“Synthesizer Giveaway: Get Your Own for Free Today!”

One Tuesday a month, a small crowd packs into Tim Cox’s studio in the Brooklyn Navy Yard to commune with synthesizers. In one corner, a 20-something visitor plugs candy-colored cables into a complicated rig that pushes a wall of noise out of nearby speakers. Nearby, a middle-aged player in a Mets cap twirls and flicks the 100-plus knobs and switches of a 40-pound instrument called the GRP A4, which is the size of a large air-conditioner. First it sounds like a spaceship, then the ocean, then a thumping dance floor, before settling on a jagged beep with a satisfying crunch.

“People will play something and be like, ‘That’s the coolest thing I’ve ever heard in my life, and I can’t believe I made it,’” said Mr. Cox, a synth enthusiast who has seen many such “ear perk moments,” as he calls them, in his time hosting the gatherings. “If I shared this stuff with my friends, they’d say it sounds like a dishwasher. But it’s incredibly satisfying to create.”

Mr. Cox owns most of the synths at his jams. But the A4 is a loan from Synth Library NYC, a volunteer-run lending library that stewards a collection of 73 synthesizers available to any New Yorker who signs up. In exchange for unlimited use of the box, whose $6,000 price tag puts it out of reach for most players, the library requires Mr. Cox to host monthly visiting hours so that others can get their fingers on it.

“The immediate goal with the program is increasing access to gear, since buying it can be hard in such an expensive city,” said Heidi Sabers, a co-founder of the library who has D.J.’d and produced electronic music as Heidi Sabertooth for 10 years. “But the bigger one is creating a community around the magic of these instruments.”

Created in 2021 by Ms. Sabers and the multidisciplinary artist Cy X, the library now has 650 members and represents a cross-section of the world of synth fanatics in New York. Once a month, several dozen of them stop by a D.I.Y. warehouse space in Williamsburg to pick up their gear, which is provided by supporters or paid for by donations. Library members are on hand to help answer questions and share tips.

“I see it as mutual-aid resource sharing,” said Riley Wong, who organizes the library with Ms. Sabers. “There’s the physical equipment piece, and then the ‘what the hell is going on?’ piece. Having a friend be there with you for 20 minutes to show you what a knob means goes so far.”

Listeners have been captivated by these instruments since 1968, when the composer Wendy Carlos released “Switched-On Bach,” which used early analog synthesizers to mimic an orchestra, albeit a squelchy one. By the time Kate Bush’s synth anthem “Running Up That Hill” boomed across charts in 1985, tens of thousands of Americans had digital keyboards in their bedrooms and basements. Thousands more had drum machines and sequencers.

Demand never went away, but in the last decade, dozens of new boutique manufacturers have emerged, and larger companies are reissuing their vintage models. The focus is not on all-in-one keyboard workstations, but on wonky knob-and-switch boxes wired to mold an electrical signal into idiosyncratic sounds.

“It’s gone bananas, from being really far-out nerdy to being very popular,” said Peter Pearson, who has been playing synths since the mid-1990s. “A lot of it is dance music exploding in popularity,” he added, combined with alluring gear-porn videos from social media “synthfluencers.” This widespread interest allowed Mr. Pearson to open a synth repair shop seven years ago, his base for serving as Synth Library’s pro bono in-house technician.

Shelling out for finicky, expensive hardware might seem pointless when computer composition programs like Ableton can do nearly the same thing. But software instruments, synth acolytes insist, are lifeless simulacra of a tactile joy. “Flipping switches and turning knobs is this incredible physical feedback loop where you touch something, and then hear the difference that you’re making, instantly,” said Mx. Wong, who started playing synths just three years ago and has already moved on to building them. “I also love that you’re not hiding behind a screen when you work on these things,” they added.

A computer also can’t recreate the mystical quality that some find in the machines. Wes Marcarelli, a donor to Synth Library through his synthesizer company, STEM Modular, draws a tarot card before spinning up his rig, because “playing it feels like I’m communication with some other realm,” he said. For Mónica Torres, who joined the library this year having never before played synths, the instruments feel “synaptic, like it’s speaking to my nervous system, but also to the planets above us, the technology around us, things that are part of us and that we are part of.” The draw is so powerful that she treks from her home in Coney Island to the library’s Williamsburg storage space on checkout days.

With their infinite possibilities and multisensory offerings, synths seem to hold a particular appeal to neurodivergent people. Mr. Cox, who hosts the studio meet-ups, has A.D.H.D. “I’m very distracted by new things, and synthesizers present my ears with stuff they’ve never heard before, every single time I use them,” he said.

Lori Napoleon, a friend of Ms. Sabers who has advised her on the library, said that a recent A.D.H.D. diagnosis cast her 20-year career as a techno D.J. and producer in a clearer light. “I understand now that I’ve gravitated toward synths because they resonate with how my mind works,” she said. “They’re multimodal and haptic, and there’s feedback from both audio and lights, which is very engaging for my brain. And at the same time, you’re also sculpting and painting with an invisible, ethereal material” — electricity.

Like Mx. Wong, Ms. Napoleon builds her own instruments, often incorporating discarded electrical appliances like telegraph keys.

In the years since synths entered the consumer market, they have gotten smaller, and in most cases less expensive; one popular line of very capable pocket-size instruments retails for $99. Most enthusiasts suffer from a condition they call GAS — “gear acquisition syndrome,” the desire to expand one’s musical repertoire with an ever-growing hardware collection. Even the first purchase is daunting, especially on a limited budget.

When Cy X, the Synth Library co-founder, got interested in synths, they said, “My excitement and curiosity were so intense, and the weight of the financial burden was also so intense.”

Synth Library is not the first to address this disparity. Ms. Sabers and Cy X sought input from FeM Synth Lab, a similar project in Los Angeles that opened in 2020. Both were founded and are run by women and nonbinary people, but unlike FeM, the New York library decided not to restrict membership to any particular identity.

“There’s no rules for who can join, but it is focused on BIPOC and marginalized genders,” Mx. Wong said. “I notice in other scenes, there’s a lot of white guys with a lot of disposable income, whereas at Synth Library, there’s a focus on supporting people to go as deep into this world as they want to, regardless of their resource levels, and with attention to the barriers they might face in other parts of the synth community.”

Its latest project is a collaboration with Voluminous Arts, an incubator for trans artists founded by the composer and synth builder Gavilán Rayna Russom. In September, the library provided a long-term loan to the Voluminous Arts studio, which also includes some of Ms. Russom’s instruments.

“I see the malleability of electronic sound as connected to larger ideas about rethinking social structures and identity,” Ms. Russom said. “The idea that a sound can be fluid, change over time and change shape, is a parallel to my trans femininity.” Trans people have had a particular influence on synthesizers — Wendy Carlos, who introduced the sound to the masses with “Switched-On Bach,” was a trans woman.

Local collectors and manufacturers, Ms. Sabers said, rallied quickly around the library when she and Cy X began soliciting donations. One was Control, a shop dedicated to modulars, the original, esoteric, mad-scientist form of synthesizer. When Daren Ho and Jonas Asher opened the store in 2012, information about how to play synths abounded online, but it was “hard to digest because it can be so…