FOR THE most part, the University Choir remains an ornament to worship in Memorial Church. Several times each year they sing solo recitals. Last Sunday afternoon, they participated in a choral evensong that gave them a far larger role than the regular Sunday morning service, but within a sacred setting. The occasion was Reformation Day, and the program was built around Bach's Cantata #80, Ein feste Burg ist unser Gott ("A mighty fortress is our God").

All the performers caught the tricky rhythm at the start of the cantata. This is important for a building of Mem Church's acoustics where the lack of echo mercilessly exposes poor ensemble. The opening chorus has a beautiful trumpet part. It was played with a smooth and searing quality that cut right through the dense choral and orchestral texture.

John Ferris's conducting is an intriguing blend of strict execution with a romantic's respect for vocal line. Cadences were crisp and sharp, neatly framing the sections of the chorus. At the same time, Ferris did not hesitate to emphasize the beautiful chromatic lines.

Neither of the first two arias in Cantata #80 are exceptional pieces. David Buchner negotiated a painfully difficult bass part with good control. The string ensemble accompanying him was sharply attentive to dynamics: filling out in their tutti passages and quickly dropping back during the singers' sections.

More remarkable for its content and execution was the brief bass recitative, sung by Charles Hefling. Hefling sings with a baritone's lightness and ease. He gave intelligent emphasis to the text; were his range a tenor's, he would make an admirable Evangelist for the Passion settings. Ronald Coons, singing the tenor recitative, fared badly in comparison where his vibrato obscured his diction. He was much better, joined by alto Paula Shepard, in the duet which was the climax of the piece.

It is a shame that Carl Schlaikjer did not receive credit in the program listings for his oboe d'amore playing. It was a display of virtuoso caliber remarkable for its sensitivity of phrase and quality of tone. The instrument's sound filled the church in beautiful counterpoint to the alto-tenor duet.

The brass choir also played well, allowing for the inevitable slips with such instruments. The raw power of brass and timpani gives them a sound that instantly captures an audience's attention. The chorale in the middle of the cantata was a good display of the near-infinite variety of Bach's accompaniments. That they were invented solely to alleviate the boredom of the same old hymn tunes is forgotten in their individual splendor.

Ferris took the final chorale, which was sung by the congregation as well as choir, at a slow tempo. It brought the cantata to a measured, dignified close. The cantata was a moving experience, in part because of its contribution as a religious statement within the Evensong's framework, but more as a purely musical success.

THE BACH was only part of the Evensong's music. One of the anthems was Maurice Greene's Lord, let me know mine end. The Greene was almost funereal in quality and was lent a somber cast by the walking bass throughout the movement. The exceptional quality of the Choir's string accompanists was evident in their first entrance: they were even in their attack and in tune without the dead quality that comes from intonation obsession. The soprano soloists were well-matched and in good balance with the rest of the ensemble.

Far more interesting compositions were the Herbert Howells Magnificat and Nunc Dimittis. The Magnificat's Gloria section typified English choral music of the last hundred years. It was well-registered by the organist with enough reed mixtures to complement the thick vocal textures. The Nunc Dimittis, more restrained than the Magnificat, used extreme vocal ranges effectively at the end.

The only disappointments of the program were the Buxtehude setting of Ein feste Burg, an uninspired set of variations, and the postlude, the brilliant Sinfonia from Bach's Cantata #29 known in solo violin, solo organ, full orchestral, and Moog synthesizer versions. The Sinfonia was played brightly by strings and brass only to be let down by the organ. There was not enough bass registration to carry through the Church--in part, a design flaw of the Fisk instrument--but even the upper voices were too thin to compete with such a healthy orchestra. Coupled with a number of fingering lapses in an admittedly difficult part, the Sinfonia was still exciting--but it could have been much better.

With a Choir known for its purity of approach to performance, the soprano descant to the processional hymn, Ye Watchers and Ye Holy Ones, came as a surprise to more than a few listeners. There was a burst of sound as the last verse of the hymn exploded with brass and timpani joining the congregation and organ and the sopranos soaring off in their solo. This elaborate orchestration with descant is more familiar to St. Paul's Church than Memorial Church; it should be done more often here.

Outstanding singers and instrumentalists could accomplish nothing without intelligent direction. The Evensong was a great credit to John Ferris: the music was beautiful of itself and a legitimate contribution to the spiritual life of the Church. Rarely is the ministry of the word so ably complemented.