analog synth

13 Articles

The synth in question in its acrylic case.

DIY Polyphonic Synth Sings In 8-Part Harmony

November 22, 2025 by 9 Comments

There’s just something about an analog synthesizer. You’d think that for electronic music, digital sampling would have totally taken over by now, but that’s really not true. The world of analog synths is alive and well, and [Polykit] has a new, open-source polyphonic synthesizer to add to the ever-growing chorus of electronic instruments.

The analog part is thanks to the eight identical voice cards that plug into the machine’s mainboard: each one has a voltage controlled oscillator to generate tones, an envelope generator, multiple voltage-controlled amplifiers, and even a pole mixing filter which is also, yes, voltage controlled. Each voice card outputs stereo, and yes, there are controllable mixing circuits for left and right output.

All that voltage control means a lot of lines from digital-to-analog converters (DACs), because while this is an analog synth, it does have a MIDI interface, and that means that a microcontroller needs to be able to speak voltage. In this case, the brains are an ATmega2560. Instead of stacking the board with enough expensive DACs to interpret the MCU’s digital signals, [Polykit] is instead is using some clever tricks to get more work out of the one DAC he has. Some things get tied together on all eight voices, like the envelope parameters; other values are run through a demultiplexer to make the most possible use of the analog lines available. Of course that necessitates some latching circuitry to hold the demuxed values on those lines, but it’s still cheaper than multiple high-quality DACs.

It’s a well-thought out bit of kit, down to the control panel and acrylic case, and the writeup is worth reading to get the full picture. The voice cards, main board and control board all have their own GitHub repositories you can find at the bottom of the main page. If you’re into video, [Polykit] has a whole series on this project you might want to check out on Makertube; we’ve embedded the first one below.

If you want to get your toes wet in the wonderful world of synthesizers, this library of seventy synths is an amazing place to start, because it has great simple projects.

Thanks to [Polykit] for the tip!

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DIY Analog Synth Looks Like Fun

December 10, 2021 by 11 Comments

The relative ease of building the individual components that make up an analog synth make it very tempting to DIY your own. That’s what [Albert Nyström] did and the result is this great looking, and great sounding, analog synth.

The VCOs in his monosynth are based around the AS3340 VCO chip, which is a clone of the Curtis Electromusic Specialties‘ CEM3340 chip (used in machines such as the Oberheim OB-Xa, the Roland Jupiter-6, and the Sequential Circuits Prophet-5 among others.) The voltage controlled filters are based on Moritz Klein’s VACTROL based VCF circuits, and the envelopes based on Thomas Henry’s 555 envelope circuits (Google searches will dig those up pretty quickly, as well as schematics for builds using the CEM chip.) Finally, the keyboard is a donor from an Arturia Keystep. While there are no step-by-step build instructions, or a schematic, we do have some info about the instrument. As you can see from some of the gut shots, it should be fairly easy to figure how [Albert] has put everything together. Or not.

Even if the internals are a bit wild, the end result is a great looking monophonic synth that does pretty much everything you’d need. If you feel the itch to wire a bunch of components together and make one yourself, there are messier ways to go about it. Or maybe you’d prefer to go the digital route? Either way, synths are a ton of fun to build and to play.

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Cassette Synth Plays With Speed Control

December 7, 2020 by 10 Comments

Tape may not sound that great compared to vinyl, but cassette players can be tons of fun when it comes to making your own music. See for instance the Mellotron, or this relatively easy DIY alternative, [Rich Bernett]’s Cassettone cassette player synth.

The Cassettone works by substituting the trim pot that controls the speed of the tape player’s motor with a handful of potentiometers. These are each activated with momentary buttons located underneath the wooden keys. In the video after the break, [Rich] gives a complete and detailed guide to building your own. There’s also a polished Google doc that includes a schematic and the pattern pieces for making the cabinet.

Speaking of which, isn’t the case design nice? It’s built out of craft plywood but aged with varnish and Mod-Podged bits and bobs from vintage electronics magazines. This really looks like a fun little instrument to play.

Would you rather control your tape synth with a MIDI keyboard? Just add Arduino.

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One Chip Does It All In This MacGuyver Synth

January 27, 2020 by 33 Comments

When you think of simple synths, what components come to mind? All you really need to make one is an oscillator, an amplifier, and some kind of input such that you can play different notes. Our favorite go-to for churning out square waves is probably the 40106 IC, which has six inverting Schmitt triggers, and then usually a 386 to amplify the output.

But it’s possible to go even simpler than that, and school is in session with [Jule] giving the lesson. [Jule]’s little analog synth uses a single IC for both the oscillator and the amplifier — a TL072 op-amp. The rest is made of purely discrete components.

[Jule] says those momentary switches are sub-par, and will add a vibrato effect if properly wiggled while pressed. To us, the buttons looks pretty nice, and much easier to jam out with than the ones with 1/8″ diameter actuators. Plus, whenever you press multiple buttons, the additive resistance unlocks the synth’s inner R2D2 voice. We really see no downsides here.

By default, this is an eight-button synth tuned to C major. But there’s a surprise — you can plug different capacitors into a piece of header and change the octave on the fly. Check it out after the break.

Making pitch-correct frequencies requires weird resistor values, which we can usually satisfy with two resistors in series. But wait, what’s up with resistor values, anyway? And why do they have a color code?

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Hack My Wired Heart

June 12, 2019 by 3 Comments

Liner notes? Passé. In Berlin, the release of a special edition synth-wave record came with an accompanying experimental synthesizer called Wired Heart.

At the core of this adorable heart-shaped synth, designed by music technology enthusiast [tobi tubbutec], is the classic 74HCT14 chip with six Schmitt trigger oscillators. The bright red PCB has eight gold touch and humidity sensing pads that activate and modulate these oscillators. As well as changing the sounds by playing with pressure and conductive liquids you can use the six sets of header pins on board to plug in your own components for noisy experimentation. Wired Heart ships with LEDs, photoresistors and a potentiometer, but we’ve also plugged our own DIY fabric pressure sensors into this synth to make some excellent electronic sounds.

In the Hackaday.io post linked above, [tobi tubbutec] walks us through a number of the circuit design decisions he made while prototyping his “cardiotronic human-touch hexoscillatric stereo esoteric snythespacer”. We enjoyed his creative and sometimes unconventional designs, from his inclusion of non-functioning traces for aesthetic reasons to his chosen method of hard syncing — injecting a small pulse of one oscillator into the other. If you want to examine his layout in more detail, [tobi tubbutec] has helpfully included the KiCad schematic file in his write up.

This adorable, hackable synth caught our eye at this year’s SuperBooth — an annual indie electronic music conference in Berlin that’s well worth checking out if odd noises and handmade electronics are your thing —  but it’s recently been listed on Tindie too. To listen to the upbeat synth-wave record Wired Heart originally shipped with, visit the artist Hyboid’s bandcamp.

If you’re interested in experimental musical instruments and synthy chip tune you’ll also love [jarek319]’s Sega Genesis synthesiser.

Check out a demo of the Wired Heart synth in the video after the break.

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Analog Synth, But In Cello Form

November 3, 2018 by 8 Comments

For one reason or another, electronic synthesizing musical instruments are mostly based around the keyboard. Sure, you’ve got the theremin and other oddities, but VCAs and VCFs are mostly the domain of keyboard-style instruments, and have been for decades. That’s a shame, because the user interface of an instrument has a great deal to do with the repertoire of that instrument. Case in point: [jaromir]’s entry for the Hackaday Prize. It’s an electronic analog synth, in cello form. There’s no reason something like this couldn’t have been built in the 60s, and we’re shocked it wasn’t.

Instead of an electrified cello with a piezo on the bridge or some sort of magnetic pickup, this cello is a purely electronic instrument. The fingerboard is metal, and the strings are made of kanthal wire, the same wire that goes into wire-wound resistors. As a note is fingered, the length of the string is ‘measured’ as a value of resistance and used to control an oscillator. Yes, it’s weird, but we’re wondering why we haven’t seen anything like this before.

How does this cello sound? Remarkably like a cello. [jaromir] admits there are a few problems with the build — the fingerboard is too wide, and the fingerboard should probably be curved. That’s really an issue with the cellist, not the instrument itself, though. Seeing as how [jaromir] has never even held a cello, we’re calling this one a success. You can check out a video of this instrument playing Cello Suite No. 1 below. It actually does sound good, and there’s a lot of promise here.

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