Kent Spong – vintage synthesiser repair

Former Glories featuring Kent Spong

Kent Spong: analogue repair man – Sound on Sound June 2013

Somewhere in suburban Surrey is an unremarkable semi-detached house much like any other. But despite appearances this dwelling doubles as a Tardis-like warehouse through which regularly pass examples of some of the world’s finest synthesisers. Musicians and synth collectors bring their ailing vintage equipment here, like pilgrims to the Lourdes of the synthesiser world, to the healing hands of Kent Spong – Synthesiser Repair Man. Sound On Sound talks to Kent about analogue’s enduring appeal, exploding Moogs, and the importance of knobs.

The enduring popularity of analogue synthesisers means that many vintage instruments have lived on decades after their designers imagined they’d be only so much scrap metal and plastic. The same keyboards circulate between musicians, studios and collectors, and the recognisable sounds of favourites like the Yamaha CS-80 or Minimoog continue to appear on newly released records – often in genres undreamt of when they first appeared, and decades after their designers imagined they’d be only so much scrap metal and plastic. Some were manufactured in such limited numbers – from the low hundreds to low thousands – that the small and ever-decreasing supply assailed by an insatiable demand has pushed prices beyond even the king’s ransom they sold for originally.

Kent Spong of Kent Spong Restorations (KSR) provides the repair and restoration prowess for RL Music, founded by his old school friend, synth dealer Richard Lawson. He estimates Yamaha manufactured only 800 to 850 CS-80s – the 100kg synth perhaps most associated with Vangelis’ albums and epic film soundtracks from the late 1970s and 1980s (China, Chariots of Fire, Blade Runner) – of which around 300 have come through his workshop. They were expensive in 1977, when they sold for £5,000 (the average UK house price was about £10,000); last month a fine example sold on eBay for £11,700.

“I have seen CS-80s that at one time would have been broken for spares, but now they’re restored, almost at any cost, because people are willing to spend the money to bring them back,” Kent says. “I would imagine there’s still about 700 in circulation – mostly in studios being used as workhorses, but when restored they behave themselves and can be used for touring.”

Keeping this select class of equipment functioning more than 35 years later gets harder as spares become more scarce. “The customised ICs in the CS-80 are not exactly abundant,” says Kent. “I used to be able to cannibalise a wrecked CS-50 or even a really destroyed CS-80 and break it down for spares. But you can’t do that any more because the machines’ value has risen by so much that even for a wrecked CS-80 people will want three or four thousand pounds – for something that doesn’t work.”

Today, there’s a full family of Yamaha CS-80, CS-70, CS-60 and CS-50 awaiting Kent’s ministrations, alongside an Elka Synthex, ARP Odyssey, MiniMoog, Juno 60, Prophet 5, Prophet 10, and a huge Oberheim eight voice – and that’s just in the front room. There’s no photo that can do justice to just how full of keyboards this house is (“It’s actually not that bad at the minute,” says Kent). It’s enough to make any gear-head go weak at the knees and cross themselves as if in the presence of holy relics.

“There is a degree of worship involved with people’s relationship to this stuff,” Kent laughs. “The people from After The Fire came round with a CS-80 they’d had from new, but had dragged around for years. It was in a pretty terrible state. We completely restored it, rebuilt the whole case – it took five weeks,” he recalls. “When he came over to try it out, he walked into the workshop, clapped eyes on it and burst into tears. Playing it, hearing it, he was just beside himself.

“Musical instruments can be a part of the musician. The way the instrument sounds and how it plays become part of the process of creation, even if it’s not right. I mean, people have brought in keyboards saying they’re perfectly in tune, but when I check they’re miles out. They’ve just got used to it being like that, and incorporated it into what they do.”

Such reverence or excitement is not always brought about by the equipment’s musical abilities, but for the potential to turn a profit – as is clear from the difference between £4000 for a broken CS-80 that costs £11,700 when restored, implying that even a few thousand pounds spent on restoration is money well spent.

“It’s interesting to note that these were flagship machines,” says Kent. “Flagship machines tend not to sell well. The CS-80, the Synclavier, the Fairlight – these were expensive in their day, they didn’t sell many so they stopped making them, and they’re worth a great deal now because there’s so few of them around.”

Compare this to the Yamaha DX1, the company’s flagship digital synthesiser of which only 140 were made, introduced in 1984 for £9,000 and now selling for £6,000. Or the cut-down but equally competent and hugely popular DX7, which can be snagged for as little as £200. There’s money in analogue gear like no other.

Restoration station

Softly-spoken, bespectacled and capped with fly-away grey hair that gives him the air of a retired wizard, Kent’s interest in synthesisers was always musical rather than technical. Now 50, he’d always played pianos and organs as a child, and hearing Vangelis perform Chung Kuo (a favourite he’s covered) on breakfast television in the 1980s cemented his love for synthesis. “The sound just smacked me in the face. I fell in love,” he recalls. “I learnt how to use synths like everyone else back then, by spending hours in my room fiddling with knobs. It wasn’t until later when I started getting problems with keyboards that I started looking at the technical side of things.”

Kent did some occasional session work for a small label, Scabrie Reocords, and wrote music with Richard Lawson. “He was my partner in crime. I’d buy my keyboards and he’d buy his, and we’d put them together and make like Tangerine Dream,” he chuckles. “Every now and then we’d put together a demo and see if a record company was interested. They never were.”
Taking the time to repair a broken key on his Korg Mono/Poly circa 1982, he found friends were impressed by his willingness to open up the synth and get his hands dirty.

“Despite the electronics theory and skills I’d learnt, when it comes to repairing synthesisers there is no book you can buy – they operate outside logic in some respects,” he jokes. “You can understand how a capacitor and a transistor do what they do, but when it comes to locating faults on a machine that has aged well beyond what the designer ever imagined, you get very weird things going on.”

By the mid-1980s he had added synth repair to the computers repair he was offering at the time, starting with simple problems such as scratchy potentiomers and faders or broken keys.

Kent recalls: “Then you just rang up the company and ordered a part, but now a huge amount of what I do is scour the planet for obselete components. Paradoxically, now I can find a filter board for a Minimoog much more easily than I can find a computer board for a Korg M1. The M1 is about 20 years old while the Moog is nearly 40 years old, but the longevity of the M1 was never considered to be more than a few years before being superceeded so they made fewer spares, perhaps expecting lower failure rates. It’s much harder to find components for mid-90s equipment. The Roland JD-800, for example: if the keyboard membrane goes you’ll struggle to find a replacement.

“A lot of it comes down to trying to reach a price point – to reduce costs manufacturers would use components that were becoming obselete even at the time, so there’s no hope of finding them today. There are transistors in the ARP 2600 that are almost impossible to find, and are so specific that today’s drop-in replacements don’t work.”

With the silicon wafers of chips of the time fabbed on a six micron process compared to today’s wafers measured in nanometers, there is little chance of remanufacturing them ICs today – even if the dies, long since lost, could be found or reverse-engineered.

Undeterred, electronics sages have tackled that very problem. Jeroen Allaert from Ghent in Belgium spent years to painstakingly reverse engineer the original Juno 106 VCF/VCA controller PCB to produce a perfect clone that solves the manufacturing defects of the original. What does Roland think about this? They stock his parts.

“We generally find a lot of machines tend to fail in the same areas,” Kent says. “When someone phones me up to say one key of every six on their Juno 106 doesn’t work, I’ll tell them the VCF/VCA has probably gone on the voice, order the part ahead of time, and when the Juno arrives I’ll open it up and lo, that’s the IC that’s blown.

“It’s one of the most common faults alongside power supply problems. Some synths have PSU’s barely capable of running them, while others are overrated. The PSU in a CS-80 could power a whole village without trouble.”

Kent’s less common problems include an exploding Moog Modular which fired a lightbulb across the workshop, a faulty Synclavier disk drive that on inspection contained a huge dead spider, a ‘broken’ Korg PS3200 that actually just had no voice cards (from eBay, natch), a working Korg MonoPoly that inexplicably contained a man’s leather shoe, and a CS-80 inside which was nestled not only a rather nice gold man’s watch but a very old cheese sandwich.

While Allaert’s efforts are impressive, the circuit and chips (Roland’s IR3109) involved are (comparatively) simple. Once complex, customised and undocumented chips start failing, the game is surely over.

In Philip K Dicks’s seminal novel Do Androids Dream of Electric Sheep? (which became the film Blade Runner), Deckard desperately wants to buy a sheep for the status symbol of having a real animal rather than a synthetic equivalent. It’s only a matter of time before the surviving vintage analogue equipment becomes the ultra-rare, ultra-expensive ‘real’ animals in a field of ‘digital’ androids. But does it really matter?

Kent ponders. “Serious musicians want and relish the difference that analogue can provide. Nothing quite sounds like a CS-80. Nothing can really copy the sound of opening a filter sweep on a Mininoog. So yes, it does still matter.”

Kent Spong’s analogue Top 5

Yamaha CS-80 – “My personal favourite. It just sounds so, so rich. It’s so big – literally and metaphorically.”

Minimoog – “I love the Minimoog. Even apart from the sound, it has such great design: perfectly minimalist and compact, a case with an angled front laid out beautifully. It’s the Chanel Little Black Dress of the synth world. Wonderful.”

Moog modulars – “I love the old Moog kit too, the sounds of the 60s. Again, they look so amazing. They’re a nightmare to use though, you can spend ages with patch cables trying to get a noise out of it – but when you do its presence is incredible.”

Sequential Circuits Pro 1 – “This was a monosynth version of the Prophet 5. In it’s little case there’s a keyboard, stepping sequencer, arpeggiators, repeater, and modulation routing coming out of its ears. A fantastic machine.”

ARP 2600 – “This has really grown on me in the last few years. As an instrument it can be very tiresome to work on which has perhaps always tainted my opinion, but I really do like it, even more than the Steiner-Parker Synthacon. Another very expensive machine though.”


Black box with knobs on

“But owning them is part of it too – owning a Stradivarius violin is not the same as owning a Stradivarius DSP plugin,” he adds.

Software synths like Reaktor, Reason, the venerable Rebirth and any number of sample sets have brought musicians life-like sounds for reasonble prices. In fact, without the leaps and bounds digital sampling technology and computing power have made over the last few decades we’d be stuck with the same ‘string synth’ sounds instead of the sound of actual strings.

“You can download or buy a disc of the most incredible orchestra samples, but there’s nothing to touch,” Kent says. “For the drop of a hat and a few hundred quid – the price of a single session violinist – you have a complete orchestra in the studio. Digital comes into its own and allows you things that would never be otherwise possible.”

The appeal of that potential caused many to dump their gear and buy into the digital revolution. “I remember hearing the Kate Bush single with the broken glass sample [Babooshka] – the concept that someone was producing that by pressing a key was like magic. The keyboard player might as well have had a top hat, a cape and a waxed moustache. A lot of people were taken by that,” Kent recalls.

“I sold my whole collection – a PolySix, Mono/Poly, Prodigy, Roland MC-202 sequencer and CR-78 drum machine – to a dealer for £275 to put down the deposit for an Ensoniq Mirage. In hindsight, 20 years later you have that ‘doh’ moment when you realise the Mirage is worth fifty quid and the Prodigy alone is getting on for a grand.”

The irony is that the obsession with analogue keyboards’ sounds and their (usually pale) imitations of instruments means modern keyboards offer them too. “Recent keyboards always include presets that point to other keyboards – Moog bass, ARP this or MS-20 that, as after 30 years people liked that sound,” says Kent. “That it sounded nothing like what it tried to emulate in the first place isn’t important – now the aim is to recreate the original flawed imitation’s sound in all its imperfections.”

Perhaps these images of the cardboard box that contains an orchestra, or the powerful digital keyboard administered through a tiny screen illustrate how another appeal of analogue instruments is their physical, tacticle controls: the importance of having knobs on, as Oscar Wilde might have said.

“A lot of professional musicians want the interaction of pushing the buttons and twiddling the knobs. It’s part of the process, part of the creative aspect of making music,” Kent enthuses. “Changing the sound in real-time, having tactile controls available to you is going to change your mindset – you’re going to think differently if the interface is a black up/down button on a black front panel on a poorly lit stage. If you have immediate controls in front of you, you can explore that different feeling of playing live rather than in the studio, the excitement, the interaction with the audience.”

A look at the market reveals a huge range of punch buttons, scratch pads, joysticks and other physical MIDI inferface controllers, Korg’s Kaos Pad range, and Yamaha’s Tenori-On synth-sequencer-controller. Korg even released an imitation MS-20 USB MIDI controller complete with keyboard, knobs and patch bay to provide an authentic means to manipulate its Legacy Collection sample set of classic Korg sounds from the MS-20, Polysix, Wavestation and M1. That was almost 10 years ago; now they’ve released the new but 100 per cent analogue Korg MS20 Mini, and the other big names are on the case too – the revitalised Moog Music company’s Moog Voyager and Little Phatty, former Sequential Circuits designer Dave Smith’s Prophet ’08 and ’12 and Evolver, Tom Oberheim’s new SEM modules and Son of Four Voice synth, and Arturia’s MiniBrute.

And so analogue returns to the mainstream, adding new DNA to the genepool. As Kent points out, there’s more people building analogue gear now than ever before, each a nod to the sounds and tactile control of the past with the programmability and flexibility of the present. It’s also a sign of how far technology in how well today’s digital and analogue circuitry work side by side.

“Take the Voyager,” Kent says. “It doesn’t sound exactly like a Minimoog, but that doesn’t matter. The interesting thing is that they’ve managed to capture that Moog sound and then computer control it, giving you facilities that an original Moog could never give you.

“That’s good. That’s progress.”


Keeping ’em running

Vintage synthesisers now entering their fifth or sixth decade in use are inevitably going to hit problems, but they needn’t be show-stoppers with these tips.

Battery leaks – any keyboard with patch memory will have a battery which, over decades, runs the risk of leaking corrossive acid and causing potentially serious damage. Korg Polysix, later Polys, SH-101 and Rhodes Chromas are just some of those susceptible. NiCad and alkaline batteries are more likely to leak and should be replaced with lithium batteries if possible – it’s worth checking if you never have.

Capacitor leaks – capacitor electrolyte is not likely to cause damage directly, but dead capacitors aren’t regulating current as they’re supposed to. This exposes delicate components to power spikes, and alters the voltage and therefore the effects of oscillators and filters. Check for bulging or blown caps, and listen for rattling or clicking sounds which are frequently signs of power supply capacitor failures.

Scratchy pots and sliders – with gravity working as it does, dust is bound to work its way into the workings of sliders and knobs, causing a build up of debris and static that becomes an audible irritant. A dust cover is a simple way to reduce it, and a smoke-free environment helps too.

Dead keys – keys stop responding when the carbon contact underneath wears off so that the circuit is not completed. Graphite spray or replacement carbon contact ‘pills’ will solve the problem – but this will require require going under the hood.

Stuck keys – another common keyboard problem caused by the rubber bushings which push depressed keys back up into place become brittle and crumble, leaving keys stuck down. They can be bought online cheaply, but you have to get the right type for the keyboard – and again, it means opening the synth.

Misfiring CMOS chips – the comparitively primitive CMOS ICs from 20 or 30 years ago don’t last forever, and logic and timing errors caused by failing chips are difficult to diagnose. At least some chips (like the 4000 series) are replacable using modern equivalents, although there may be hundreds of them in a synth.

Keep it cool – a synth that lives in direct sunlight is more likely to overheat and develop dry solder joints than one that is kept cool and in the shade. It will fade the case too, especially those wood-effect panels.

Use it – get used to turning it off when not in use, as this will extend the lifespan of some components. But equally don’t let a vintage synth lie around unused – fire it up periodically, let it warm up, and give it a work out to ensure capacitors don’t dry up. Buy a proper flight case for storing it long term, throw in some packets of silica gel and store it flat.


[Originally published in Sound on Sound magazine, June 2013]

One Comment

  1. I’m obsessed since watching the documentary on the BBC… I’ve realised Vince Clark is one of my favourite songwriters ever. xxx

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