The synthesizer might not be the sound of the future any more, but it's one of the few instruments invented within living memory. Highly-anticipated independent documentary I Dream of Wires explores the history, demise and resurgence of the modular synthesiser, easily identifiable by the layman as that imposing-looking vertical wall of knobs and wires resembling a telephone exchange and lacking a keyboard.

If you're accustomed to seeing BBC Radiophonic Workshop era footage of these huge instruments being played by labcoats in bow ties, the latest chapter in their story is a different one entirely, with a recent resurgence coming about thanks to affordable hardware by manufacturers such as Doepfer, Modcan and Synthesizers.com and an active community of users.

Affordability is part of the story, but a more fundamental reason behind the return of the modular synth is a broader desire in the music making community for an alternative to mass-market synths such as the MicroKORG, released in 2002, that come loaded with preset sounds all too conveniently arranged by genre and apeing sounds from well-known territory. A symptom of the ongoing X-Factorisation of music making, for many, playing these instruments can be a pretty joyless exercise that feels part of some fame-chasing gameplan – in short, like a job. Similarly, most music production software features softsynths modelled on 'classic' hardware that can sound impressive, but turn music making into yet another activity done while staring at a screen. Simply put: modulars, with their bespoke nature, physicality and endless variables, have made synths exciting again.

Kicking off its four-hour running time with a detailed account of the emergence of the synthesiser, I Dream of Wires includes interview footage with many lesser-known characters of this story, well beyond the well-worn Robert Moog, Walter/Wendy Carlos and Leon Theremin territory. Contributions from Don Buchla, Ramon Sender and Morton Subotnick (who recorded Silver Apples of the Moon) reveal the motivations and desires for something completely new among those behind early incarnations of the intrument. As Morton Subotnik states: 'If it had a keyboard, I was going to produce regular music, and that's not what I wanted to do.'

The collective excitement at the infinite possibilities offered by this new sonic pallette is reinforced by erudite contributor Daniel Miller, founder of Mute Records. When Walter (now Wendy) Carlos recorded the album Switched On Bach using an early Moog, it sold millions, but left some, including Miller, bemused. Presented with a chance to expand the vocabulary of music, Switched On Bach narrowed it right down again. Aware of the sonic possibilities offered by the synth, Miller recalls thinking at the time, 'Why would you want to do that with it?'

Picking out key models such as Moog Modular, Minimoog and Korg 700S, I Dream of Wires closes its historical overview when digital tools the Fairlight sampler and mass produced Yamaha DX7 emerge around 1983. The sound of analog wouldn't really be heard on many records until Acid House began misusing the Roland TB303.

Picking up the story in the present day, the affordability of parts and an active online community has led to the emergence of many enthusiast manufacturers, often working from their own homes, who make their own interchangeable modules for users to mix and match in their synth setups. This sounds like the story coming pleasingly full circle, the crucial difference being that modern synths don't suffer from the tuning problems that dog their vintage counterparts.

The tuning might be reliable, but they remain unpredictable. As Factory Floor's Dominic Butler states, his fear of reliably getting his modular synth to make the same sound twice is exactly what gives their live shows an edge. As another key contributor, John Foxx, states, 'Accidents are plentiful and are often satisfying.' The fleeting and transient nature of the sounds is key to the instrument's appeal.

In fact, lingering close-up shots of analog synths aside (and there are a lot of these), perhaps what's most joyous about I Dream of Wires is that it profiles a subculture that has almost nothing to do with the music industry. Many of the synth users featured don't even bother recording the music they make. For many, it's an activity in itself – something to get lost in, not to make music with. Like a garden or a model railway, a modular synthesizer is never finished.

With contributions from Trent Reznor, Gary Numan, Vince Clarke, Chris Carter, Carl Craig, Flood, James Holden and Deadmau5, this crowdfunded documentary by a small team of filmmakers (one of whom, Jason Amm also recorded the score) is a major achievement, even if the straight-talking English voiceover artist they employed is occasionally at odds with an informal script. For some, the four-hour running time might seem as indulgent as some of the music played on the late 70s monster incarnations of these instruments, but for those with more than a passing interest in synths, or in the mechanics of how music evolves, four hours might not be enough.

I Dream of Wires is available in DVD and Blu-Ray via: idreamofwires.org

"I Dream of Wires: Hardcore Edition" trailer (09/2013 re-issue)