In only a few years, the Harmonizer H910 had become standard equipment, ultimately being used on hundreds of releases including Tom Petty’s Damn The Torpedoes, Patti Smith’s “Because The Night,” U2’s early ’80s output and much of Van Halen and Ozzy Osbourne’s work of the same era. The history of the Harmonizer even made a tidy full circle when it was used on Walls And Bridges, the 1974 album by the machine’s namesake, John Lennon. The LP was recorded at the Record Plant, upstairs from the Eventide office.

“In those days,” Ciani says, “all of this technology was very personal. You knew the first names of everybody who designed everything: Don Buchla, Bob Moog, Richard Factor, Tony Agnello.” This familial atmosphere began slipping as technology evolved beyond artist circles and international corporations bought out the boutiques. Large and mostly Japanese corporations including Roland, Yamaha, Korg and Akai took over the scene by manufacturing and distributing on a scale that dwarfed the capabilities of the original designers. While these corporations grew the market considerably, they also changed the nature of the designs from analog to digital with new synthesizers like the Yamaha DX7, Roland D-50 and Korg M1. These low-cost, keyboard-oriented instruments became trendy among pop artists like Phil Collins, Kenny Loggins and Madonna, but didn’t find popularity among more experimental modular musicians. Moog Music declared bankruptcy in 1986; Yamaha took over San Francisco-based synth manufacturer Sequential Circuits in 1987 and Eventide stopped making modular units altogether in 1983. With this shift, artists who had based their output on these machines were left in flux.

“There was a lot of promise... but it didn’t manifest all the way to the end,” Ciani says. “They did create a market for the big public, but they never fulfilled the promise of a more discerning audience, which were the musicians themselves.”

More than 40 years after the release of the Harmonizer, the tides have once again turned as modern electronic artists have embraced classic modular instruments. Studio engineer Roy Hendrickson, a frequent Empire of the Sun collaborator, still has two Harmonizers in his studio. Although they require occasional tune-ups, he still uses them on every project for the unique spectrum of sounds they create. Aphex Twin used four Harmonizer H949s on Syro, which won the Grammy for Best Dance/Electronic Album in 2015.

“We’ve seen a revolution that reminds me very much of those early days,” says Ciani, who remains good friends with Agnello and Factor. “The kids came along and said, ‘We want to see what it was like back then. We want to feel the knobs. We want to feel the interfaces. We don’t want to just be working inside a computer with a mouse.’ They’re rediscovering, and I think it’s wonderful because the first time around, we didn’t quite finish.”

The Harmonizer’s continuing relevance is not just limited to this modular renaissance. Eventide, which now operates out of Little Ferry, New Jersey, released the plug-in version of the H910 in 2003. The program features all of the capabilities of the original machine, along with presets by producers including Hendrickson and Sasha. While the original machines remain trendy and beloved, the Harmonizer now largely lives inside of computers, having evolved along with the digital audio technology sparked decades ago with Factor’s DDL boxes. And although Eventide offers more than a dozen audio plug-ins, the bulk of their revenue now comes from devices that record years’ worth of data using digital compression and storage, and a machine that keeps profanity off television and radio.

43 years after its debut at the Waldorf Astoria, the H910 was inducted into the NAMM Foundation’s TECnology Hall of Fame. At the 2007 ceremony, Factor introduced Agnello, who accepted the award for masterminding a machine that shifted the history of recorded sound, and which some view as an extension of its creators’ own personalities.

“Now we have this technology that’s kind of a blank slate,” Hendrickson says. “Who knows how many other plug-in harmonizers are out there, but [these designers] don’t have the same minds as Tony Agnello and Richard Factor. They don’t hear the same way; they don’t build pitch-changing algorithms the same way. That’s why I think this thing sounds different.”