How Sound Selection works in the Yamaha CS-80

Yamaha CS-80 angled closeup of front

One of the things that has been the most helpful for me over the years in sort of syncing up my general understanding of electronics theory with understanding how synthesizers are actually designed is reading circuit descriptions in service manuals. A lot of the American companies especially wrote really great, detailed explanations of how their instruments worked, and reading them has helped me to both understand the specific circuits they discussed, and understand more broadly how different objectives in synth design can be achieved… and more quickly recognize what’s going on in an unfamiliar circuit.

Because I’m a nerd I guess, I thought it might be fun to make some step-by-step “circuit descriptions” like that for synth circuits that don’t have them.   My first featured circuit –the system through which the Yamaha CS-80 handles preset, panel and memory switching– is sprawling, but actually fairly simple, much like the synth that it comes from. Continue reading “How Sound Selection works in the Yamaha CS-80”

The MemoryMoog (Plus): American Monster Polysynth

The development and release of the Moog MemoryMoog (and MemoryMoog Plus) was the last gasp of the Moog company in the 80s. Around 1980, the two younger American synth companies, Sequential Circuits and Oberheim, were thriving, putting out one new synth after another. By the time the Memorymoog came out, SCI and Oberheim had already released multiple true polysynths. The Japanese companies were cranking out one new polysynth after another. The two remaining from the old guard of major American synth companies, ARP and Moog, were acutely aware of the serious market pressure to put out polysynths of their own. Each had already barfed out a big, cumbersome, paraphonic psuedo-poly (the ARP Quadra and the Polymoog, respectively) but it was REALLY time for them to get their act together, hire some programmers and design a true polysynth with digital voice assignment and control.

Continue reading “The MemoryMoog (Plus): American Monster Polysynth”

“Don’t be that guy”

Roland CSQ-600: in which the tech replaced the NiCad memory battery but installed the replacement battery in a ziploc bag ziptied to the mains wiring.

One interesting thing about restoring vintage synths is that almost every instrument that we work on has been worked on by another tech at least once before. And it seems that more often than not, those other techs were… not great. We see a lot of bad work, but my favorite examples also feature a very special element of absurdity. Here are some recent highlights:

Continue reading ““Don’t be that guy””

Desoldering Tutorial: Tools, Techniques and Helpful Tips

the frikkin desoldering gauntlet

I would say that desoldering is much harder than soldering. It took me a couple weeks to get good at soldering and several years to get good at desoldering, partly because I didn’t used to do it as often when I first got into electronics, just building circuits from kit PCBs and schematics. Working on old synths though, I have to desolder all kinds of things constantly from different kinds of boards and have refined my techniques pretty well, so I thought I’d share some of what I’ve learned here. Continue reading “Desoldering Tutorial: Tools, Techniques and Helpful Tips”

Roland Jupiter 6 – calibration tips

Roland Jupiter 6
Roland Jupiter 6

The Jupiter 6 is one of Roland’s two most beloved 80’s polysynths, the other being the Jupiter 8. While I was looking for service documents for the Jupiter 6 though, I came across some absurdly aggressive forum posts from people who don’t like this synth and are pointlessly mad that a lot of other people like it a lot. Continue reading “Roland Jupiter 6 – calibration tips”

a DCO is not a digital oscillator

VCO vs. DCO vs. Digital Oscillator

I keep hearing and seeing people referring to DCOs as digital oscillators, which is not correct, and a sad insult to DCOs in my opinion as a lover of DCO synths. So I decided to fight misinformation by making a post here explaining the actual difference between VCOs, DCOs and digital oscillators. Continue reading “a DCO is not a digital oscillator”