Wish you were there? David Gilmour plugged in this EMS Synthi Hi-Fli to record tracks for Dark Side of the Moon and Pink Floyd: Live in Pompeii. It was photographed among Gilmour’s gear on display in 2017’s Pink Floyd: Their Mortal Remains exhibit at London’s Victoria and Albert Museum.

EMS Synthi Hi-Fli

In my experience, there is one unit that stands above the rest: the EMS Synthi Hi-Fli. This is the ultimate vintage guitar pedal, whether for its features, sound, looks, size, scarcity, price, or simply its star quality. I’ve been fortunate to own four or five over the years, with some overlap between different variations. At one point, I had a rare early prototype and one of the last MkII units. They all sound different, and each one has its own unique character. This is due to the varying degrees by which the 40-year-old components in these complex, discrete circuits have aged. I could have justified keeping them all on the basis that each had unique qualities I enjoyed. But my keeper unit is one of the last produced by EMS.

Built starting in 1972, the Hi-Fli was designed a year earlier by David Cockerell, who was also responsible for such legendary synths as the EMS VCS 3, Synthi AKS, and Synthi 100. In ’74, he moved to Electro-Harmonix, where he designed many classic pedals, including the Small Stone, Electric Mistress, 16 Second Digital Delay, and Microsynth. David Gilmour of Pink Floyd is the most renowned early adopter of the Hi-Fli. He began using a prototype onstage in 1972-’73 and in recording Dark Side of the Moon. A Hi-Fli is also visible in the film Pink Floyd: Live in Pompeii. He has two units to this day, though Floyd gear expert and Gilmour tech Phil Taylor maintains that he didn’t use the Hi-Fli extensively. The prototype was displayed at the stunning Pink Floyd: Their Mortal Remains exhibit at London’s Victoria and Albert Museum last year. Around 350 Hi-Flis were made, and other notable users include Steve Hackett of Genesis and Todd Rundgren.

Industrial designer Martin Holbrook’s iconic look for the Hi-Fli was a futuristic, curvaceous cream-colored fiberglass console, typical of late-’60s space-age design—although it was disparagingly referred to as “the toilet seat.” After the first 10 prototypes, which featured twin foot pedals built into the stand that supported it, the design was changed to a separate stand and pedals.

David Gilmour of Pink Floyd is the most renowned early adopter of the Hi-Fli. He began using a prototype onstage in 1972-’73 and in recording Dark Side of the Moon.

The prototype design, though undoubtedly far more aesthetically pleasing, was less successful ergonomically. Access to the pedals under the sizeable control section was difficult while playing guitar. After EMS ran out of cream fiberglass cases, the final 10 or so units produced were housed in garish orange-painted wooden boxes.

While the early prototypes miss some of the later units’ improvements, and some mid-period Hi-Flis didn’t have the “growl” modification, all examples I’ve played have been utterly captivating. I know of no other effects unit that is as sonically versatile or as compelling and expressive. The Hi-Fli oozes inspiration, but if you find a sound you like, be certain to hit record quickly, because it can be difficult to precisely recreate settings. There are many variable parameters, and the slightest movement of each of nine faders has a significant impact on the sound. So, the Hi-Fli has all the flaws, foibles, and idiosyncrasies you’d expect in an analog synth from the early ’70s. It is one of those rare magical devices that surprises and delights one moment, only to obfuscate and exasperate the next.

Set the Controls for the Heart of the Sun
The Hi-Fli is complex and nuanced. Of course, you can just plug in and move sliders and switches until you get a sound you like. But the Hi-Fli is divided into two main sections by the bypass mixer, which controls the wet/dry mix. On the left are the top boost, octave shift, and sustain fuzz controls, and on the right are the controls for the stunning and multi-featured phase filter section. This is where you select and shape the various phaser, vibrato, and filter settings: vibrato, phasing 1, phasing 2, waw, wawa, and meow—tags that provide a tantalizing glimpse of what’s possible.


Three faces of the EMS Synthi Hi-Fli (from left to right): one of the 10 original prototypes with pedals directly beneath the unit; a final production model after EMS had run out of fiberglass housings, with the “growl” switch in the phase filter section and a bypass switch in the midsection; and a mid-period example without the growl mod. The middle unit is the author’s and can be heard in the sound clips online.

Running along the bottom are the switches to control the left and right foot pedals. Being able to select positive or negative voltage for the various sliders (or leave them off) for each pedal puts a vast array of control options at your disposal. On the top left is the solo/strum switch, which determines the attack/decay time sensitivity. Later units also feature the growl, which uses a subharmonic to modulate the phase filter, yielding even wilder sounds.

If I filled this entire magazine, I’d still fall short of conveying the depth, scale, and sheer craziness of the sounds the Hi-Fli can create. One minute you’re in the amphitheater at Pompeii making seagull noises; the next you’re like an axe-slinging Kraftwerk mannequin. Yet it also excels at gentle and subtle phasing and vibrato. This is a design of staggering quality and ambition with possibilities that stretch far beyond anything else created for use with an unmodified electric guitar in the ’70s. Like a guitar, the Hi-Fli will sound very different depending on who is playing it. Over the years, I’ve created all manner of scrumptious electronic noises using different Hi-Flis, and I still don’t feel I’ve come close to exhausting the sonic possibilities of this wondrous device. But in the neighborhood of $5,000 and up today, Hi-Flis are an investment in more than a learning curve.