Any relationship between the Joni Mitchell who played coffee houses and folk festivals in the 1960s and the Joni Mitchell who performed Tuesday at the Mann Music Center (Dell West) is purely coincidental.

A few years ago Miss Mitchell decided, literally, to jazz up her act. Lately she has been touring and recording with jazz sidemen, and one thing was very apparent at the concert - Miss Mitchell can not sing jazz very well and she can not play it at all.

Miss Mitchell's performance did not lack for energy, projection or sophistication. Indeed, she seems more assured on stage than she has ever been. The jazz musicians in her entourage, when they play without her, are quite stimulating.

The audience was respectful, though hardly enthusiastic. One could not help feeling that most of them would just as soon hear the Joni Mitchell of old, the Joni Mitchell who was one of the premier song-poets of the 1960s.