Restoring an Original '67 Moog Modular Synthesizer

For nearly half a century, a piece of synthesizer history sat in storage at Roosevelt University in Chicago along Michigan Avenue. Circuits decaying, connections dirty and corroded, long-ago attempts at repair abandoned.

And then Mike Borish came along.

The real-estate-broker-turned-electronics-technician found out about the forgotten gem from a client who worked at the university.

After confirming with a professor exactly what it was that the client had seen - Unit 1029, one of only several dozen modular synthesizers built in the 1960s by R.A. Moog, synth pioneer Bob Moog’s first company - he knew what he had to do.

Borish had to open it up, get his hands in there, and bring it back to life.

There is no monotony in this machine."

Life may seem like an odd choice of wording to those who see synthesizers as cold, algorithmic imitations of mechanical instruments that require breath, blood and sweat. But, as Borish says, there is no monotony in this machine.

Components were painstakingly matched and tested by human hands. Filter bands used coils wrapped by real people, imperfectly, giving the whole system an organic feel.

“You get a different thing every time it runs through the sequence,” Borish says.

Were the imbalances and asymmetry he discovered the result of mistakes? Damage? Or just idiosyncrasies that were there from the start?

In trying to answer that question with care and reverence, Borish restored Unit 1029 with an incredibly high level of fidelity to the original. The result is a fully functional time capsule that reminds us just how timeless the Moog sound is.

Early R.A. Moog Modular Synthesizers

It’s not all that unusual that this original Moog modular system lived at a university.

When they were made in the 1960s, the groundbreaking machines took up an entire room and cost the equivalent of a small house in today’s money.

The few that were produced were purchased by well-funded university music programs, deep-pocketed studios like Motown (which owned Unit 1028) and ambitious artists like The Byrds and Mick Jagger.

Bob Moog started building large modular synthesizer systems in the mid-1960s after founding R.A. Moog in the 1950s to build theremins. The technology was largely experimental and still in development through the end of the decade.

It wasn’t until Wendy Carlos cemented the synthesizer’s place in wider world of music that the technology’s full potential was realized. Carlos, who studied physics and music at Brown before fully dedicating herself to music composition at Columbia in 1962, won three Grammys for her breakthrough album Switched-On Bach (1968) and later composed the synthesizer scores for A Clockwork Orange (1971), The Shining (1980), and Tron (1982).

Unit 1029 at Roosevelt University was built in the fall of 1967, right at the flashpoint of initial synthesizer experimentation. One of the first commercial synth albums, The Zodiac: Cosmic Sounds, had just been released, but the tipping point was still a year away.

It is a subtractive synthesizer, with two banks of four oscillators. There are three main interfaces: two keyboards and a ribbon controller. It also has a control panel where the keyboards and ribbon controller can have the control voltages routed by switches.

How is it different from the circuitry you might find, say, in a modern Moog Mother-32? The biggest difference might be the built-in uncertainty. As Borish explains:

“These early 901A [modules] have low compensation, mid high compensation, and high compensation as well a a general scaling potentiometer for calibration purposes. If you play all of the keys, this outputs some wicked volt/octave ratios.

The tuning on the oscillators is equally complicated. The 901B oscillators are matched to the 901A by trial and error. It is possible for an oscillator to be in tune for an octave, drift for the next, and then be in perfect tune for the duration of the scaling. It makes for some interesting tuning scenarios.”

This particular unit also contained an early version of Moog’s 904 transistor ladder filter. Its four-step filter process represents one of the key innovations in electronic music.

The inductor-based filters are handmade, with different coils for different filter bands, something you’re not likely to see these days. It was precisely this hand-matching of components that made the restoration so tricky.


Restoring Moog Modular Unit 1029

Mike goes into each restoration with the aim to “alter the synth as little as possible with respect to the original intentions of the designer.”

He will say that this job was mostly cleaning, replacing some finite parts and then calibrating it, but the reality was much more complicated.

He first contacted Dan Wyman, author of the Moog Modular Owner’s Manual, who suggested that he listen to to the Nonesuch Guide to Electronic Music for an idea of how this system is supposed to sound.

After uploading pictures and asking around, he found two other systems from exactly the same time period, one of which that used to be owned by Mickey Dolenz of The Monkees. Examining photos of similar systems helped Borish put the pieces together.

Replacing electrolytic capacitors that are subject to serious degradation and frequent failure from aging were the first things to come out. Then he cleaned the switches and potentiometers. Power supplies were replaced with modern equivalents.

According to Borish, the hardest part was deciding what needed replacing or recalibrating in the first place:

Are all of these wild irregularities a feature or a bug? Who knows, but they sure are fun to listen to."

“Drifting components gave me lots of stuff to think about, components that have changed their electrical values and are no longer in tolerance. It wasn't that they were hard to locate or fix. It was that a change in their values resulted in different sonic qualities. In other words, I had a lot of trouble determining if some bugs were actually a feature and if I should tinker with them.

I can easily argue that a ‘broken-in’ Moog system is similar to an unmolested Blackface Super Reverb. Everyone knows that a vintage amp sounds different after you replace the speakers, tubes, caps, etc. I've met several musicians that would rather not fix their gear unless smoke comes out of it because they don't want to lose the sound.

But, is an early Moog supposed to drift out of tune occasionally? Sure. Are idiosyncrasies found in different modules important or should I make them all totally uniform? These were just some of the important questions I had to address.”

Many early Moogs get their characteristic sound as the result of interdependent precision components that may have slight differences from module to module. Borish continues:

“The 901 modules are a great example of this. Each oscillator footing requires a hand matched bundle of components to create a certain pitch at a specific control voltage. Changing these around is a big can of worms that can alter your scaling, shape of your output waveforms, and amplitude. Also, Unlike the 921 oscillators which are based on operational amplifiers and are far more disciplined, the 901B's are relaxation oscillators, based on unijunction transistors, and are subject to their own special kind of pitch drift and scaling issues. 901's are tuned differently too. Are all of these wild irregularities a feature or a bug? Who knows, but they sure are fun to listen to.”

Other difficulties?

“Some of the modules don't have DC-blocking capacitors and are subject to drift and offset. Impedance matching among components is awkward with some configurations. The system wasn't set up for computer interfacing either, so I made some modifications to accommodate modern studio technology.”

Above any argument about what should or should not have been modified or replaced during the restoration, you can hear oscillators and filters producing a sound all their own, pleading with us to stop the debate and just listen to the music.

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