The viol consort known as Phantasm is already internationally renowned for taking music as old as 400 years and giving performances of compelling vitality. Having them demonstrate their unique gifts Thursday night at UCSB's Lotte Lehmann Hall was made all the more fitting by the fact that the players were this year's featured guests of the Karl Geiringer Lecture series.The goal of the series is to present artists who not only produce great art, but illuminate it. Phantasm founder Laurence Dreyfus had lectured earlier in the day, and the performances spoke volumes as well. The joy of hearing the four players of Phantasm lies in the freshness and excitement of their interpretations. The instruments are a wonder: Dreyfus' treble viol looks from a distance almost like a violin, but it is held not under the chin, but between the thighs. The two tenor viols (played by Wendy Gillespie and Jonathan Manson) do look like miniature cellos, and although Markku Luolajan-Mikkola's bass viol looks like a modern cello minus the extension pin it shares a more slender elegance of shape with the smaller viols. All of them also have tones far less bright than modern string instruments, but also possess a sweeter, more intimate sound. The repertoire was as fascinating as the instruments, with half the composers more obscure than footnotes to modern concertgoers -- when was the last time you sampled Mico, Jenkins or Locke- The players of Phantasm know all these men and more as distinct stylistic personalities; there was never any danger of timbral monotony. But the enjoyment was greatly increased by Dreyfus's scholarly program notes. For all of the ensemble's charms though, the evening's most memorable moments came when the soprano voice of Geraldine McGreevy was intermittently added for three short sets of songs by William Byrd. She too dispelled old stereotypes about the vocal sound one expects in this Elizabethan music. Not a trace of hollowness or hootiness was heard, but a rich colorful and expressive instrument. McGreevy's nearly flawless diction and subtle gift for inflection nearly obviated the need to follow the printed texts -- but they were welcome, as again were the notes of Dreyfus. Several of the seven songs had meanings between the lines, whether political, satirical, or saucy.Closing the second set was 'Lullaby', a tender and charming work that alternates a lullabying chorus of Mary comforting the baby Jesus with narrative and reflection on the events following his birth. The final lullaby chorus kept the near-capacity audience hushed. The closing number of the night also served as the concert's collective title. 'Ye Sacred Muses.' A tribute to the passing of the towering Thomas Tallis, Byrd suggests that when Tallis died, a part of music died with him. The eloquence of the music and the performers was thoroughly persuasive. The final note died away, and an impetuous 'Bravo!' triggered a long ovation. The reward was a final Byrd lyric as encore, 'In Fields Abroad.'