The Arp 2600 Project.

Arp 2600
Arp 2600 Semi-modular Synthesizer. Mid 1970s model

The Arp 2600, Part 1

In what seems like a life time ago,  I worked as a circuit layout designer for a large aerospace company North of Toronto. This was back in the late 70s & early 80s, and that job provided a great education in electronic design, test and production methodology. This was also the dawn of CAD/CAM systems, Surface Mount Technology (SMT), flex circuits and the start of the embedded digital electronics for product engineering. I got to play with some very cool tools, and meet some interesting people. I specialized in the design of hybrid microcircuits and multi-layer PCBs. I also worked on everything from RF-4 Phantoms, CF18As, F14s, F15s, F16s, CF105s, C17s, Hurcs, Asraam, Amraam systems, Space shuttle, MD-11s, A320s, MD80s… somewhere in my dresser drawer, there is a tie clip for each aircraft, ship, tank and system I worked on. It was an awesome place to work and learn. There was a guy who worked over in the production engineering offices named Gary Benson.

Garrett Manufacturing, Toronto, Ontario

Gary and I were drinking coffee and having a break after a meeting, about interfacing the Zuken CAD system to the pick and place machines on the microcircuit line. We started talking about prog rock, Alan Parsons and what his favourite records were, etc. Of course, this led to a discussion about synthesizers and how he had worked in New York as a synth tech and repair person working on Arp and Roland equipment. He went on for quite a while, talking about the Jupiter 8 and how, it was the best synth made at the time and how he sold his Arp to use as a deposit on this beloved Roland. As a synth tech he said “Damn Arps, were fun to play with, but not very consistent in build quality.” He went on to say “Depending on which week of the month an Arp was made, determined the overall quality”. Gary knew a lot about production engineering and Arp and Roland synthesizers. Our initial discussion led to a working friendship, strange encounters at the El Mocambo Tavern, more discussions and put me onto an adventure in search of the Holy Grail of synthesizers.

Back in the late 70s and early 80s, small manufacturing companies (unlike Garrett Mfg) had a harder time making specialized products like synthesizers, in a playground of ever expanding competition. Big players like Yamaha could absorb some losses on underselling products, by spreading the losses over multiple product lines. They also had access to larger inventories of components or even custom made ICs (many were house brand offerings, but had the marking changed to obfuscate their function). Dollar for inflated Dollar, electronic components were far more expensive back then, then they are today. Imagine spending $6.00 on an OpAmp in 1971? That’s about $21 at today’s price, so you did not order a ton. Smaller companies kept minimal quantities of components on hand, basically covering a month’s worth of production. So, if you built 10 product X machines in June, you would order your parts for the 10 product X machines you would build in August, on June 30th. You may have kept some spares around (for repairs) but there was not many. If you ran out of resistors, capacitors, etc, of one value, you would use multiples to obtain the value you needed. You may even use a different type of capacitor or diode or other semiconductor. Delivery of components was a couple weeks away minimum and you could not wait to ship the product, because you relied on the income from the final sale to buy components and pay salaries, etc. For small companies, everything just took longer to order and receive, and if there was a large component shortage, the large companies would obtain the stock from the suppliers first. With that digression in mind, back to synths.

The 80s were not kind to the analog world of synthesizers.  Companies like Arp Instruments, EDP, EMS, Moog and Sequential did not survive financially for a variety of causes (and yet some have clawed back from the dead). But the underlying fact is they were (and still are) very expensive to make domestically and back in the day, these mono-analogs were not wanted as much as the new FM and digital polyphonic synthesizers. Yea, yea, yea…. I know, I know. As I write this there has been a resurgence of analog gear, and bringing old synth designs back from the dead is the trendy thing. But in 1983 and 1984…. nobody wanted analog synthesizers! Especially working musicians.

An Arp 2600 in the mid-70s sold for well over $2500. That’s equivalent to over $16,000 in 2020 bucks. Would you drop $16,000 on a mono synth today? Why did you end up here, on this page reading about a 50 year old synth? Maybe you want to know what all the hullabaloo is over when Behringer announced a remake of the Arp 2600 ($599)? Maybe you want to buy an Arp 2600 original for $13,000 or a Korg (Arp) 2600 reissue for $4500, or maybe you want to build your own TTSH for a couple grand. I had wanted an Arp 2600 ever since I first heard Tangerine Dream, and played with one at a sound show back in 1977. I had always dreamed of buying one, but could never afford one when they were made, and then with the digital revolution, marriage, kids, career, house payments…..

At this point, some additional context…

If you would like additional background info on the Arp 2600, please review the following links:

Here is a great demo video: Red Bull Academy

A advert for an Arp 2600: Tonus-ARP-2600-Blue-Marvin-Flyer

Great Synthesizers: The Arp 2600

Great Read: The Rise & Fall of Arp Instruments

Jon Dent has a great blog on Music Synthesis. He has a particularly good section on the Arp 2600 and clones.

Phil Cirocco is probably the most authoritative source for the Arp 2600, and provides repair and upgrade services (along with his own Arp inspired synthesizers) on his CMS page.

Alan R Pearlman Archives facebook group:

Video Article by Reverb: The Arp 2600

Back to this story on the Arp 2600…

I was at the El Mocambo Tavern one night to see the Edgar Winter group. It was a pretty good show, and after the first set the techs were on stage fixing an issue with some of the equipment the band was using. As I was sipping on my beer looking over a the stage, there was Gary Benson. Up on stage, working on some gear with the other techs. So, I head over and yell “hey Gary”. He smiles and answers back, and we start talking, he tells me he knows the band, the roadies, they sent him a ticket, how he was helping with this sequencer issue. He introduced me to the road manager (I can’t for the life of me remember the name) because at that moment… from behind me a voice says. “Did ‘yas’ get it fixed Gary”? It was Edgar Winter. At that point, I never doubted what Gary told me.

The El Macambo. Toronto, Ontario

I sat with Gary at his table for the second half of the show, and he told me he had met the band while he worked in New York for several clubs and venues. Basically, if bands had gigs in New York or “Jersey” as he put it, and equipment broke, and they needed spares, or repairs, he was on call. We talked about Blues, Funk and all sorts of music things, from recording techniques to the most rugged equipment for live performances… which led back to synthesizers. He said that Edgar Winter tried using the Arp for live performances early after recording ‘Frankenstein’, but that “Arp and Moog shit is best left in a studio, as they don’t travel well”. With all the newer, lighter digitally controlled synths at the time, you could understand his point, and besides, the analog synth world was dying and you could buy used Arps and Moogs for bargain basement prices. Broken ones could be had for scrap.

Gary invited me over to his house the following Saturday, and we ended up in his garage, which was filled with synth parts. I mean, he had parts for every Arp, Roland, Moog I knew of, and hundreds of parts for machines I never knew existed. Massive Leslie speakers, Amplifiers, Hammond organs, Racks of tubes! In the corner, was this stupid looking blue metal thing. I asked him if he made it himself and he replied “Ha! nope. that’s one of the first Arp 2600s made”. He told me he got it for parts, as it was “water logged” from a fire in a recording studio in Pennsylvania.  We pulled it out from under the pile, and opened it up to have a discussion on Arp’s production engineering. He told me that he had flown from New York to meet the Arp team, he met “Al and the guys” and took what he called, “service & tech training”. He then moved a few boxes of stuff off an old cabinet and pulled out these post type binders that were over 4 inches thick each, filled with tech notes, schematics and service charts.

It was not uncommon for small manufacturers to keep build sheets or service sheets to document differences between production units. Sometimes, they would put a carbon copy inside the equipment of a diagram or materials change notice, that would let a service tech know of any differences between the particular unit and the service manual. I can’t recall if Gary said Arp or Roland did or not, but he did have dozens of service sheets listing various repairs to Arp and Roland synths. He told me repairing an Arp was more about finding a “Dofor”. “Because when it was built or serviced” he said, “Some parts had to do for now”.

I told Gary I always wanted an Arp 2600, how I tried building my own Moog clone a few years prior and how I was going to build a modular synth of my own. He then said he always wanted to take an Arp 2600 and make a polyphonic, digitally controlled version. “Sound for sound” he said, “The Arp 2600s were the best”. I did not know, there were so many versions of an Arp 2600, Gary told me that the versions prior to the “Monkey Orange” (whatever that meant), had incredible sound. I really did not know there was a Blue metal or Grey metal version. After some discussion, he handed me a couple boxes containing Arp 2600 circuit boards, modules and parts. My mission was to develop a whole new set of PCBs that we could use as a test bed, in order to make a digitally controlled, polyphonic version. Of course, this would take place the next day or two later, and after consuming several beers and listening to his Jupiter 8 which was run through a Marshal stack at 1:00 am.

Over the next few days, I had gone through the boxes of circuits. I had enough boards to literally build two complete, (but non-functioning) Arp 2600s. Some of the modules were really early versions, they were not enclosed in potting compound and used varying or different components. Many of the boards had corrosion or staining, broken traces and broken hardware. At the company where we worked, we had a photography shop and a digitization table. I took the boards in one at a time, (to avoid suspicion of using company equipment on personal projects), and sent them over to get 1:1 photos of the boards. This camera would make 1:1 negatives of each circuit card that would be no more than 0.0005″ out over a 12″ run. Then I could take the negatives and get 4:1 enlargements made. Once that was done, I took the enlargements to the digitization table and could remake the PCB layouts for the CAD system. This was the same process we used for taking older aircraft circuit boards and loading them into CAD systems for renewal projects. It also worked well for reverse engineering of circuit boards from other places. It would take me 3 months, to get all of the main boards completed, and then I could start working on the smaller module PCBs.

The next 8 months saw much productivity. Gary and I met once a week over lunch, to review our project. We had imaged, digitized and produced 3 working sets of PCBs for the Arp 2600. Of course these PCBs were built to Mil-Spec (thats all we had access to). Being a stickler for production processes and details, Gary had developed the Bill of Materials and the assembly specs. He used his own versions of schematics, and service sheets from his files. He also provided the designs for additional testing equipment we would need for op amp and semiconductor selection. It was at those meeting I learned all about matching transistors and some of the critical elements in ensuring analog synthesizers were actually playable musically. Or, what many people thought was musical. Gary had also approached another software engineer, to assist in developing the new (modified) PCBs, for a digitally controlled version. The idea being, we would build 2 fully analog Arps, and compare them with the digitally controlled, poly versions we wanted to build. The intended design would use the 2 oscillators, the filter, and the VCA per voice, with a total of 6 voices. The whole thing was designed for a 9U VME bus where all voltage control would be digital. I was just completing the voltage control/processor board when all hell broke loose.

To Part 2 & the TTSH

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