed to transcend all of the structural defects that have gotten into the orchestra in the past decade. Rudolf has a brilliant sense of pace and timing, and it displayed itself in this work. He skillfully constructed a great performance by avoiding most of the characteristic failings of his contemporaries. He never forced his pace, the way Leinsdorf did. He made the orchestra forget the influence of his predecessor, and got it to produce a clarity of tone, especially in the strings, which Bernstein might well have envied. The concert definitely belonged to Rudolf and the listener went away feeling that the aging conductor had made the BSO perform beyond its normal capabilities.

Once Rudolf had impressed himself so deeply on the Orchestra, Leonard Bernstein never had a chance of putting it into shape for the Ninth Symphony in one day. He could not be expected to get his soloists-Martina Arroyo, Lili Chookasian, Richard Lewis, and Thomas Paul-integrated with the orchestra, and he didn't. The first three movements were unsatisfactory, glossing over all the nuances of score which distinguish this work, and filled with muddy playing. The choral movement failed for lack of rehearal. The BSO recorded the Ninth with Leinsdorf only last year, and it was clearly influenced by this experience. If only he had been given an extra week of work, Bernstein could probably have produced a memorable performance. The fact that he didn't can be traced to the basic fault of this Beethoven Festival: the incredibly stupid idea that an orchestra can produce a completely different concert every night for a week.