If it seems odd that a recording of rather obscure tangos became one of the best-selling classical albums of 1982, consider for a moment the strange evolution of "The Tango Project."

"This really goes back to the ragtime revival, in a sense," says the album's producer, Eric Salzman, who is sitting barefooted in the kitchen of his basement apartment in Brooklyn Heights, along with Michael Sahl, the album's arranger.

"I had a New Year's Eve party here in the '60s," says Salzman. "At the time I was running a radio show on WBAI and had discovered some ragtime recordings. Josh Rifkin lived across the street. He heard them, and I guess you could say the rest is history."

Rifkin's album, "Scott Joplin Rags," started the popular interest in ragtime and was indirectly responsible for the soundtrack of "The Sting" and E.L. Doctorow's novel-turned-movie, "Ragtime"; in January 1975 the record, on the Nonesuch label, became the number one classical recording in the country; last month "The Tango Project" also became number one, the first Nonesuch record to do so since Rifkin's.

"There's always been an interest in thematic concepts at the label," says Salzman. "In 1969 I was in Buenos Aires, teaching a course in multimedia at the invitation of composer Alberto Ginestera. I heard some tangos down there, and I thought, 'this might make an interesting record.' "

Not long afterward, a friend of Michael Sahl's came back from Argentina with some cassettes of tangos. Now both men were intrigued. They'd been doing projects together since 1955, when they met as graduate students in composition at Princeton while studying under Roger Sessions and Milton Babbitt. Although well respected as a music critic and the producer of an album of obscure Kurt Weill songs with singer Teresa Stratas, Salzman's major interest was in directing and writing multimedia works; Sahl had written five operas with Salzman, including "Civilization and Its Discontents," winner of the Prix Italia, although he was probably most widely known as an arranger and pianist for Judy Collins.

"The music business is very incestuous," says Sahl. "When we got into it in the '50s, it was really a small business, with a lot of independent record companies."

"I went to Forest Hills High School with Mike Stoller half of the Lieber/Stoller team that wrote "Hound Dog" and dozens of other classic rock 'n' roll tunes ," says Salzman. "We all wound up part of the Tin Pan Alley music team.

"Anyway," says Salzman, "in the '70s, I had organized a music theater ensemble. One of the members was an accordianist, Bill Schimmel. He went to Juilliard and pretended that he didn't play the thing, because the accordian isn't considered a real instrument. It turned out that he knew the entire tango repertoire. Said he knew 2,000 by heart. I believe him. The guy has a photographic mind."

"Phonographic mind," says Sahl.

"So, we thought, let's do a tango record. We started looking around for a composer like Joplin to focus on, but it didn't turn out that way. There didn't seem to be one great writer. So we decided on a style of band, the equivalent of a great jazz band, and settled on Julio de Caro, a violinist who had the trio at the Cafe' la Paloma. The major problem was finding someone who could play the violin parts. The style of playing of de Caro has almost totally disappeared. There are two pieces of trouble. One is a technique called portamento, which means slipping and sliding from one note to another on the same string. It's abhorrent to modern players, considered slushy and flashy. But, you see, de Caro isn't slushy. He's got tone and soul. He doesn't go too high or too low.

"The other trouble is timing. In tangos, you have to play against the time, which isn't something most modern players can do. We finally found this fellow Stan Kurtis, from Juilliard, who was interested in tangos but didn't know anyone else who was."

The album, which was taped digitally, took only 17 hours to record. The critical response was almost universally positive: "Drop a needle anywhere, and you will hear, as distinct, strange, various, and Circean as the ocean in a shell the gallantry, melancholy, and panache for a form as protean and infinitely renewable as the sonnet," wrote High Fidelity magazine.

"What we've done here," says Sahl, "are early authentic Argentine tangos. This is very sexy music. The white slave trade went Paris-Marseille-Buenos Aires. The tango went back in exchange from the bordellos of Buenos Aires. It was a very hot dance which involved hip contact. First it was done by pimps and whores, then it was done by johns and whores."

And with this, Sahl leaps from his chair and begins to glide around the kitchen, explaining the dance form, as he calls out its rhythms: "Ba-DUM-bum-bum-bum. . .

"But you see, it was condemned by religious and civic leaders, and it got bastardized. A famous dance team, Vern and Irene Castle, took out the hip contact, but that completely changed the meter of the music and turned it into what I call the bastard tango. The ultimate degradation was what you'd see Margaret Dumont and Groucho Marx doing in a movie.

"I think part of the reason the record has done so well is because the tango is analogous to rock 'n' roll. It's funky, it took the world by storm, it had something to do with sex, and there's an anarchist flavor to the lyrics. And in this day of Quaaludes, the tango isn't something that's cool. This is about sex that people kill each other over."

"If the only thing you think of as a tango is 'Hernando's Hideaway,' this record will make you pay attention," says Salzman. "By catching the bitter edge of the music, I think we've shown people something they didn't see before. The mood in the music is in many ways the same mood responsible for Peronism."

Sahl starts to recite a few lyrics from "Yira Yira," although all the songs on the album are instrumental versions:

When lady luck leaves you flat

When you're on the way to nowhere

When you've worn out your shoes looking for a buck to eat with

Then you'll see that everything is a lie and that love is nothing

Move on. . .

"Move on is yira yira," says Sahl, "which is exactly what the cops tell you when they want you to move along."

The recording of "Tango Project II," as it's being called, begins today, Salzman says. "This will be mostly material inspired by the Argentine style: Kurt Weill, Bill Schimmel's 'Tango for Toulouse-Lautrec,' our own tango from our opera, 'Noah', and Sigmund Romberg's 'Softly as in a Morning Sunrise.' "

"What fascinates me in this," says Sahl, "is that it's a seance, the same thing that happened with the rag album. You're communicating with the dead, and the dead come to life."