The finished Synthesizer

The making of the Saturn

DIY Doepfer board

This is what it all started with. It’s essentially a whole monosynth on one tiny PCB, and all that’s left to do is connect the connectors to the interface of a synth, and that’s what I set out to do in this project.

More specifications can be read on Doepfers website. It costs 100eur without temperature compensation, and 120eur with it. The synth actually has okay stability without it, but if it needs to work together with other synths, I’d recommend the temp-co version.

Anyway, first of all, I needed a design for the synth.

Look familiar? Hehe, it’s a recreation of the Korg MS-10 Layout I did as best as I could. There had to be some minor changes due to the internals of the Doepfer DIY, but overall it turned out pretty nice.

Next step was making it physical, so I printed out the layout (inverted to save ink) on label paper, and stuck it to an aluminium plate. After that I drilled the holes where the layout had them marked.

To keep it nice and tidy, I made small boards with the headers on them, with length-trimmed wires, so everything fit perfectly.

The first header finished. Overall it took around a week to get them all done, but mostly because I was busy with other stuff.

Here it is fully assembled, and fully functional as well. Some minor circuitry was made to make it function more like an MS-10. For example the square wave was clamped from -5v to 5v, to only 0v to 5v. This was done with a CMOS inverter. Other than that a noise circuit, and a 440Hz microcontroller reference sine was made.

The synth connected up to the plate. Not as nice as I wanted, but it was nice enough for a first synth.

The next step was to make a wooden enclosure for it. I tried to mirror the MS-10 once again, but as this was all wood and the MS-10 wasn’t, there was some changes.

The box fully assembled

It got 2 coats with oil called ‘swedish red’. It was the best oil I had laying around. This way the synth also matches the wooden frames for the windows around the house 😉

A test to see if everything fit, which it actually didn’t at first. The aluminium plate had to get ~1 millimeter shaven off lengthwise.

Up until now, the layout that has been on was just a drilling guide, so it’s time to put the real layout on.

Yes, this meant removing all electronics and everything from the plate. It took about 1 day, but the result was totally worth it.

Reassembled with the electronics, and fully functional.

How it would get powered was really important to me. I really wanted it to run straight off the mains, so it could be used anywhere, without an external transformer. I did this with a 240v to 15v transformer, and then about 10.000microfarads of filtering, and then 2 voltage regulators. One for +12v, and another for -12v.

It has rubber feet which were cannibalized off a fallen Casio.

Coupled with the keyboard it was designed to fit with. Their lengths are exactly the same.

It’s own little place in the music making setup 🙂

Overall, a project I’d recommend anyone wanting to go into synth building to do! It really gives you an idea of what there is to do, and in the end you have an awesome little monosynth that can also be used as a test bench for new stuff you make from scratch. For a demo of the sound, search for ‘Doepfer DIY’ on youtube, there’s tons of demonstrations of the sounds it can make.

The total time spent on the project was 1 month exactly, from the 1st of October till the 1st of November.

Total Cost

120€ – DIY Doepfer synth with temp-co

10€ – Wood

10€ – Aluminium plate

30€ – Potentiometers, knobs, cables, minijacks and misc. components

5€ – Mains transformer

175€ / 200$

~ Lysdal