Recording engineer, producer and mixer Al Schmitt has worked on more than 150 platinum and gold records, won 20 competitive Grammys, and satisfied some of the most exacting artists in the business, from Quincy Jones to Ray Charles, Steely Dan, Tony Bennett, Barbra Streisand and Miles Davis. Yet the very start of his career came from a scheduling mishap that few apprentice studio rats would have survived with nerves intact.

“The first session I ever did was for Mercer Records, with the Duke Ellington Orchestra,” he remembers. “It was an accident, it wasn’t even supposed to be on the schedule, but I was the only one in the studio. I was so intimidated; I was not prepared for that.

“Duke Ellington sat next to me, he looked into my eyes, and he just knew I was ready to die. And so he patted my knee, smiled at me, and said, ‘Don’t worry son, we’re gonna get through this.’”

With that as an introduction, Schmitt hasn’t been intimidated by much since. Though he’s stayed safely behind the scenes for the entirety of his six-decade career, one look at his discography makes it clear why he’s set to receive a star on Aug. 13 on the Walk of Fame, in front of the Capitol Records building.

After the initial trial-by-Ellington, he settled into a position as RCA’s first house engineer, at times recording sessions with Sam Cooke, Ike and Tina Turner and Henry Mancini all in the course of a single day. He ventured out into producing in the mid-’60s, crafting records for Jefferson Airplane, Neil Young and Al Jarreau, then rededicated himself to engineering in the mid-’70s. His most significant collaborators since then have been Diana Krall (with whom he’s won three Grammys), Paul McCartney, Luis Miguel, Celine Dion, Madonna and Natalie Cole.

In 2014, the 85-year-old stepped into the studio with Bob Dylan for the first time, engineering last January’s “Shadows in the Night.” It’s safe to assume the session went well, as Dylan has already secured Schmitt’s services for his next LP.

“It was a totally different session for him,” Schmitt remembers of Dylan. “He sang softer, and we got this great sound on his voice, really rich and warm. After he heard the first playback, he was so excited, it made everything else go so much easier.”

Going into the session, however, Dylan made a request that surprised even the veteran: Not only did he want to record the entire album live, but, in an attempt to inculcate a loose living-room vibe in the studio, he didn’t want to see any microphones other than his vocal mic, forcing Schmitt to draw on all his invention to hide recording devices all throughout the room.

“But I love doing that kind of thing,” he says. “Because we get our stuff together real quick, and they’re happy with the way everything sounds. And so much of the time the first take is the (best) take anyway.”

Adapting to the times has been a necessity throughout Schmitt’s career, and he identifies ProTools as the most significant innovation of his many decades in the business. Though he says he now uses the software for all his sessions — “except for Bob and Neil,” he corrects — it took him a while to come around to digital recording.

An analog man at heart, Schmitt couldn’t ignore the leaps in recording technology forever, and would A-B sessions — recording simultaneously on his computer and on reel-to-reel tape — until finally even he couldn’t tell the difference between the two.

Yet Schmitt shares Young’s distaste for the audio quality of much streaming music and mp3 formats. “Some of that streaming stuff is just dreadful,” he says, “it’s absolutely terrible, I don’t know how people can listen to it.” Asked if he’s taken to mixing with an eye toward digital formats, Schmitt draws the line.

“I know guys that do that, but I don’t. I make the best sounding recordings I can, with the best quality mixes I can do. And that’s it. What they do to that afterwards, I have no control over that.”

Recording methods aside, Schmitt’s style has remained the same over the years: Unadorned, unpretentious and eternally attuned to the possibility of magic erupting on the other side of the glass.

“You can always tell” when the take is a keeper, he says. “When I did ‘Unforgettable’ with Natalie, you knew immediately it was going to be a big hit. Everyone who heard it, their jaw dropped. And all the things I did with Sam (Cooke), ‘Cupid,’ ‘Bring It on Home,’ they just had that magic. You’d get goosebumps, the hairs would stand up when he was doing it. And those are all live recordings, so that makes a big difference, when you’re hearing everything the way it’s gonna be.”

Born in Brooklyn, Schmitt’s auditory instincts were honed by essentially growing up in a recording studio, working for his uncle Harry Smith at Brunswick Records starting at age 7. He was later adopted by mentor Tom Dowd, who employed him at New Apex studios and Nola, then moved to Los Angeles to work at Radio Recorders. When heavyweight songwriter Mancini clashed with his engineer, Schmitt stepped in to fill the void, working on the Grammy-winning “Theme From ‘Hatari’” and “Moon River,” from “Breakfast at Tiffany’s.” He quickly landed a job at RCA, where the hits started coming at a frantic pace.

He recalls with fondness the rough-and-tumble early days, when enterprising producers might lay a gun down on the mixing board at the start of a session, and spending more than 45 minutes on a song was a sign of needless extravagance.

“I miss that period a lot,” he says. “The great thing was you would do two or three sessions a day, and you would do all kinds of music; classical to country to rock and roll to R&B to Henry Mancini.

“Plus, you had to capture it all in the moment,” he continues. “You had to really be on your toes and know what you were doing, but it was a lot more fun then. More than, you know, overdubbing guitars for hours and overdubbing synths for hours. I mean, it’s the way records are made today, and you do your job and get it done. But it isn’t quite as much fun.”

On that note, Schmitt seems to relish novel challenges, whether its Dylan’s microphobia or his last album with Young, “Storytone,” which Schmitt recorded live, sans overdubs, alongside a 65-piece orchestra and a 35-voice choir. Young’s producer Niko Bolas convinced Schmitt to take on the project by admitting, “Al, I don’t know anyone else who can do this anymore.”

But despite his reputation — in addition to having won at least one Grammy in each of the past six decades, Schmitt received an honorary doctorate from the Berklee College of Music last year — the soundman still doesn’t think he’s quite attained the gold standard of his craft.

“As far as I’m concerned, I don’t think there is such a thing as a perfect sounding record,” he says. “I’ve made records that won Grammys and everything, but I’ll hear those records two years later on the radio, and I’ll always say, ‘Boy I coulda done that better.’ Or ‘Why did I let that happen?’ So I’ve never made a record I was 100% happy with. And I don’t know if too many people could say they have.”