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Restoring Analogue Synthesizers

Kent Spong
Published June 2013
By Michael Parker

Kent Spong: vintage instrument restorer.

Vintage synths are objects of fascination to musicians and collectors alike. But keeping them alive takes a special kind of expertise...

The enduring popularity of analogue synthesizers means that many vintage instruments have lived on decades after their designers imagined they'd be only so much scrap metal and plastic. Keyboards circulate between musicians, studios and collectors, and the recognisable sounds of favourites like the Yamaha CS80 or Minimoog continue to appear on newly released records, often in genres undreamt of when they first appeared. Some were manufactured in such limited numbers — from the low hundreds to low thousands — that the small and ever-decreasing supply and insatiable demand have pushed prices beyond even the king's ransom they sold for originally.

Kent Spong of Kent Spong Restorations (KSR) is one of the UK's few experts in the maintenance and repair of vintage analogue synths, and as well as offering his services directly to owners, he restores instruments for RL Music, founded by his old school friend, synth dealer Richard Lawson. It's a specialised business. Kent estimates that Yamaha manufactured only 800 to 850 examples of the CS80, the 100kg synth perhaps most associated with Vangelis's albums and film soundtracks for Chariots Of Fire and Blade Runner. Of these, around 300 have come through his workshop. They were expensive in 1977, when they sold for £5000 (the average UK house price was about £10,000); recently, a fine example sold on eBay for £11,700.

"I have seen CS80s 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 such synths functioning more than 35 years after they were made gets harder as spares become more scarce. "The customised ICs [integrated circuits] in the CS80 are not exactly abundant,” says Kent. "I used to be able to cannibalise a wrecked CS50, or even a really destroyed CS80, 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 CS80, people will want three or four thousand pounds — for something that doesn't work.”

Restoration Stations

An example of how complex analogue polysynth design can be: the interior of an Elka Synthex.An example of how complex analogue polysynth design can be: the interior of an Elka Synthex.

When I visit, there's a full family of Yamaha's CS-series polysynths — CS80, CS70, CS60 and CS50 — awaiting Kent's ministrations, alongside an Elka Synthex, ARP Odyssey, Minimoog, Roland Juno 60, Sequential Circuits 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, even though Kent insists that "It's actually not that bad at the minute.” It's enough to make a synth fan weak at the knees.

"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 CS80 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. 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 CS80 that costs £11,700 when restored, implying that even a few thousand pounds invested in 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 CS80, the Synclavier, the Fairlight: these were all 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.”

Tangerine Dreams

Synth restoration doesn't only involve fixing the electronics. Like this Oberheim Eight-Voice, many old instruments stand in dire need of cosmetic improvement!Synth restoration doesn't only involve fixing the electronics. Like this Oberheim Eight-Voice, many old instruments stand in dire need of cosmetic improvement!

Softly spoken, bespectacled and capped with flyaway grey hair that gives him the air of a retired wizard, Kent's interest in synthesizers was originally 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: http://t.co/6qvTqXwW) 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 Records, 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 that 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 synthesizers there is no book you can buy. They operate outside logic in some respects. 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.”

Some of the instruments that pass through Kent Spong's workshop are extremely rare, like this PPG 1003 Sonic Carrier.Some of the instruments that pass through Kent Spong's workshop are extremely rare, like this PPG 1003 Sonic Carrier.By the mid-1980s, Kent had added synth repair to the computer repairs 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 obsolete 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 superseded, so they made fewer spares, perhaps expecting lower failure rates. It's much harder to find components for mid-'90s equipment. The Roland JD800, for example: if the keyboard membrane goes, you'll struggle to find a replacement.

"A lot of it was trying to reach a price point. To reduce costs, manufacturers would use components that were becoming obsolete 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 fabricated with a six-micron process, compared to today's wafers measured in nanometers, there is little chance of remanufacturing the 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 (www.analoguerenaissance.com/D80017/) spent years painstakingly reverse-engineering the original Juno 106 VCF/VCA controller PCB to produce a perfect clone that solves the manufacturing defects of the original. What do Roland think about this? They stock his parts.A perennial problem for synth restorers is finding components, especially obscure integrated circuits.A perennial problem for synth restorers is finding components, especially obscure integrated circuits.

"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 PSUs barely capable of running them, while others are overrated. The PSU in a CS80 could power a whole village without trouble.”

Kent's less common problems include an exploding Moog Modular that fired a light-bulb 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 Mono/Poly that inexplicably contained a man's leather shoe, and a CS80 inside which was nestled not only a rather nice gold man's watch but a very old cheese sandwich.

Digital Meets Analogue

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. But with digital modelling synths offering more features for less, does it really matter? Kent ponders. "Serious musicians want and relish the difference that analogue can provide. Nothing quite sounds like a CS80. Nothing can really copy the sound of opening a filter sweep on a Mininoog. So yes, it does still matter. But owning them is part of it too — owning a Stradivarius violin is not the same as owning a Stradivarius DSP plug-in. You can download or buy a disc of the most incredible orchestra samples, but there's nothing to touch. At the drop of a hat, and for 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.”

Kent freely admits that he himself fell prey to the allure of sampling when it first became popular. "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. I sold my whole collection — a [Korg] Polysix, Mono/Poly, [Moog] Prodigy, Roland MC202 sequencer and CR78 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 50 quid and the Prodigy alone is getting on for a grand.”

Tiresome to work on, but a great instrument: the ARP 2600.Tiresome to work on, but a great instrument: the ARP 2600.

The irony, of course, is that one of the functions of analogue synths was supposedly to emulate 'real' instruments; now those emulations are themselves being emulated. "Recent keyboards always include presets that point to other keyboards — Moog bass, ARP this or MS20 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.”

Another part of the enduring appeal of analogue instruments lies in their physical, controls. "A lot of professional musicians want the interaction of pushing buttons and twiddling knobs. It's part of the process, 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 mind set — you 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.”

Modern synth designers have long since learned this lesson, and there are now many digital instruments with 'knobby' control surfaces, not to mention novel controllers such as X-Y pads and Roland's D-Beam. But even that hasn't stemmed the demand for true analogue synths, which are undergoing something of a renaissance. Korg's new MS20 Mini joins big names such as 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. As Kent points out, there are 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 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 Them Running

Vintage synthesizers now entering their fifth or sixth decade in use are inevitably going to hit problems. Here are Kent Spong's top tips for keeping them going.

  • Beware of battery leaks: any keyboard with patch memory will have a battery which, over decades, runs the risk of leaking corrosive acid and causing potentially serious damage. The Korg Polysix and later Poly models, Roland SH101 (designed to run from batteries) and Rhodes Chroma 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.
  • Check your capacitors: 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.
  • Prevent scratchy pots and sliders: with gravity working as it does, dust is bound to find 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.
  • 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 going 'under the hood'.
  • Stuck keys are another common keyboard problem, caused by the rubber bushings that push depressed keys back up into place becoming brittle and crumbling, 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.
  • The comparatively primitive CMOS integrated circuits 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 replaceable 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. Sunlight will fade the case, too, especially those wood-effect panels.
  • Use it! Get used to turning synths 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 that capacitors don't dry up. Buy a proper flightcase for storing it long-term, throw in some packets of silica gel and store it flat.

Kent Spong's Analogue Top Five

  • Yamaha CS80: "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 one, but when you do, its presence is incredible.”
  • Sequential Circuits Pro One: "This was a monosynth version of the Prophet 5. In its 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.”
Published June 2013