DIY Modular Synthesizer - Page 1
Forum section: electronics / projects

author: Len
author_rank: Frequent Contributor
timestamp: December 10, 2021, 08:11:02 pm
content: I have started building a Eurorack modular synthesizer from scratch. (If anyone knowswhyI'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/SynthPlease note that I'm a hobbyist, not a professional EE, and my designs reflect that!Here's a pic of my progress so far:

author: rpiloverbd
author_rank: Regular Contributor
timestamp: December 11, 2021, 11:03:32 am
content: Thanks for sharing with us.

author: latchesheyhey
author_rank: Newbie
timestamp: December 15, 2021, 03:08:21 am
content: Gr8 work mate!

author: Len
author_rank: Frequent Contributor
timestamp: January 21, 2022, 01:54:04 am
content: Here's a new wavefolder module:https://github.com/Len42/Synth-pub/tree/main/modules/Wavefolder

author: Len
author_rank: Frequent Contributor
timestamp: January 31, 2022, 12:46:03 am
content: Here's a new envelope generator module:https://github.com/Len42/Synth-pub/tree/main/modules/Envelope2

author: cncjerry
author_rank: Unknown
timestamp: January 31, 2022, 04:31:13 pm
content: 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

author: Len
author_rank: Frequent Contributor
timestamp: January 31, 2022, 04:49:47 pm
content: Unfortunately he's no longer taking orders for hard copies of Electronotes. But a bunch of the articles are posted on the Electronotes site.

author: Len
author_rank: Frequent Contributor
timestamp: March 10, 2022, 03:42:54 pm
content: Here's a VCO module using an SSI2131 chip:https://github.com/Len42/Synth/tree/main/modules/VCO-2131

author: Terry Bites
author_rank: Super Contributor
timestamp: March 10, 2022, 04:06:16 pm
content: You are doing it because you fell through a wormhole into the 70's.Schroff rack I hope!

author: Len
author_rank: Frequent Contributor
timestamp: March 10, 2022, 04:47:28 pm
content: Quote from: Terry Bites on March 10, 2022, 04:06:16 pmI thought about getting an old server rack but I want it to be more desktop-friendly.

author: cncjerry
author_rank: Unknown
timestamp: March 12, 2022, 08:17:28 pm
content: Quote from: Len on January 31, 2022, 04:49:47 pmI 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.Jerryp.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..

author: Len
author_rank: Frequent Contributor
timestamp: April 01, 2022, 07:57:15 pm
content: Here's an audio output module:https://github.com/Len42/Synth/tree/main/modules/Audiout

author: Len
author_rank: Frequent Contributor
timestamp: April 06, 2022, 03:43:22 pm
content: Here's a quad VCA:https://github.com/Len42/Synth/tree/main/modules/VCA-4

author: Len
author_rank: Frequent Contributor
timestamp: June 19, 2022, 07:02:31 pm
content: 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

author: Len
author_rank: Frequent Contributor
timestamp: June 30, 2022, 04:51:12 pm
content: Here's a buffered multiple:https://github.com/Len42/Synth/tree/main/modules/Buff-Mult

author: Len
author_rank: Frequent Contributor
timestamp: July 15, 2022, 09:56:38 pm
content: VCF work in progress

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: July 19, 2022, 04:05:00 am
content: How are you doing design and fabrication of the faceplates. They look really nice.

author: Len
author_rank: Frequent Contributor
timestamp: July 19, 2022, 02:42:15 pm
content: Quote from: Ground_Loop on July 19, 2022, 04:05:00 amThanks! They don't look quite as good close up.Some modules were made with aDelptronics 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.

author: Len
author_rank: Frequent Contributor
timestamp: July 19, 2022, 03:09:37 pm
content: No song yet.

author: Len
author_rank: Frequent Contributor
timestamp: August 03, 2022, 07:24:44 pm
content: Here's a dual mixer module:https://github.com/Len42/Synth/tree/main/modules/Mixer2

author: Len
author_rank: Frequent Contributor
timestamp: August 15, 2022, 04:53:12 pm
content: sighI 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.)

author: Len
author_rank: Frequent Contributor
timestamp: August 16, 2022, 02:02:44 pm
content: 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

author: Len
author_rank: Frequent Contributor
timestamp: September 24, 2022, 04:09:55 pm
content: Here's a dual attenuverter module:https://github.com/Len42/Synth/tree/main/modules/Attenuverter

author: ajb
author_rank: Super Contributor
timestamp: September 24, 2022, 06:28:02 pm
content: 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?

author: Len
author_rank: Frequent Contributor
timestamp: September 24, 2022, 07:54:53 pm
content: Quote from: ajb on September 24, 2022, 06:28:02 pmMy musical ability isn't great but I plan to work on it whenever I finish making modules.QuoteYou're the second person to ask this, so I put the answeron a web page.

author: Len
author_rank: Frequent Contributor
timestamp: September 24, 2022, 08:22:31 pm
content: Here's a prototype for a digital voice module that I've been working on for a while. It still has a long way to go.

author: Len
author_rank: Frequent Contributor
timestamp: November 03, 2022, 06:30:57 pm
content: Here's a digital effects module:https://github.com/Len42/Synth/tree/main/modules/FX

author: Len
author_rank: Frequent Contributor
timestamp: November 13, 2022, 06:49:06 pm
content: Here's a unity-gain mixer / precision adder module:https://github.com/Len42/Synth/tree/main/modules/Adder

author: Len
author_rank: Frequent Contributor
timestamp: December 26, 2022, 09:14:06 pm
content: Here's another small mixer module:https://github.com/Len42/Synth/tree/main/modules/Mixer1

author: Len
author_rank: Frequent Contributor
timestamp: January 12, 2023, 01:59:17 am
content: Here's another filter module, different from the first one:https://github.com/Len42/Synth/tree/main/modules/VCF-SV

author: Len
author_rank: Frequent Contributor
timestamp: July 23, 2023, 08:04:47 pm
content: This one has been a long time in the making. It's a digital FM voice module based on an RP2040 microcontroller board. Writing the firmware was a lot of work, and I also had to write patch-editing software.Github:https://github.com/Len42/Dexy

author: Len
author_rank: Frequent Contributor
timestamp: July 27, 2023, 01:08:25 am
content: Now that I have finished the final module* here's the state of my homebrew Eurorack system after about 2 years of work.* There is no such thing as a final module.

author: Len
author_rank: Frequent Contributor
timestamp: November 02, 2023, 01:08:30 am
content: Here's the module after the final module- it's a 4-channel muting module:https://github.com/Len42/Synth/tree/main/modules/Switches

author: cncjerry
author_rank: Unknown
timestamp: November 02, 2023, 06:52:56 pm
content: We need some sound!

author: Len
author_rank: Frequent Contributor
timestamp: November 03, 2023, 12:23:14 am
content: Quote from: cncjerry on November 02, 2023, 06:52:56 pmOne of these days, when I've figured out how to record stuff with a DAW.

author: Len
author_rank: Frequent Contributor
timestamp: January 31, 2024, 01:38:12 am
content: This is the FINAL final module for my homebrew Eurorack system (following the previous final module, which was after the first final module). It's a dual filter - not voltage-controlled, fingers only. 👌https://github.com/Len42/Synth/tree/main/modules/Filter2

author: Len
author_rank: Frequent Contributor
timestamp: May 28, 2024, 04:06:10 pm
content: You thought it was finished? HA! I only had one LFO, and I needed more LFO, so I made a dual analog LFO in a 4HP module.https://github.com/Len42/Synth/tree/main/modules/LFO-Analog

author: Len
author_rank: Frequent Contributor
timestamp: October 23, 2024, 05:09:41 pm
content: OK, this reallymustbe the last module I make because I have run out of space in my case! It's a multi-function module so it really should be the last one that I need.

author: Len
author_rank: Frequent Contributor
timestamp: November 27, 2024, 11:06:07 pm
content: The multi-function module is done! That is, the hardware is finished and I've written several programs for it (VCO, drums, delay, reverb, quantize).Details:https://lenp.net/synth/dat-ting/