An Open Source Toy Synth

If you thought the future of electronic musical instruments was massive Emerson-class modular synths, giant MPCs with pads the size of Dance Dance Revolution machines, or hilariously expensive polysynths, you couldn’t be more wrong. The future is, effectively, toys. Those tiny little Korgs you can stuff in your pocket are selling like hot cakes, and Pocket Operators are king of the hill. One of the more interesting musical toys is the Organelle, an aluminum enclosure with maple buttons laid out in a keyboard configuration. It’s a synth, it’s a sound engine, and it does produce some interesting noises. All the software is Open Source, but the hardware isn’t. That leaves it up to someone else to make the hardware for the rest of us. That’s exactly what [mitchell] is doing for his Hackaday Prize entry.

The core of this build is a Nanopi Neo Core, or basically an Allwinner H3 breakout board with 256 MB of RAM running at 1.2 GHz. This runs the basic Organelle scripts, and has all the drivers to become a MIDI device. Added to that, there’s a DAC, a small TFT screen, an STM32F103 for reading the buttons, encoders, and pots, a sound card, a USB hub IC, and a battery torn from a Kindle.

The idea for this project is to have something along the lines of the Teenage Engineering OP-1, another of the very fancy ‘toy’ synths, but also to build something that anyone else can build. [mitchell] is just about there, and the prototype PCB he made actually works. There’s still a lot more work to do, but this is an exceptionally interesting project we can’t wait to see hit prime time.

Don’t Forget Your Mints When Using This Synthesizer

While synthesizers in the music world are incredibly common, they’re not all keyboard-based instruments as you might be imagining. Especially if you’re trying to get a specific feel or sound from a synthesizer in order to mimic a real instrument, there might be a better style synth that you can use. One of these types is the breath controller, a synthesizer specifically built to mimic the sound of wind instruments using the actual breath from a physical person. Available breath controllers can be pricey, though, so [Andrey] built his own.

To build the synthesizer, [Andrey] used a melodica hose and mouthpiece connected to a pressure sensor. He then built a condenser circuit on a custom Arduino shield and plugged it all into an Arduino Mega (although he notes that this is a bit of overkill). From there, the Arduino needed to be programmed to act as a MIDI device and to interact with the pressure sensor, and he was well on his way to a wind instrument synthesizer.

The beauty of synthesizers is not just in their ability to match the look and sound of existing instruments but to do things beyond the realm of traditional instruments as well, sometimes for a greatly reduced price point.

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OTTO: A Pi Based Open Source Music Production Box

Want an open source portable synth workstation that won’t break the bank? Check out OTTO. [Topisani] started OTTO as a clone of the well-known Teenage Engineering OP-1. However, soon [Topisani] decided to branch away from simply cloning the OP-1 — instead, they’re taking a lot of inspiration from it in terms of form factor, but the UI will eventually be quite different.

On the hardware side, the heart of the OTTO is a Raspberry Pi 3. The all-important audio interface is a Fe-Pi Audio Z V2, though a USB interface can be used. The 48 switches and four rotary encoders are wrangled by a pair of Arduino pro micros which pass the data on to the Pi. Data is related to the user through a 320×200 LCD.

The software is being written from scratch in C++17. If you’re not a hardcore C++ developer, don’t worry. The synth engines, audio effects, and other DSP software is written in Faust, which is a bit easier to learn.

OTTO is actively being developed, with synth engines already running, a prototype in progress, and fleshed out guidelines for programming the UI. If you’re into creating music, this one is worth checking out, as is Zynthian, another Raspberry Pi based synth.

Cigar Box Synth is a Fun Time

It’s fair to say that the groovebox market has exploded. Store shelves are overflowing with the umpteenth releases from KORG’s Volca line and the latest Pocket Operators. These devices often feature a wide array of tones in an enticingly compact and attractive package, but is it possible to build something similar at home? As [lonesoulsurfer] relates, it certainly is.

The Cigar Box Synth is, well… a synth, built in a cigar box. Based upon a 555 & 556 timer, and a 4017 decade counter, it provides a wealth of beepy goodness all crammed into a neat wooden package. We dig the cigar box form factor, as it’s a readily available wooden box often finished in an attractive way, and readily reworkable for all kinds of projects.

Sound is controlled with three master potentiometers, and there are four separate potentiometers to set the note for each of the four steps in the sequence. While its melodic abilities are limited to just four notes, it’s certainly something fun to play with and can act as a great jumping off point for further electronic experimentation in this area.

It takes us back to our guide on building DIY logic-based synthesizers – read on!

Synthbike Rolls To The Beat

Modular synthesizers are some of the ultimate creative tools for the electronic musician. By experimenting with patch leads, knobs and switches, all manner of rhythmic madness can be conjured out of the æther. While they may overflow with creative potential, modular synths tend to fall down in portability. Typically built into studio racks and composed of many disparate modules, it’s not the sort of thing you can just take down the skate park for a jam session. If only there was a solution – enter the madness that is Synth Bike.

Synth Bike, here seen in the 2.0 revision, impresses from the get go, being built upon a sturdy Raleigh Chopper chassis. The way we see it, if you’re going to build a synth into a bicycle, why not do it with some style? From there, the build ratchets up in intensity. There’s a series of sequencer modules, most of which run individual Arduino Nanos. These get their clock from either a master source, an external jack, or from a magnetic sensor which picks up the rotation of the front wheel. Your pace dictates the tempo, so you’ll want to work those calves for extended raves at the park.

The features don’t stop there – there are drums courtesy of a SparkFun WAV Trigger, an arcade button keyboard, and a filter board running the venerable PT2399 digital delay chip. It’s all assembled on a series of panels with wires going everywhere, just like a true modular should be.

The best thing is, despite the perplexing controls and arcane interface, it actually puts out some hot tunes. It’s  not the first modular we’ve seen around these parts, either.


Bringing Guitar Synthesis To The Microcontroller

If you’re working with audio in an embedded environment, the best option for years now has been the Teensy 3 microcontroller board. This choice has mostly been due to its incredible power and audio libraries, but until now we really haven’t seen a stompbox-style interface that used the Teensy to its fullest extent. Now we have, in [Wolkstein]’s GitSynth, everything you could want in a synthesizer that processes the signals from an electric guitar.

The core of this build is a Teensy 3, and all the audio goodies that come with that. Also included is a USB MIDI and audio interface, smartly both attached to a panel-mount USB-B connector on the back of the stompbox. Other controls include a single mono in jack for guitars and synths, two mono out jacks for stereo-ish output, a bunch of footswitches for bypass, tap tempo, preset selection, a jack for an expression pedal, and some buttons to move around the LCD user interface.

While putting a powerful microcontroller in a stomp box for is a project we’ve seen many times, this project really shines with the MIDI GUI that’s built for a device with a real display and a mouse. [Wolkstein] built a PyQt-based app for this synth, and it’s a plethora of buttons and sliders that looks similar enough to a real synthesizer. There’s enough configurability here for anyone.

You can check out the demo video (in German, but auto-translate subtitles exist) below.

Thanks [Mynaru] for the tip!

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Learn What Did and Didn’t Work In this Prototyping Post-Mortem

[Tommy] is a one-man-shop making electronic musical things, but that’s not what this post is about. This post is about the outstanding prototyping post-mortem he wrote up about his attempt to turn his Four-Step Octaved Sequencer into a viable product. [Tommy] had originally made a hand-soldered one-off whose performance belied its simple innards, and decided to try to turn it into a product. Short version: he says that someday there will be some kind of sequencer product like it available from him, “[B]ut it won’t be this one. This one will go on my shelf as a reminder of how far I’ve come.”

The unit works, looks great, has a simple parts list, and the bill of materials is low in cost. So what’s the problem? What happened is that through prototyping, [Tommy] learned that his design will need many changes before it can be used to create a product, and he wrote up everything he learned during the process. Embedded below is a demo of the prototype that shows off how it works and what it can do, and it helps give context to the lessons [Tommy] shares.

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