But the unexpectedly intimate conversation came with repeated caveats – suggestions, he might call them – about how the interview should be presented so as to jibe with Stein’s public persona.

It was, of course, that flair for managing an image – for understanding, and controlling, how things look and sound – that made Stein one of the defining record men of our time, a Rock and Roll Hall of Fame inductee who established his reputation by consistently selling listeners on the next idea of cool.

The Ramones, Soft Cell, Everything But the Girl, Ice-T – in each of these diverse Sire acts, Stein knew what people wanted before they knew for themselves.

“Seymour goes with his gut,” says Clive Davis, a fellow music industry magnate who’s known (and competed with) Stein since the late 1960s. “And he’s always been right there, sniffing out who’ll be stars in the many years to come.”

Now, after decades of looking ahead, Stein is turning his careful gaze behind him. On Saturday, Sire will mark the label’s 50th anniversary with the release of a limited-edition box set featuring classic cuts by Madonna, Depeche Mode and the Smiths; Stein is scheduled to sign copies that afternoon at Amoeba Music in Hollywood as part of the shop’s festivities for Record Store Day.

Daughter Mandy Stein, a filmmaker who directed a 2009 movie about the New York punk club CBGB (where Stein first saw Talking Heads), is working on a documentary about her father. And Stein himself has almost completed a memoir due to be published next year.

“I’ve had a great life, and I’m still here – I’m still going,” he says, his arms folded across his barrel chest. “There have been a few strange incidents that happened. Nothing terrible.”

Born in Brooklyn, Stein entered the music business as a teenager when he convinced a couple of editors at Billboard to let him work on the magazine’s charts. He revelled in the data, in the way the numbers revealed patterns in popularity. But it wasn’t enough.

“I realised, ‘What am I doing here? Everything is happening outside!’ Rock and roll was being born,” he says, and Stein wanted in.

Jobs followed with independent labels including King (known for records by James Brown) and Red Bird (the Shangri-Las) before Stein founded Sire in 1967 with Richard Gottehrer, who’d found success a few years before as one of the writers and producers behind italics the Angels’ No 1 hit, My Boyfriend’s Back.

In its early days Sire licensed records by British and European rock acts for release in America; Hocus Pocus by the Dutch group Focus took off in 1973. Two years later, Stein caught a Ramones gig and signed the hugely influential punk band, who released their self-titled debut on Sire in 1976.

After that came a hot streak in which Stein seemed to predict where music was headed, from punk to new wave to synth-pop to metal. By the late ’80s, flush with cash from having sold Sire to Warner Bros., Stein was in a position to coax a comeback record out of the Beach Boys’ Wilson, who’d receded from music while under the questionable care of therapist Eugene Landy.

“It wasn’t easy, I’ll tell you,” Stein says of making the self-titled Brian Wilson, which came out to warm reviews in 1988. “I would have to say that (Landy) was the most evil person that I ever met.”

Asked why he went through with the project given the challenges, Stein scoffed. “This guy’s a genius,” he said, referring to Wilson.

Sure, but even geniuses run out of steam. “There are some people, less than a handful maybe, that are worth the effort, even if you’re going to lose,” Stein said. “And I didn’t think I was going to lose. But even if I had, I think it would’ve been what they say in Jewish - a mitzvah (good deed) – to have done this.”

Pulling off feats like Brian Wilson – and continuing to make new stars out of Seal and k.d. lang – transformed Stein into something of a celebrity himself, one capable of creating a stir every time he entered a crowded club.

Deven Ivy, the singer of a young Sire band called Residual Kid, said he thinks of Stein as Mr. Big from Wayne’s World – a cigar-chomping cartoon of an industry titan played in that 1992 movie by Michael Jackson’s former manager, the late Frank Dileo.

Stein admits he enjoyed being photographed with the famous artists on his roster, even if his constant work kept him from seeing his family. (Stein’s ex-wife was the Ramones’ co-manager, Linda Stein, who was murdered in 2007.)

Today, larger-than-life record men such as Stein and Davis have given way to lower-key executives better suited to the industry’s corporate structure.

“The thrilling years are gone,” Stein says. “There are people in the music business that are experts but not experts in music.” According to Davis, technology is now where the excitement is. Yet Stein appears to care little about the latest evolution in streaming.

“Seymour’s not that worried about how people are going to listen to the music,” says Warner Bros. Records chief Cameron Strang. “He’s lived through many, many different formats and changes in the way music is distributed.” What still drives Stein, says Strang, is the search for great artists and great songs.

Indeed, though Sire is a smaller concern than it used to be, Stein hasn’t stopped signing fresh talent. Last year the label put out Residual Kid’s grungy but tuneful Salsa EP, and in March it released Slowmotionary, the striking solo debut by Ethan Gruska of L.A.’s Belle Brigade.

And then there’s his book, in which he can tell his story the way he sees fit. Not that he hasn’t had to compromise his vision a little.

Stein’s original title for the memoir was “Shellac in His Veins,” after a phrase King Records’ Syd Nathan once used to describe Stein. (Before vinyl came into use, records were made of shellac.) But, Stein says, his publisher didn’t go for it. “We wound up calling it something I’ve come to terms with,” he said, without offering the new title. “These people, it’s a big firm.” He sighs. “I’m smart enough to defer sometimes. But I don’t think what we came up with is much better.

“But don’t print any of that. I don’t want to piss them off. They’ll throw everything in the garbage.”