Odetta is one of two blues-folk greats playing in Cambridge this weekend, and if you have any sense of history or any conception of musical roots, you'll make your way over to the Performance Center on Sunday to learn what this business is all about. Odetta has been around for eons, and the years have only made her voice more deeply rich and her performances more moving. There's nobody else quite like Odetta; she'll only be in town for one day.

Dave Van Ronk is the other great one giving a local performance during the weekend, playing at Passim's until Sunday night. Van Ronk has been a dominant figure in folk for the past 15 years, and he's good at just about everything--old spirituals, jugband, political songs, love ballads and funning-around ditties. His voice is not the most esthetic thing around, it's sort of gravelly and rough, but his act is so smooth that you tend to forget and even to like the roughness of his utterances.

Funkadelic Parliment was kind of poohpoohed in these columns on Tuesday, but on further listening the error of our ways becomes obvious. The group is a big and brassy soul band that handles instrumentals better than any other R&B combo around. If you like Kool and the Gang-type music (how could you not), you'll love Funkadelic Parliament. They're playing through Saturday at Paul's Mall in Boston.

Miles Davis moves into Paul's Mall on Sunday, and this is a chance to see God before you get to heaven. For all intents and purposes, Miles has been jazz itself for the last decade or so. Almost any one of the young jazz men who is doing good things today learned his stuff from Miles, and there's a lot to learn from Mr. D. Miles can get into some pretty wierd stuff every once in a while, but what's wrong with wierdness? He'll be in town until Aug. 4.

The First Annual Beatle Convention, going on for the next three days at Boston's Bradford Hotel, sounds like a lot of hype but it also sounds like a lot of fun.