Bits and pieces of the all-Bach program that William Yarborough and his American Chamber Orchestra brought to the Kennedy Center's Terrace Theater Monday night were quite nice. Stephen Hendrickson navigated the heights of the trumpet solo in the Second "Brandenburg" Concerto with smooth elegance and clarity. Soprano Rosa Lamoreaux turned in well-thought-out performances in her role in Cantata No. 140, "Wachet auf," and oboist Kathleen Golding had a wonderful evening, running through the twists and turns of her assignments with delightful agility and rhythmic security.

For the most part, however, it was a strangely unsettled and half-jelled evening. The small orchestra was slow off the mark and had trouble with upbeat entrances. There was some sort of misunderstanding between the cello and the rest of the ensemble in the last movement of the "Brandenburg" and a sort of rough-and-ready feeling about the performance of the "Peasant" Cantata that might have been appropriate to the broad humor of the story but not to the intent of the music. Baritone Jerome Barry had a hard time centering his pitch, and the 30-voice American Chamber Orchestra Chorus tried so hard to sound like a group of 300 that it projected more vibrato and vocal fuzz than text and line.

Yarborough brought a lot of this upon himself, choosing extremely fast tempos and then driving the music with an essentially featureless beat that did not give the performers much help.