Burgers, Hot Tuna's third album, marked a crucial transition for the group.

Until now, Hot Tuna had been viewed as a busman's holiday for Jefferson Airplane lead guitarist Jorma Kaukonen and bassist Jack Casady.

Their first album was an acoustic set of folk-blues standards recorded in a coffeehouse, their second an electric version of the same that added violinist Papa John Creach (who also joined the Airplane) and drummer Sammy Piazza.

Then the Airplane launched Grunt, its own vanity label, which encouraged all bandmembers to increase their participation in side projects.

Burgers, originally released as the fourth Grunt album, sounded more like a full-fledged work than a satellite effort.

It was Hot Tuna's first studio album, and Kaukonen wrote the bulk of the material, not all of it in the folk-blues style that had been the group's métier.

"Sea Child," for example, employed his familiar acid rock sound and would have fit seamlessly onto an Airplane album.

And "Water Song," one of his most accomplished instrumentals, had a crystalline acoustic guitar part that really suggested the sound of rippling water.

On the material that did recall the earlier albums, Hot Tuna split the difference between its acoustic and electric selves, sometimes, as on "True Religion," beginning in folky fingerpicking style only to add a rock band sound after the introduction.

The result was more restrained than the second album, but not as free as the first, with the drums imposing steady rhythms that often kept Casady from soloing as much, though Creach's violin made for plenty of improvisation within the basic blues structures.

All of which is to say that, not surprisingly, on its third album in as many years, Hot Tuna had evolved its own sound and music, and seemed less a diversion than its members' new top priority.