At the start of every show that Phil Ogilvie's Rhythm Kings play, a small glass piggy bank hangs from pianist and music director James Dapogny's mike stand. Many jazz bands of the 1920s and 1930s displayed a similar pig. The idea, Dapogny explains, is that "whoever made the last mistake had to ask for the pig, put some money into it, and have it hanging from his or her music stand as a badge of shame and dishonor, for having besmirched an otherwise perfect sound."

It's a small touch, but it indicates the lengths to which P.O.R.K. will go for authenticity. More significant, the ten-piece band duplicates the standard instrumentation of the early jazz big bands, plays mostly unamplified as they did, and even reads the same arrangements those bands played in ballrooms and on recordings.

But authenticity is not all P.O.R.K. is after. Sure, these musicians play with scholarly accuracy, but this was exuberant, lighthearted dance music, and P.O.R.K. really swings with that spirit. Formed four years ago, with a steady gig early Sunday evenings at the Firefly Club and concerts at many other venues and festivals, P.O.R.K. is finally releasing its first CD. We'll now be able to enjoy, whenever we want, the sounds to which our great-grandparents danced the fox-trot and the Charleston in the Roaring Twenties.

The CD kicks off with the title track, "Rhythm Club," the only tune not from the period. It's a Dapogny original, but I defy anyone who isn't a musicologist to distinguish it from the standards of the day. Dapogny's expert hands — playing and arranging — are evident throughout the recording, as is his encyclopedic knowledge of the music of this era.

There are numerous inventive, inspired solos here, and even some wonderful singing: check out Gene Bartley's velvet vocal on "If I Had You" or Dapogny's convincing blues gospel shouting on "Lawd, Lawd." But what stands out is the impeccable ensemble work. The reed trio of Andrew Bishop, Tom Bogardus, and Mike Jones, each playing clarinet and saxes, combined with the brass trio of Paul Finkbeiner and Ingrid Racine on trumpet and Gene Bartley on trombone, gives P.O.R.K. an enormous range of tonal colors and an ever-changing yet unified sound.

Chris Smith on tuba and Rod McDonald on guitar and banjo solo on only one cut — highlighting both how good they are and how perfectly they play their roles in the rhythm section the rest of the time. And Steve Fentriss, who is not yet old enough to buy a drink in any of the clubs in which P.O.R.K. appears, plays his kit like the reincarnation of Gene Krupa.

Until recently, most of this music has been available only on scratchy old seventy-eights. It always was great music, but the old recordings didn't sound like it. P.O.R.K., on Rhythm Club, sounds like it.