MILES OF AISLES, Joni Mitchell and the L.A. Express, Asylum AB-202, $11.98 list: A Joni Mitchell performance is a fragile experience; her concerts have a personal impact which may be entirely different between people and days. It may not be a good idea to document that kind of experience – better, perhaps, to leave it a fleeting brush with an exceptional talent.

But they did it anyway, and “Miles of Aisles” has all the strengths of Joni Mitchell and Tom Scott’s L.A. Express, and all the weaknesses of a live recording.

As a sample of her songs from the source, it’s a fine set. As usual, though, she shortchanges her marvelous early work – only “Cactus Tree” from the first album is included – while some lesser but more recent material is included. Two new songs, “Jericho” and “Love or Money,” are added to the concert tracks. Hopefully, they will get more considered studio treatment later.

THE L.A. Express, when their accompaniment shows in the foreground, have the feel of her music, even as their jazz electricity transforms several songs. Consider, for example, the irony of the line “They paved paradise and put up a parking lot,” sung to electric guitar backing.

Her instrumental helpers, particularly Tom Scott on reeds and Robben Ford on guitar, flesh out many of Miss Mitchell’s leaner arrangements, needed in a large-scale concert hall setting, without sacrificing the intimacy and simplicity of phrasing that is the essence of her music.

They succeed, in all likelihood, because they are based in jazz (in concert, the group preceeds [sic] Miss Mitchell with a set which ranges from breezy froth to a very mental John Coltrane arrangement), and are used to the solo voice in their midst. In fact, they depend on it, work towards presenting it sympathetically.

THE WORK OF the L.A. Express here is important, because it is the only thing which really separates this set from Miss Mitchell’s past studio sessions. Joni Mitchell leading an electric orchestra is a recent innovation, hinted at on “For the Roses,” partially realized on “Court and Spark.” If this album is any indication, the next studio edition should be dominated by songs composed for this kind of ensemble.

Neither of the two new songs are destined to stand with “Both Sides, Now” or “Carey” in Miss Mitchell’s musical pantheon. They are, one suspects, creatures of their time and mood, love songs aimed at a lover or lovers known to Joni Mitchell very well, but to us not at all. Their messages may fit our relationships, maybe not. For a mass audience, they are another glimpse inside the songwriter, less revealing than some in the past.

“Love or Money,” the stronger of the two, is another of her show business love songs, like “Frse [sic] Man in Paris.” The song doubtless means a lot to Miss Mitchell (listen to the way she sings it), but it is couched in industry metaphor, and is hard to follow for the outside (i.e., consumer).

The band plays a more prominent part here than they do on some of the older songs, possibly a motive for including the new songs on an album otherwise full of remakes.

THE FAMILIAR tunes are balanced between effervescence – “Big Yellow Taxi,” “All I Want,” “A Case of You,” “Woodstock” – and introspection – “The Circle Game,” “The Last Time I Saw Richard,” “Blue,” “A Woman of Heart and Mind.” At one point or another, every mood expressed by Joni Mitchell on records is heard here. In that sense, “Miles of Aisles” is her first anthology.

Deft miking prevents Miss Mitchell from being obscured when the band hits full volume, a problem encountered during her live sets with the L.A. Express. The tracks, culled from six different California performances in March and August, are well balanced. The audiences get in the way on a few occasions, but generally there is an air of quiet good nature throughout the set.

For the real impact of these songs to get through in a live recording, you need less band, less crowd and more Joni Mitchell. “Miles of Aisles” is a good keepsake from this year’s tours, but as a picture of Joni Mitchell in concert, it just doesn’t work.