The Washington Bach Consort opened its sixth season at the Church of the Epiphany yesterday afternoon with an all-Bach concert whose core was formed by three cantatas, two of them written specifically for performance on the 19th Sunday after Trinity (which was yesterday). The first of these, BWV 48, demonstrated music director Reilly Lewis' mastery of the Bach vocal idiom and his ability to mold the chorus andorchestra into a cohesive whole that balanced blend with clarity.

Contralto Beverly Benso sang with an appropriately dark but not heavy quality while tenor Darrell Parsons handled his solo movements with particular distinction. In Cantata 56 baritone soloist Craig Jessop sang his recitatives expressively but had trouble with projection; an oboe obbligato in Movement 3 was played with conviction by Janet Piez.

Violinist Joseph Gatwood separated these works with a brilliant performance of the second solo violin sonata. His technique, intonation and understanding of the intricate textures were so secure that he made the demanding work seem easy.

In the closing work, Cantata 34, Lewis' sure-handed control of rhythm, phrasing and balance gave a festive, dance-like quality that was supported by tasteful playing from the added trumpets and timpani. The obvious dedication and skill of all involved elicited well-deserved enthusiasm from the large audience.