DIY Modular Synthesizer

[Len]

I have started building a Eurorack modular synthesizer from scratch. (If anyone knows why I'm doing this, please let me know.) I plan to design & build all of the modules myself, except for one.

I'm posting open-source design documents here: https://github.com/Len42/Synth
Please note that I'm a hobbyist, not a professional EE, and my designs reflect that!

Here's a pic of my progress so far:

[rpiloverbd]

Thanks for sharing with us.

[latchesheyhey]

  Gr8 work mate!

[Len]

Here's a new wavefolder module: https://github.com/Len42/Synth-pub/tree/main/modules/Wavefolder

[Len]

Here's a new envelope generator module: https://github.com/Len42/Synth-pub/tree/main/modules/Envelope2

[cncjerry]

You need a copy of electronotes.  I bought a copy a few years ago thinking I would do the same thing as you.  Came in a box the size of 5 reems of paper.  Lots in there.

https://sdiy.info/wiki/Electronotes

[Len]

Unfortunately he's no longer taking orders for hard copies of Electronotes. But a bunch of the articles are posted on the Electronotes site.

[Len]

Here's a VCO module using an SSI2131 chip: https://github.com/Len42/Synth/tree/main/modules/VCO-2131

[Terry Bites]

You are doing it because you fell through a wormhole into the 70's.
Schroff rack I hope!

[Len]

You are doing it becasue you fell through a wormhole into the 70's.
Schroff rack I hope!

I thought about getting an old server rack but I want it to be more desktop-friendly.

[cncjerry]

Unfortunately he's no longer taking orders for hard copies of Electronotes. But a bunch of the articles are posted on the Electronotes site.

I have a copy sent to me by Bernie (or maybe a helper) several years ago that I am thinking of selling.  The printouts came in a large paper box from paper reems.  Point was even though some are available as PDF, the cost of printing them yourself, as I calculated too, exceeded what they wanted to send them.  Contact me offline if someone wants to purchase them.  Same cost as I paid.

There are many tricks and techniques in the docs that have broad applicablity to audio.  Many related to keeping eveything in tune by preventing oscillator drift.

Jerry

p.s.: I was working on a general purpose module using the analog devices VisualDSP (might not be the name, but it is the block programming DSP software from AD).  I was planning to make a module that, with a PC loader, could emulate oscillators, ADSR, filters, amps, etc depending on the load from the PC module.   The modules had mutiple knobs and in/out connection that could be changed with the loader.  This was all digital, and that violated my analog principles so that was the first hangup... I got pretty far until I needed to implement control voltages for the keyboard. Then Roland released the boutique series of synths and I bought a few, then a deepmind 12, and now a Fantom88.  The issue with the Eurorack synths is that I found you quickly had a want/need for poly and that multiplies everything, of course.  And now the Fantom has n/zyme, that I found to just be incredible and can point to new movies, commercials etc that have that style of music..

[Len]

Here's an audio output module: https://github.com/Len42/Synth/tree/main/modules/Audiout

[Len]

Here's a quad VCA: https://github.com/Len42/Synth/tree/main/modules/VCA-4

[Len]

I made a simple Bus Driver module to patch CV & gate signals onto the Eurorack system bus.
https://github.com/Len42/Synth/tree/main/modules/Bus-Driver

[Len]

Here's a buffered multiple: https://github.com/Len42/Synth/tree/main/modules/Buff-Mult

[Len]

VCF work in progress

[Ground_Loop]

How are you doing design and fabrication of the faceplates. They look really nice.

[Len]

How are you doing design and fabrication of the faceplates. They look really nice.

Thanks! They don't look quite as good close up.

Some modules were made with a Delptronics Module Construction Set. This includes an alumin(i)um front panel with a drilling template printed on it.

Other modules use PCBs that I designed, so the front panel is a PCB with holes.

The graphics are just laser printed on adhesive-backed paper and covered with a clear adhesive lamination sheet.

[RoGeorge]

Noice! 
Were song?

[Len]

No song yet.

[Len]

Here's a dual mixer module: https://github.com/Len42/Synth/tree/main/modules/Mixer2

[Len]

sigh I bought a case. My system outgrew the hacky rack and power supply that I made and I don't have the tools or skills to make a proper case, so I bought one.

However I did engineer a sophisticated desktop cradle system to hold the case at a convenient angle.

(yes it's a cardboard box.)

[Len]

My synth finally has a filter! It's a 4-pole lowpass VCF based on an SSI2140 chip: https://github.com/Len42/Synth/tree/main/modules/VCF-4P

[Len]

Here's a dual attenuverter module: https://github.com/Len42/Synth/tree/main/modules/Attenuverter

[ajb]

Cool project! I know a bunch of people who are into synths as either musicians or equipment maker, it looks like a ton of fun to build and play those systems! Sadly for me (but happily for my wallet/free time) I have negative musical ability.

What are you using for your front panels?