"THE BANDS of the Potomac River Jazz Club" is a sprawling anthology, containing performances by 21 area ensembles. Some are defunct, others thriving, but all of them are infected with a love for early jazz (or some root or variation of it) and blessed with widely varying abilities to perform it.

So, as the song says, let's accentuate the positive. For starters, the two-record collection includes performances by some of the best dixieland and traditional jazz bands around, including Southern Comfort and Buck Creek Jazz Band. But more important than any one performance (which is what each band is allotted here) is the diversity of music and the spirit that binds these musicians together.

The album's selections range from obscure ragtime tunes to perennial banjo-driven favorites, from lively New Orleans jazz band recreations to Benny Goodman swing, from haunting blues to jug band skiffle. Along the way there are some fine numbers by the Manassas Festival Jazzers, Bill Whelan's Dixie Six, the Federal Jazz Commission and several less experienced bands. Like most samplers, this album has its ups and downs, but this time around the ups hold the decisive and winning edge.

However, there's nothing uneven about "Joplin/Blake: Ragtime Band," the latest release from the Peabody Ragtime Ensemble. This collection of engaging, often entrancing rag is wonderfully cohesive and exquisitely performed, capturing both ragtime's marching swagger and its delicate, melodic grace. While those qualities are best displayed by the septet during its performances of Joplin's work (thanks in part to Jared Denhard's inspired arrangements), the side devoted to Blake's compositions is nearly as enjoyable and in some ways much more revealing.

VARIOUS ARTISTS -- "The Bands of the Potomac River Jazz Club" (PRJC 001).

PEABODY RAGTIME ENSEMBLE "Joplin/Blake: Ragtime Band" (Peabody 74116-4). Peabody and other groups are appearing in the 1988 Jazz Jubilee, a benefit for the Leukemia Society of America, noon to midnight Saturday at the Sheraton National Hotel, Arlington.