Thinking of a sax-cello-bass trio he played in while living and working in Paris, reedist Avram Fefer conceived this string-heavy quartet for Shades of the Muse (CIMP). Despite the preponderance of lower-pitched instruments, however, it’s a light and mobile group, due in part to Fefer’s decision to use cellist Tomas Ulrich as a front-line instrument. Some credit also belongs to bassist Ken Filiano and drummer Jay Rosen, a crack rhythm section that keeps Fefer’s music snappy. When things go right, Fefer sticks to swinging, uncomplicated postbop and melodies informed by Middle Eastern scales. He has a fondness for unison lines and an even greater fondness for solo space-and he spreads out each liberally. There are some dead spots on the CD-the graphically notated, sluggish beast of the improv number “Gates of Baghdad” being a great big one-and some ragged play, but the collective charms outmatch the flubs.