The Cantata Singers are one of those rare organizations that take their name seriously. In a concert of three cantatas of J. S. Bach, they produced a more professional sound than any group performing regularly at Harvard. The clarity they gave to every detail of polyphony, the precision of their runs and enunciation, and their rich, vibrant tone made listening to them a sensual pleasure.

But there were serious flaws in the way conductor Leo Collins used this magnificent choral instrument. Saturday's concert was just short of exciting because Collins' choice of tempos and articulation made the cantatas a little contrived, a little fussy.

The first, Aus der Tiefe (BWV 131), suffered primarily from excessively slow tempos. In the opening chorus, the slow pulse became divided, and the long tense lines tended to degenerate into series of disconnected fragments. The other choruses were more effective. Francis Hester's bass solo was a model of disciplined power, including some uncannily accurate duets with the oboe. Karl Sorensen's tenor solo, if a little monotonous, was consistently liquid and articulate.

The opening chorus of Bleib bei uns (BWV 6) featured a large number of choral trills. Although they demonstrated the chorus's virtuosity, the emphasis placed upon them distorted rather than heightened the expression of Bach's musical ideas. In the remainder of the cantata, Jane Struss' alto aria was lucid and delicate, if not overpowering, and Sorensen gracefully navigated the difficult tenor aria.

As if to make up for the slow tempos and truncated phrases of the other two cantatas, Collins startedWachet auf! (BWV 140) so fast that he almost left the orchestra behind. The opening chorus was a bit heavy, but it had an intensity that the earlier works lacked. Despite some rough spots, it was the most exciting chorus of the evening.

The heart of the cantata is an amorous dialogue between Jesus and a Soul, portrayed in two soprano-bass duets and a bass recitative. On the whole, the long and intricate duets received the meticulous dovetailing of voices that they demand. Unfortunately, Hester often overpowered soprano Marsha Vleck; at times she was almost inaudible. In the recitative Hester provided the most moving moment of the evening, molding the angular phrases into a lyrical declaration of love.

The final chorale epitomized the entire concert: tiny groups of words in the short phrases of the hymn were illogically separated from the rest of their clauses. But the chorale sounded so brilliant and majestic that these deficiencies could easily be forgiven.