EMS Synthi Hi-Fli Prototype (HiFli)

A very rare prototype Synthi Hi-Fli, dating from 1972, in excellent condition following a full overhaul by EMS earlier this year. One of only ten pre-production units made.

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A very rare prototype Synthi Hi-Fli, dating from 1972, in excellent condition following a full overhaul by EMS earlier this year.

One of only ten pre-production units made in 1972. David Gilmour reputedly still owns two of them…


[ Price reduced at the request of the seller.]

Ultra-rare prototype EMS Synthi Hi-Fli – this is a knob-twiddler’s dream of an effect and the ultimate in hens’ teeth: your guitar will never sound the same again.

Different sound and spec to a standard Hi-Fli – this is the second such unit we’ve had and it broke my heart to sell the last one (I’ve been a committed HiFli nut since I bought my first one many years ago and have always had at least one in the studio ever since).

The prototypes don’t have the growl function, which was introduced about 18 months later. Production Hi-Flis all have the Buzz switch, but only the first ten prototypes had the Fuzz switch, which adds some interesting colouration to the up and down-octave sounds.

Ten production prototype Hi-Flis were made in 1972 but a redesign quickly followed the launch at the Frankfurt Fair to try to reduce the factory cost (the prototype design is not especially ergonomic for a guitar player to use – you have to lean back somewhat to access the pedals underneath the main unit). This original design features a removable aluminium pole which plugs into the underside of the main console and the top of the base unit, acting both as a stand and a conduit for power and signal connections (pole not included with this unit). The heavy-duty nylon-dipped base houses the power supply and sturdy twin pedals.

Dave Gilmour of Pink Floyd is reputed to still have two of these original units, which, according to Phil Taylor were first used for the Dark Side of The Moon tour that started in May 1973 at Earls Court. Opinion is divided as to whether a Hi-Fli featured on the DSOTM recordings: I can only say that it certainly sounds like it did.

Number one in Analogman Tom’s list of rare guitar effects from his excellent book.

Used by David Gilmour – see this Gilmourish blog for further details – he bought a prototype in 1972 and from what he recalls it was “very, very expensive”; Gilmourish also suggest it was used during the recording of Dark Side Of The Moon

The physical design of the control panel differs from later Hi-Flis. The font used for the legending is different, as are the four rotary control knobs and caps for the sliders.

The specification of the Mk1 Hi-Fli prototype is slightly different to the main production run which followed. Whereas the Phase Filter section with six effects (vibrato, phasing 1, phasing 2, waa, waw and meow) and six control waveforms is the same, the Octave Shift section on the left is different. Instead of Octave Shift and Ring Mod mix sliders it has Up/Down and Level. With the Up/Down slider set halfway the octave shift has no effect and a clean signal results. Moving this fader down from the mid-point introduces progressively more down-shifted signal. Moving the fader up introduces ‘up-shifted’ signal. The level fader to the right controls the overall level of the signal passing through the Octave Shift section. Note there is an extra switch here labelled ‘Fuzz’. This provides a different (more subtle) colouration to the up/downshifted signal than that provided by the ‘Buzz’ switch. The Top Boost and Sustain Fuzz sections perform as normal. Note that the pedal assignment switches are on/off rather than plus-off-minus.

The Hi-Fli is supplied with a separate 8-way female-female connector cable which can be used in situations where the aluminium pole (missing) is not required. The AC mains connection is via a detachable mini-Bulgin lead (as used on EMS Synthis).

The Hi-Fli was designed by David Cockerell in 1971 for EMS. Only 350 were originally made making it a very rare beast indeed.

The Hi-Fli was actually referred to as a synthesizer in the original ad, but it’s basically an analog multi-effect processor, which can be used on vocals, guitars and organs. It has two footpedals, which could be routed as control voltages/expression pedal to any of the slider functions. It’s got no memory to bank up settings, – everything is in real-time, so one had to manually tweak the sliders for each tone change. You’ll suddenly hit upon an amazing combination while tweaking the knobs – be sure to hit record as repeating it can prove elusive.

Se the item photos for a shot of David in his home studio in 1972 with a prototype of the 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 by Robin Wood 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.

“AnalogMan’s Guide to Vintage Effects” by Tom Hughes

and the David Gilmour Gear Forum.

Excerpts from the Gilmourish post written by HiFli owner “Richard”.


In excellent cosmetic condition with only minor scratches on the face. The case is very good with some dings and signs of wear. See photos for more information on cosmetic condition.

Voltage Information

220/240v unit. A step-up transformer will be required for use on 110/120v supplies. Please ask if you need advice on what to use. We do not recommend using cheap, generic Chinese mains transformers.


For sales in UK/EU, this item is on the margin scheme for second hand goods. VAT-free sales are not possible for this item.


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