5 Parts Make a Whole : The far-flung Quintessentials practice in elevators and on the phone, then gather on weekends to voice unusual a cappella harmonies

Sometimes, Harvard graduate and business consultant Adam Button calls Paul Sagawa, a former classmate and now a rival business consultant, and sings to him on the phone.

Sometimes the singing gets so dynamic that a conference call results. The duo adds third-year UCLA law student Paul Luehr, inner-city high school teacher T. H. Culhane and fellow business consultant Jason Matthews--and the long-distance wires hum with yet another song.

And every weekend, the five reunite. Button flies in from his current assignment in Dallas; Sagawa, from San Jose, and Luehr, Culhane and Matthews drive in from West Los Angeles. Frequently, they sing at Sunday brunch at Santa Monica’s World Cafe. The quintet spends the rest of the weekend performing at private parties or doing stints at the Santa Monica Promenade. At the parties, recent hosts have included actress Connie Sellecca. At the Promenade, a recent patron was a homeless middle-aged man who ceremoniously threw in what he said was “51 cents of my money.” He urged his fellow audience members to contribute equally generously.

And so, The Quintessentials are helping to bring modern a cappella--five-part singing without musical instruments--to Southern California.

An offshoot of barbershop quartets and black spiritual groups, modern a cappella was born at Yale during World War II. From there, it spread through the rest of the Ivy League, then south to Duke and the University of Virginia.

As a cappella later headed west to Stanford University, all-women’s groups joined the formerly exclusively male domain--and competition to join became keener than ever. Recently at Princeton, 60 wanna-bes competed for five slots, Matthews said.

Los Angeles, with its emphasis on the car, rather than street culture, proved one of the last--and perhaps most formidable--frontiers.

When The Quintessentials first formed here six months ago, they found a distinct shortage of performance venues.

“We tried to sing on the Venice boardwalk, but the atmosphere was too seedy and disruptive,” Button said. Westwood, with its traffic jams and blaring radios, proved no better, and Century City’s semiprivate mall was legally problematic.

Santa Monica’s increasingly popular Third Street Promenade, however, with its echo-filled archways, heavy pedestrian traffic and lack of cars, proved ideal.

Soon after discovering the Promenade, The Quintessentials were, in turn, discovered by David Teck, who recruited the group for his restaurant.

“At its best, a cappella combines clever lyrics, beautiful harmonies and the voices coming together in a seamless blend,” Button said recently. “It’s the complexity of the singing that makes a cappella different from the rest.”

Rather than being blended together by a single arranger, a cappella is “polyphonic, each singer competing with the others for his own sound.” No synthesizers, musical instruments or recording mixes are in the way. Singers stand right in front of their listeners. Thus, “We’re able to achieve real contact with the audience,” Button said. “They think they can do it too; there’s nothing between us and them.

“When a lot of people here first look at us, their mouths hang open. They haven’t quite seen anything like this before,” he said.

Nor does the music always stop when he returns to work, Sagawa said.

Office building elevators have excellent acoustics, he said, virtually inviting a solo, ad-hoc practice session. Unfortunately, Sagawa will sometimes hold onto a note just a second too long, and the doors open before his mouth closes.

Or, sometimes in the middle of a business conference a song will pop into one of their heads, just waiting--no, demanding--to be conference-called to his partners.

Luehr, who thinks that his fellow law students sometimes take themselves too seriously, likes to take a break away from an occasional tort or contract negotiation by belting out a song from the ‘30s.

Culhane, who recently received a $3,000 Challenger Foundation Grant from Barbara Bush for innovative teaching techniques, has formed a Quintessentials offshoot, the Peristalsis Review. The Review teams Culhane and Button singing and swaying alongside Culhane’s Jefferson High School students, who each emulates the digestive tract at work. (Picture a class full of giant pythons up on their tails and swallowing their prey.)

Funded in part by the Challenger grant, Culhane has videotaped this performance and sent it to other science teachers in hopes of helping them make their lessons more lively.

Nora Reynolds, production coordinator for NBC-TV’S “Matlock,” was among recent brunch patrons at the World--and hired the quintet to sing for the TV series’ wrap party and its star, Andy Griffith.

Hiring a disc jockey, she said, “is the usual thing. But these guys are talented and special.”

Another fan is Emily Keety, 8, who regularly drags her mother over from Beverly Hills for the World’s Sunday brunch. Emily’s favorite musical groups, she said, are the Beatles--who disbanded long before she was born--and “these guys.” And her favorite request is “Poison Ivy”--because she once got it. Their repertoire includes oldies such as “Blue Bayou” and a vast range of love songs and folk songs.

Recent brunch patron Mark Nichols, a visitor from England, said he had “never seen anything like this.” He said the current English musical scene, with its emphasis on rap music, was “boring.”

“But this brings back the essence of the ‘50s, the sock hops and the big cars. They would do well in England.”

The Quintessentials perform at the World Cafe, 2820 Main St., Santa Monica, during Sunday brunch, 12:30 to 3 p.m. (310) 392-1661.