The shows alternate between the Community Arts Center in Wallingford and the Haddonfield United Methodist Church. "The church's Fellowship Hall has great acoustics," says Osman, 79, a retired marketing executive who lives in Haddonfield.
As he notes wryly, the borough is not generally perceived as a hotbed of jazz: "The image is Colonials and Victorians."
But in the 1960s, Haddonfield residents eager to hear their favorite music without having to travel to New York or Washington formed the core of one of the society's predecessor organizations.
And after it and similar groups in Bellmawr and Northeast Philly dissolved, 20 jazzophiles got together in a Cherry Hill home in 1988. They donated $100 each to book Hal Davis' Doctors of Rhythm into the Dutch Inn near I-295 in Gloucester County.
"It was a big success," Moorestown resident DeWitt Peterson, 84, the society's first president, recalls. "We were off."
The society since has grown to about 360 members, nearly half of whom live in New Jersey. Most are older, although younger people sometimes show up for the shows, which feature ragtime, stride, and boogie-woogie solo pianists, as well as classic Dixieland outfits such as the Atlantic City Jazz Band.
"Traditional jazz is not commercially viable," notes Catz, who lives in Ambler. "It takes nonprofits to make it work."
Nearly 200 people attended the July concert by Boston's well-known and well-regarded New Black Eagle Jazz Band at the church in Haddonfield. "That was a high point for us," Osman says.
The society and others like it offer musicians "very, very important" opportunities to be heard, says Franny Smith, a Haddonfield resident who plays banjo in the Atlantic City Jazz Band.
Says his sax-playing bandmate Bob Rawlins, who teaches music at Rowan University, "We play for an audience that is specifically there to hear what we have to give."
Catz, Osman, and 18 other volunteers keep the nonprofit organization in tune. The society has a website (tristatejazz.org), a newsletter ( The Strutter), and eminently affordable membership fees and ticket prices.
It's a lot of work but a labor of love, too.
"I really enjoy this kind of music," says Osman, who promotes the concerts online as well as with fliers he hand-delivers to local organizations.
"It's fun. It's upbeat," he says. "That's how I react to it."
Says Catz, "What really turns me on is the pleasure I see in people who come to the concerts and say, 'Wow.'
"We're providing them with something that might be lost," he adds. "Jazz needs to be heard in live performance. Something is being created on the spot."
Rawlins, who's 60 and lives in Clayton, says the society is part of a network that enables traditional jazz musicians to do something that once seemed impossible.
"People said, 'You'll never make money just playing jazz,' " he says. "Now I can."