Synth DIY FAQ

This page, like most pages on my website, is a work in progress. If you have questions you’d like answered here, comment below, or write a question on your own website and send me a webmention!

Philosophy

Why did you build a modular synthesizer?

At first I was just curious to see if I could build an analog oscillator. Once I made that, I wondered if I could build a filter. I made a filter and some more circuits and began to realize this was something that was within my reach.

Why DIY instead of just buying a commercial synth?

Cost. There is no way I’d ever be able to afford a monster commercial modular system. Have you seen those prices!? I’ve seen module prices anywhere from $50 to $900. Ever since I learned about modular synths I wanted to have one, but the cost of entry was prohibitive for me. Music is not my main source of income; I can’t rationalize spending thousands of dollars on a hobby like this! Plus, I like to DIY stuff, learn things, and experiment.

Eventually will you upgrade and get a “real” system?

Probably not. I absolutely love my synth, and I love that it doesn’t sound or look like any other synthesizer. It has its own quirks, its own issues, its own particular sound. I have built it to be incredibly specific for my own needs and creative impulses; the impetus for creating new modules is “It sure would be great to have a ____” or “Gee, I wonder what it would be like to have a ____ in my system.” It’s true that all modular systems are unique and catered to the whims of their owners, but I’d say mine is especially unique and unusual.

I’ve only had the opportunity to play with commercial modular synthesizers twice ever: both at the fantastic (but unfortunately-named) Knob Con synth convention. As it turns out, I was well into building my own modular before I’d ever touched a commercial modular. I love them, but I love my own instrument more. Sure, there are some commercial modules I’d love to have in my system, but I also love the challenge of trying to replicate their functionality on my much more limited synthesizer.

If you’d never played a “real” modular, how did you know you wanted one/how to make one?

I have always gravitated toward modular audio environments when making music on the computer. I have spent a considerable amount of time playing with Plogue Bidule, Max/MSP, Audulous (iOS), Pure Data, virtual versions of Moog modulars, and a number of other modular-style computer patching environments. I love the freedom to try new combinations, to decide signal-flow, to experiment, to create novel sounds. I love the idea of building a sound from scratch, starting with virtual oscillators, plugging them into virtual filters and virtual VCAs. Since almost every virtual modular synthesizer emulator is based on hardware, it’s not difficult to make the transition to the real world; although things may sound a bit different, they basically work the same way.

Construction

How’d you build the cases?

I found free pallets on Craigslist, transported them home in my truck, cut them up, and assembled more-or-less 19″-wide (standard rack-width) cases. I make the rails myself: I buy these thin metal strips at the hardware store – I think they are for drywall stuff– and then I drill holes every 1/2″. I stained the wood with gel stain. At some point I’ll find my original hand-drawn plans for the cases and post them here.

Why bolts instead of regular audio connectors?

At first my plan was to use regular 3.5mm audio connectors, the same size used on iPhones. They were too expensive for the number of jacks I knew I’d eventually need, so I thought about using banana jacks instead. Even those were a bit too pricey for me! When I saw Phobos’s brilliant Lunetta modular on the electro-music.com forums, I was sold. There are a number of benefits to using bolts as jacks and alligator clips as connectors:

  • Extremely cheap. Each bolt costs around $0.09, and alligator clips can be bought or made very, very cheaply. Plus, I already had a bunch of them, and it makes it extremely easy to test out new circuits: just connect the breadboard directly to the synth
  • Easy to wire. Each bolt only has one connection. With 3.5mm jacks, there are two connections: signal and ground. Like banana jacks, this bolt system keeps the ground internal, which means my patch cables can be made out of anything that conducts electricity, and I only need one wire.
  • Easy to find. If I really want to make a new module and I’m out of jacks, I just go to any hardware store and buy more. No need to spend an arm and a leg buying audio jacks at a big box store or waiting weeks for them to arrive by mail.
  • Durable. There are no moving parts, nothing to break! Aside from the possibility of rust, these bolts will never break.
  • Multiple connections per bolt. In the modular world, folks are usually cautioned against connecting multiple patch cables together instead of using a buffered mult. I pretty much disregard this advice and connect as many alligator clips to bolts as I like. Sometimes this does cause issues, and in those cases I use one of my various buffer or amplifier modules. (Not all of my modules have buffered outputs, but the ones that do don’t seem to mind multiple connections)

How do you power the synth?

I currently use two “wall wart” power supplies. One is a 20V AC adapter that goes into a little circuit to spit out positive and negative voltages (+9V and -9V). The other supply is a regular 9V DC adapter that I plug directly into the synth (no extra circuits, conditioning, or anything else).

How does the power get to each rack and module?

At first I tried a variety of approaches, mostly using different kinds of connectors to plug modules into the power (a lot like commercial modular systems work). Eventually I abandoned that approach and went with an infinitely simpler method.

  • I affix two to four metal deck screws directly into each wood case. (Two for racks that only have positive power and ground, four for racks that have +9V, -9V, +5V, and ground.)
  • Each module has one to three stranded wires hanging off, and these wires are wrapped around the metal deck screws. (One for modules that only need ground, two for positive and ground, three for positive, negative, and ground.)
  • The deck screws, in turn, are wired to CAT5 jacks wedged into the wood cases, held in place with yet more screws. At one point I had an epiphany: I needed a way to move 4 different signals around the synth, I had a ton of old ethernet/CAT5 cables that I wasn’t using, and I found a bunch of CAT5 jacks leftover from the construction of our house. When it occurred to me that I could use any type of wire for my synth, I tried wiring up an old ethernet cable… and it worked! I also love the idea that my synth has CAT5 jacks, I just have to make sure not to plug it into a router.
  • Each rack has two CAT5 jacks so I can daisy-chain racks together. I cut off the power plugs from both wall warts and soldered 3.5mm plugs to them, and created two power modules with 3.5mm jacks. The important thing here is to make sure I don’t accidentally plug a power plug into an audio device! Because not every rack has power, I daisy-chain them together.

Buying stuff

Where do you get your components/parts/materials?

Many different places! In order of frequency:

How much did it cost to build?

It’s a bit tough to calculate what I spent, as many components were salvaged from broken devices (some from a TV I found in the woods), and when I buy electronic components not all of them immediately go into the synth.

That said, I think a conservative guess is that my entire synthesizer cost under $500 (so far). I think it probably is much less, maybe closer to $300.

That’s not a small amount of money, but if you were to buy commercial modules to make a system as large as mine, it would cost you considerably more than $500. Granted, commercial modules generally have more functionality-per-module than my very simple circuits, but still… If we’re going by size, a giant modular like mine might set you back a few thousand dollars off the shelf.

Each module, as a very rough estimate, costs between $1 and $20 to build. A very large number of my modules are extremely simple and only consist of a few components; perhaps some capacitors, resistors, a single IC, and a handful of LEDs. For example:

  • The diode “AND” module is 4 diodes (at around $0.05 per diode, maybe cheaper), 5 bolts, an oak panel, and some wire. It’s totally passive, meaning it doesn’t require any power supply.
  • My low pass gate module is 2 LEDs, a capacitor, and a few resistors, oak panel, bolts, and some wire. Definitely didn’t cost more than $5 to build, and I use it in almost every patch.
  • A large number of my modules are CMOS ICs wired directly to the panel, more or less, usually with some LEDs thrown in. Most CMOS ICs cost between $0.25 and $2, the vast majority of the ones I use are around $0.50. Even big modules like my multiplexor are pretty simple and cheap: 8 LEDs, bolts, wire, oak panel, and a $1 integrated circuit (IC).

Of course, these numbers don’t take into account shipping costs or all the components I accidentally fried on the breadboard. They definitely don’t include the hours of research, study, learning, and experimentation… but as I mentioned above, I had the desire to learn and the free time to do it!

Check out my full list of modules here

Safety

Don’t you get shocked when touching the bolts?

No! To be honest I’m not entirely sure why. Even if I use my body as a patch cable – touching two fingers on different modules – I don’t get shocked. I think it’s because the voltage and current are both so low. Perhaps somebody with more electronics understanding could explain why!

Aren’t you worried about starting a fire, especially with those wood panels?

I would have thought wood panels plus electronics would be a bad idea, but when I learned about Bastl Instruments and their beautiful oak panels, I decided to give it a shot myself. Nothing in my synth gets very hot, and I’ve only created sparks while experimenting on the breadboard. By the time anything goes into the rack it is decidedly spark-less! Additionally, everything in my synth is low voltage, at most +9V.

Getting Started in Synth DIY

What electronics experience did you have that made you think you could possibly build a synthesizer from scratch?

None. Perhaps I was naive, arrogant, or more likely both! I have degrees in music and Spanish, and absolutely zero training in electronics. In fact, before I started I didn’t know how to read a schematic, I couldn’t identify electronic components, and I am extremely bad at math (possibly related to my synesthesia).

I did, however, have a burning desire to learn, a boundless enthusiasm for building my own synthesizer, and plenty of free time.

I would suggest that those things and a good internet connection is all you need to get started.

What else do I need?

  • Soldering iron
  • wire
  • breadboard
  • components – I started with a kit like this and a handful of ICs

What ICs should I buy?

Almost every IC I use is a CMOS IC. They are cheap, can be run on a wide range of voltages, and they are generally very forgiving of mistakes. Indeed, there is an entire movement of DIY electronics focused on CMOS stuff– Lunettas! This approach has greatly informed my own approach to synth DIY.

Check out this amazing Lunetta getting started guide. It’s a great place to start!

Here are some of my favorite integrated circuits (ICs):

  • 4017 – 10 step sequencer, or divider, plus more
  • 4040 – divider
  • 4069, 4049 – analog inverters that can also be used as amplifiers and distortion
  • 40106 – with some other components, make 6 oscillators with one chip
  • 4060 – analog switch. Combine it with a 4017 for a sequential switch. Lots of cool things you can do with it
  • 4051 – multiplexor. Hard to explain what it does, just get some and experiment.
  • 555 and 556 “timer” chips – the classic lofi oscillator chips. A nice place to start
  • LM342, LM741 – op amps. Indispensable in synths.
  • LM386 – power amp chip, use it to power speakers, spring reverb, or make nasty distortion

Synth DIY online resources

Circuits

Books

  • Nicholas Collins “Handmade Electronic Music” – A must-read for DIY electronics! Collins’ experimental tone really resonates with me, and there are tons of great and very simple circuits throughout the book
  • Forrest Mims “Getting Started in Electronics” –  a really great tutorial on reading schematics, identifying electronic components, and making some simple circuits
  • Craig Anderton “Electronic Projects for Musicians” – a little dated but still full of great info

2 responses

  1. awesome! you can **totally** do it! there are many very simple circuits that can add nice functionality to your existing commercial stuff. things like passive diode “ring modulators” or simple low pass gates are very easy to build

  2. Thank you for writing these pages. Very inspiring! Your Lunetta synth actually plays mostly in tune, unlike the others I hear. What’s the secret?

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