A festive mood prevailed at Carter Barron Saturday night for the opening concert of the amphitheater's Summer Series. When the speechifying by Mayor Barry and others ended and the music took over the nearly capacity audience awarded the musicians with strong applause.

Flutist Herbie Mann drew from diverse sources and generally avoided the commercial trappings in which he has often dressed his music. He employed echo devices and other electronic accessories in a program that touched on Ellington, shook with crisp Latin pulses, improvised on standard jazz ballads and returned often to the blues.

Mann's legato lines were punctuated by percussive bursts and on one funky piece he produced sounds indistinguishable from pizzicato violin. Guitarist Lou Volpe, utilizing wah-wah pedal and sophisticated slide technique, got down to the basics with a biting attack that left elongated bent notes hanging in the air. Drummer Buddy Williams' dry, muffled sound and cymbal drizzle was appropriately laid back and Frank Gravis had one hearing double with his electric bass cum bass synthesizer.

The Gregg Karukas Group, a trio with the leader at the keyboards, showed that they are capable of both flash and subtlety in an opening set that adhered to the character of jazz in an electric format.