An RPi-Powered Multi-DX7/TX816 Style Synth

May 7, 2023 by Dave Rowntree 16 Comments

[Kevin] over at Simple DIY ElectroMusic Projects has released a complete DIY modular design for simulating the classic 80s Yamaha TX816 DX/FM modular digital synthesizer. This beast of a synth was used by the cool bands of the 80s as well as TV studios, and ownership of the original machine is an expensive investment. But with the power of modern hackable electronics, and the MiniDexed firmware running bare-metal on a Raspberry Pi getting access to a compatible synth doesn’t have to break the bank.

[Kevin] wanted to emulate the look and feel of the original TX816 aesthetic, developing a custom PCB handling the user interface for four of the eight channels, and a second acting as an interface to the Raspberry Pi using a Pico. Also sitting on this PCB is the GY-PCM5102 I²S DAC, and the MIDI connectors needed to connect to the system controller. Both PCBs, including a PCB-based front panel, were developed with KiCAD. The firmware for the Pico part of the system can be found on the firmware GitHub. The video demo (embedded below) shows off the system running a very 80s-sounding rendition of Holst’s famous ‘Jupiter’ from the planet series, and we all agree it sounds pretty sweet. For a complete rundown of the build, here are the links for the blog series for ease of access: Intro, PCBs, Panel, Build Guide, Mechanical, Pico/TX816 IO code, and finally usage. Phew!

If MiniDexed sounds familiar, that is because we featured another of [Kevin’s] earlier MiniDexed projects a little while ago.

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Rope Core Drum Machine

November 6, 2022 by Jonathan Bennett 7 Comments

One of our favorite musical hackers, [Look Mum No Computer] is getting dangerously close to building a computer. His quest was to create a unique drum machine, inspired by a Soviet auto-dialer that used rope core memory for number storage. Rope memory is the read-only sibling to magnetic core memory, the memory technology used to build some beloved computers back in the 60s and early 70s. Rope core isn’t programmed by magnetizing the ceramic donuts, but by weaving a wire through them. And when [Look Mum] saw the auto-dialer using the technology for a user-programmable interface, naturally, he just had to build a synth sequencer.
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Mechanical Relay Percussion In A Eurorack Format

September 15, 2022 by Lewin Day 5 Comments

There are plenty of analog and digital synthesis modules available in Eurorack format. But how about one that actually does physical percussion while capturing the output at the same time? The VU Perc Relay module does just that.

The concept is simple. Eurorack control voltages are fed to a VU meter, which swings about and makes noise when the needle hits a copper strip. This strip is connected to a piezo element which captures the sound. There’s also a relay that gets triggered under such conditions, with that sound also captured by a piezo element. Thus, the input control voltages create real percussion noises with the VU meter and relay, and then capture them for output to the rest of the rack.

Having actual physical sound devices in a compact Eurorack module is neat. The fact that it’s transparent is even cooler, as it lets you see the percussion in action. Notably, the physical nature of this module means you’ll want to place some bubble wrap or other isolating material under your rack when performing on stage with a PA. Otherwise, you risk getting feedback through the piezos.

We see plenty of good Eurorack gear around these parts, like this useful wireless MIDI connection. Video after the break.

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A computer program written in basic next to a modular synthesizer with many switches and lights

Modular Synth Pairs Perfectly With The Apple II

February 4, 2022 by Chris Wilkinson 4 Comments

We have a soft spot for synthesizers – seriously, who doesn’t? So when [Joshua Coleman] combined his retro-looking DIY modular synth with the equally retro Apple II computer, we just had to share it with you.

The two machines are paired using a vintage digital-to-analog logic controller pack. This DAC was originally used to control model trains using your Apple II – something that we now desperately need to see in action. The pack can output voltages between 0 and 2.55 V at 8-bit resolution (or 256 steps), which is plenty for a retro synth.

With the card installed in Slot 7 of the Apple II and the DAC wired through to the synth’s CV/gate, it’s then a trivial matter of writing POKE statements in Applesoft BASIC to control the synth. The video after the break demonstrates playing a simple melody, as well as how one might use the Apple II keyboard to ‘play’ the synth in real time.

If you’re interested in building your own, the video below has all the information needed, as well as helpful advice on where to find a DAC for your preferred model of vintage computer. If all that doesn’t tickle your musical fancy, make sure to check out our coverage on the Game Boy MIDI synth, or perhaps this peculiar synth and visualizer combo.

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This Is The Delay Pedal You Can Build Yourself

April 10, 2019 by Brian Benchoff 33 Comments

If you’re looking to make money in electronics, there’s no better market than guitar pedals and modular synths. The margins are high, and all the consumers are otakus who will spend outrageous amounts of money chasing the next big thing. The products are just one step above audiophile wank with zero oxygen cables, and if your opamp sounds ‘more transparent’, you’re going to make a fortune, never mind how something can sound more transparent, whatever that is to begin with.

If you want to do something really cool, build a delay, because everyone needs another delay. If you want to build the latest in delay technology, just grab a PT2399 chip. That’s what ElectroSmash did with their Open Source Time Manipulator delay. Everything’s right there, all the parts of the circuits are described, and you too can become an effects pedal engineer.

This pedal is based on the PT2399 chip from Princeton Technology, a digital delay chip that can be used with something that sounds like an old-school bucket brigade chip or something resembling a tape echo. As a digital chip, you’ve also got the clean, clear sounds of a digital delay, with just a few tweaks of the circuit. We’ve taken a look at the PT2399 before, but surprisingly not many people are sharing their secrets.

The circuit for the ElectroSmash Time Manipulator is built around the ATMega328, the same chip in the Arduino Uno, with two PT2399s that can be configured to operate in serial or parallel for everything from a slapback echo to a 600ms digital delay. If you set everything right, you can get choruses, reverbs, or some psychobilly flange-ish sounds.

The entire circuit is open, with a board designed in KiCad, the code is right there written in C, and the only hard-to-replicate tech is the PT2399 chip itself, which can be had from the usual vendors for less than a dollar a piece. It’s a great pedal, and be sure to check out the video below.

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Eurorack Gets A Wireless MIDI Connection

February 21, 2019 by Lewin Day 4 Comments

Modular synthesizers have been around since the early 1960s, delivering huge tonal possibilities from their impressive and imposing patchbays. In 1996, the Eurorack standard was launched, and has become the go-to choice for enthusiasts new to the world of modular synthesis. [Rich Heslip] is just one such enthusiast, and has brought Bluetooth MIDI to Eurorack with his Motivation Radio module.

[Rich]’s module is built around the ESP32, which provides plenty of processing power, along with all the necessary radio hardware to communicate over Bluetooth. The unit packs plenty of connectivity into an 8HP wide panel, with four gate inputs and outputs, four CV inputs and outputs, and serial MIDI in and out.

Thanks to its Bluetooth connection, Motivation Radio makes it easy to pass note and gate data into a Eurorack setup, and can be used with the wide variety of tablet and smartphone MIDI software on offer. If you’re eager to build your own, PCB and panel designs are available courtesy of [jakplugg] and [Rich] has shared the software on Github.

Of course, if you prefer MIDI over USB, [little-scale] has the build for you. Video after the break.

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Synthbike Rolls To The Beat

April 26, 2018 by Lewin Day 11 Comments

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.