MIDI to CV The DIY Way

MIDI has been a remarkably popular interface since its inception way back in 1983. Based on existing serial interfaces, and with a broad enough set of features, it remains the defacto standard for communication between musical gear. However, older gear and many modular synths simply don’t grok digital data, instead using analog control voltages to get the job done. Never fear, though – you can convert from one to the other with the goMIDI2CV.

It’s a simple device, hewn from an ATTINY microcontroller. MIDI signals are received at TTL voltage levels, and converted to output voltages by the ATTINY via use of the PWM hardware. A lowpass filter is added to remove the high-frequency content from the output signal.  A 6N138 optocoupler completes the project, to comply with the MIDI standard and ensure the device is not subject to any dangerous voltages from the hardware plugged in.

It’s a simple way to control older non-MIDI compliant hardware, and might make an old modular rig just that much more useful in the studio of today. We’ve seen similar builds before, like this combined CV and Gate converter. 

Eurorack Gets a Wireless MIDI Connection

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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Never Mind The Sheet Music, Here’s Spreadsheet Music

Nothing says Rockstar Musician Lifestyle like spreadsheet software. Okay, we might have mixed up the word order a bit in that sentence, but there’s always Python to add some truth to it. After all, if we look at the basic concept of MIDI sequencers, we essentially have a row of time-interval steps, and depending on the user interface, either virtual or actual columns of pitches or individual instruments. From a purely technical point of view, spreadsheets and the like would do just fine here.

Amused by that idea, [Maxime] wrote a Python sequencer that processes CSV files that works with both hardware and software MIDI synthesizers. Being Python, most of the details are implemented in external modules, which makes the code rather compact and easy to follow, considering it supports both drums and melody tracks in the most common scales. If you want to give it a try, all you need is the python-rtmidi and mido module, and you should be good to go.

However, if spreadsheets aren’t your thing, [Maxime] has also a browser-based sequencer project with integrated synthesizer ongoing, with a previous version of it also available on GitHub. And in case software simply doesn’t work out for you here, and you prefer a more hands-on experience, don’t worry, MIDI sequencers seem like an unfailing resource for inspiration — whether they’re built into an ancient cash register, are made entirely out of wood, or are built from just everything.

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Hackaday Links: January 27, 2019

Once again, Uber found a company to build their ‘air taxis’. This time it’s Boeing. While there are no details on the Boeing bird, I’m going to propose again that Uber buy the Santa Monica airport as a hub for their air taxi program; SMO is going to be shut down anyway, and this is the funniest reality that can come from the idea of an ‘air taxi’ program.

According to ancient astronaut theorists, one of the bigger problems with full-time tech YouTubers (think Dave and Fran here) is the insistence that YouTube suggests conspiracy theory videos as a related video. If you do a video teardown on Apollo flight hardware, you’re going to fall into the same category as people who believe the moon is hollow, people who believe the moon landing was faked, and recently, flat-earthers. This is a ‘bad move’ by YouTube because the Venn diagram of people who want to watch conspiracy videos and people who want to watch teardowns is two circles. It makes community engineering hard, and you get a lot of idiots on YouTube comments. YouTube is now changing the recommendation algorithm. There are other reasons YouTube is doing this, specifically relating to videos that aren’t about weird electronics, but we’re not going to talk about that here, thx.

This week was Winter NAMM, the National Association of… music, something something. That means you can go to Anaheim and check out all the musical instrument related stuff that will be released this year. Think of it as CES, only you don’t get the flu and want to murder everyone, and it’s about guitars and synths instead of Alexas duct taped to Roombas. Here’s what it was like last year, with the tl;dr being a wall of cabs, Euroracks everywhere, and the best way to get started in the industry is to buy some old trademarks, not by actually designing something new. Speaking of, here are some Kay reissues.

So, what’s cool at NAMM this year? Let’s do guitars first. Gibson’s 2019 lineup is not dumb, a reversal of the previous twenty years; There’s a Les Paul Standard with humbuckers or P90s, and there’s a TV Junior. Fender? There’s an acoustasonic Tele that was terrible the first time around, and it’s decidedly not terrible. The Electric XII is back, finally, and it’s even cooler than the Electric Six wait never mind it has a 1 11/16th nut. There is no Tele Plus with a Honda Goldwing emblem, but we make do with what we can. The pyramids are upside-downBuy a dookie pedal.

How about some synths?  Behringer is cranking out another clone, this time an Oberheim OB-Xa. Word on the street is that a 303 is on the horizon, but the vocoder is out now. The Odyssey exists, and the SH-101 clone comes with a handle so you can keytar it.  Guitars with Raspberry Pis? Could it be? Yes, Lucern Custom Instruments is collaborating with Tracktion to put a synth in a guitar. There’s a touchscreen BioTek 2 synth installed below the bridge. It’s like something [Matt Bellamy] would play, but it’s got a Raspberry Pi.

Elektron has a new samplerOh my god, the only way to make money in the instrument industry is to buy up trademarks. Well, trademarks and signature amps and guitars. Speaking of, where’s the signature Vangelis synths?

The news that will have the biggest impact a decade from now is the announcement that MIDI 2.0 is getting ready for release. New features include auto-config with DAWs, extended resolution, and expressiveness (to stop the Western hegemony on electronic music), and backward compatibility with MIDI 1.0.

This isn’t explicitly NAMM-related, but Eurorack is now a thing and [Jan] is always coming up with some interesting synths-on-a-chip. This time, it’s a drum machine in a Eurorack format. Is it based on anything? Not really, although it would go well in any Detroit acid track. Check out the video.

Open Source Fader Bank Modulates our Hearts

Here at Hackaday, we love knobs and buttons. So what could be better than one button? How about 16! No deep philosophy about the true nature of Making here; [infovore], [tehn], and [shellfritsch] put together a very slick, very adaptable bank of 16 analog faders for controlling music synthesis. If you don’t recognize those names it might help to mention that [tehn] is one of the folks behind monome, a company built on their iconic grid controller. Monome now produces a variety of lovingly crafted music creation tools.

Over the years we’ve written about some of the many clones and DIY versions of the monome grid controller, so it’s exciting to see an open source hardware release by the creators themselves!

The unambiguously named 16n follows in the footsteps of the monome grid in the sense that it’s not really for something specific. The grid is a musical instrument insofar as it can be connected to a computer (or a modular synth, etc) and used as a control input for another tool that creates sound. Likewise, the 16n is designed to be easily integrated into a music creation workflow. It can speak a variety of interfaces, like purely analog control voltage (it has one jack per fader), or i2c to connect to certain other monome devices like Ansible and Teletype. Under the hood, the 16n is actually a Teensy, so it’s fluent in MIDI over USB and nearly anything else you can imagine.

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Open Source Synthesizers Hack Chat

Matt Bradshaw is a musician, maker, and programmer with a degree in physics and a love for making new musical instruments. You may remember his PolyMod modular digital synthesizer from the 2018 Hackaday Prize, where it made the semifinals of the Musical Instrument Challenge. PolyMod is a customizable, modular synthesizer that uses digital rather than analog circuitry. That seemingly simple change results in a powerful ability to create polyphonic patches, something that traditional analog modular synths have a hard time with.

Please join us for this Hack Chat, in which we’ll cover:

  • The hardware behind the PolyMod, and the design decisions that led Matt to an all-digital synth
  • The pros and cons of making music digitally
  • Where the PolyMod has gone since winning the Musical Instrument Challenge semifinals

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Open Source Synthesizers Hack Chat and we’ll put that in the queue for the Hack Chat.

join-hack-chat

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, January 23, at noon, Pacific time. If time zones got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about. And don’t forget to check out the Modular Synth Discussion, a very active chat that digs into the guts of all sorts of modular synthesizers.

An Easy Way To MIDI Sync Your Eurorack Build

Eurorack synthesizer builds are known for a lot of things; simplicity isn’t necessarily one of them. However, not everything on a modular synthesizer build has to be inordinately complicated, a mess of wires, or difficult to understand. [little-scale] has built a neat and tidy module that might just find a place in your setup – the Chromatic Drum Gate Sync. The handy little device is based on a Teensy, and uses its USB MIDI libraries to make synchronizing hardware a snap.

The device has 12 channels, each responding to a single MIDI note. A note on message is used to set a gate high, and a note off message to set it low again. This allows very fine grained control of gates in a modular setup. The device can also output a variety of sync signals controlled by the USB MIDI clock – useful for keeping your modular rack in time with other digitally controlled synths.

It’s a build that espouses [little-scale]’s usual aesthetic – clean and tidy, with a focus on compactness. All the required details to build your own are available on Github.

We’ve seen the collision of [little-scale] and Teensy hardware before – with this rig playing 8 SEGA soundchips in unison.