A Mess Of Wires Turned Into An Analog Synth

Over on YouTube, [GumpherDM3] built one of the greatest musical projects we’ve seen in a long time. It’s an analog synthesizer that is one of a kind. It’s going to stay one of a kind, too: no one would ever want to copy this mess of wires and perfboard that was successfully turned into a complete musical instrument.

The design of this synth is what you would expect from something that draws its inspiration from semimodular synths such as the Minimoog and Korg MS20. There are four VCOs on this synth, two audio and two used for the LFOs. A four-pole low pass filter, VCA, and two envelope generators round out the purely analog portion of the build. There’s an arpeggiator in there too, which makes for a really great demo video (below).

Inside, this is a true analog synth with the VCOs, filter, and VCA built around the LM13700 transconductance amplifier. The build log shows these chips spread out around half a dozen breadboards before being plugged into sockets soldered to handwired perf board. This synth is a one of a kind instrument – no one would want to build this thing twice.

Additional features include an Arduino with a MIDI in port sending out CV signals to the analog part of the synth. This thing has everything you would expect from a modern take on an analog synthesizer, and it sounds good, too.

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Hackaday Links: January 25, 2015

Misumi is doing something pretty interesting with their huge catalog of aluminum extrusions, rods, bolts, and nuts. They’re putting up BOMs for 3D printers. If you’ve ever built a printer with instructions you’ve somehow found on the RepRap wiki, you know how much of a pain it is to go through McMaster or Misumi to find the right parts. Right now they have three builds, one with linear guides, one with a linear shaft, and one with V-wheels.

So you’re finally looking at those fancy SLA or powder printers. If you’re printing an objet d’arte like the Stanford bunny or the Utah teapot and don’t want to waste material, you’re obviously going to print a thin shell of material. That thin shell isn’t very strong, so how do you infill it? Spheres, of course. By importing an object into Meshmixer, you can build a 3D honeycomb inside a printed object. Just be sure to put a hole in the bottom to let the extra resin or powder out.

Remember that episode of The Simpsons where Homer invented an automatic hammer? It’s been reinvented using a custom aluminum linkage, a freaking huge battery, and a solenoid. Next up is the makeup shotgun, and a reclining toilet.

[Jan] built a digitally controlled analog synth. We’ve seen a few of his FM synths VA synths built from an LPC-810 ARM chip before, but this is the first one that could reasonably be called an analog synth. He’s using a digital filter based on the Cypress PSoC-4.

The hip thing to do with 3D printers is low-poly Pokemon. I don’t know how it started, it’s just what the kids are doing these days. Those of us who were around for Gen 1 the first time it was released should notice a huge oversight by the entire 3D printing and Pokemon communities when it comes to low-poly Pokemon. I have corrected this oversight. I’ll work on a pure OpenSCAD model (thus ‘made completely out of programming code’) when I’m sufficiently bored.

*cough**bullshit* A camera that can see through walls *cough**bullshit* Seriously, what do you make of this?

An ARM-Based DSP Modelling Synth


The great analog synths of Moog, Oberheim, Sequential Circuits, and more modern version from Doepfer are renouned for their sound, the sheer majesty of a rack full of knobs and plugs, and of course the price. Analog synths are simply expensive to build, and given that aficionados even scoff at digitally controlled oscillators, require a lot of engineering to build. [Jan]’s DSP-G1 isn’t like those analog synths – it uses microcontrollers and DSP to generate its bleeps and boops. It is, however, extremely cheap and sounds close enough to the real thing that it could easily find a home between a few euroracks and CV keyboards.

plugThe heart of the DSP-G1 is a micro from NXP modeling an analog synthesizer with 15 digitally controlled oscillators with Sine, Triangle, Pulse and Saw outputs, a low frequency oscillator, two envelope filters, and a low pass filter, or about the same accouterments you would find in a MiniMoog or other vintage synth from the 70s. Since this is basically a synth on an NXP LPC-810, [Jan] has packaged it in something akin to a MIDI to 3.5mm cable adapter: Plug a MIDI keyboard into one end, an amp into the other, and you have a synth smaller than the MIDI Vampire, an already impossibly small music creation tool.

[Jan] has a few more versions of his little DSP device with varying amounts of knobs available on his indiegogo campaign. The DSP-Gplug is the star of the show, though, provided you already have a MIDI keyboard with a few knobs for the required CC messages. Videos and sound demos below.

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The Solafide Forbes Nash Organ


A few years ago, [Chad] wanted to build a musical instrument. Not just any musical instrument, mind you, but one with just intonation. Where modern western music maps 12 semitones onto a logarithmic scale per octave, just temperament uses ratios or fractions to represent notes on a scale. For formal, academic music, it’s quite odd especially if you’re building an analog synth for this temperament. In a remarkable three-part write up (parts one, two, and three), [Chad] goes over the creation of this extremely strange musical instrument.

The idea was for this synth to produce sine waves for each of the tones on the just intonated scale. [Chad]’s initial experiments led him down the path of using strings and magnetic pickups to produce these sine waves. These ideas were initially discarded for producing sine waves electronically on dozens of different homemade PCBs, one for each tone.

The keys are an extremely interesting design, working on the principle of light from an LED shining on a photodetector, blocked by a shutter on a spring-loaded key made on a laser cutter. The glyphs on the keys seen above actually have meaning; each one describes the ratio of the interval that key plays, encoded in some schema that isn’t quite clear.

What does it sound like? There’s three videos below, but because this synth isn’t tuned to the scale you’re used to, it doesn’t sound like anything else you’ve heard before.

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Building a synth on a breadboard


Building an analog synth is a challenge, but with the [Tymkrs] protosynth, it’s easier than ever. It’s a 25-key keyboard attached to a stack of solderless breadboards to make analog synth prototyping a snap.

Earlier, [Tymkrs] acquired a whole bunch of solderless breadboards and decided to put them to use by making a component-level modular synth. The earlier incarnation tied each key on the keyboard to a few wires behind the breadboard and tied them in to a shift register so they could be read with a Propeller dev board loaded up with a Commodore SID emulator. The new version keeps the very clean through-the-back keyboard connector, but this time the [Tymkrs] are adding a few more components that add a sequencer setup and a rotary encoder.

The eventual goal for this really cool breadboard synth is to explore the world of Moogs, Arps, and other analog synths easily on a breadbaord. The [Tymkrs] have already put together a breadboard-compatible low pass and high pass filter. While there’s still a lot of work to be done to make an analog synth a reality, the [Tymkrs] are off to a great start.

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Sinister Tone Generator brings the bass


[RichDecibels] wrote in to share a new device he built called the “Sinster Tone Generator”. It’s basically a bass drone synthesizer that uses two pairs of heterodyning oscillators to generate the output. If you swing by his site, he has a long audio demo of the device in action with a bit of reverb and filtering applied to enhance the sound. After listening, we agree that it sounds pretty sinister!

The device is relatively small and handsomely packaged in a plastic project box he had custom cut by Ponoko. [Rich] says that this particular unit is a one-off that he has produced for a charity auction, and that bidding is open through Sunday if you really want to get your hands on it. If you happen to have the time to build one yourself, he has uploaded schematics and layout files to his site (as usual), so feel free to stop by and grab a copy.