How to build your very own string synth


The Eminent Solina is one of the fameous string synthesizers from the 70’s.
It is based on a paraphonic oscillator, a simple envelope and a phaser.


The oscillators in the original was a divide down structure where you generate the frequencys for the top octave and divide those down by modulo 2 for the rest of the octaves.

Paraphonic means it’s kind of polyphonic but shares some parts of the soundpath.
In this case it’s the envelope shared by all the keys played on the keyboard.

So what does it sound like?

Pretty nice eh?

Build instructions and the full source code for upload in an Arduino Nano can be found at the link to the right top on this page or this link:

My work on these free synthesizers is based on donations from people.
If you find the code useful, please consider a $3 donation  to keep future developments open source.

Donate $3

Chips for building DIY synthesizers can be found at:



33 Responses to “How to build your very own string synth”

  1. Chris Arndt Says:

    Very cool project! Is there a repository for the source code somewhere? Copy-an-paste from a PDF document is a bit error prone.

    • janostman Says:

      No there isn’t.
      The problem with this site is that I’m not allowed to put any other documents online but PDF’s

      Sorry but you have to live with this.

      Just Ctrl+A to mark the whole code and paste it into an .ino doc.

  2. Chris Arndt Says:

    Ok, thanks. But you could, for example, just paste the code into a Github Gist and link it here.

  3. astro-sound Says:

    This is great Jan, thanks for the write-up. I’ll definitely be building one of these soon after I’m done building a module using your VCDM chip.

    The gate/trig signal output is on D10, correct?

  4. genericpenguin Says:

    Ran through uncrustify and fixed a few lines wrapped by PDF. Compiles through Arduino app but have not tested.

  5. Tilman Baumann Says:

    Love the noob decals.

  6. Lolo4731 Says:

    Good work may!!
    Can work with Uno R3?

  7. inevitablecraftslabs Says:


  8. will wiffen Says:

    Where are the instructions etc, to the right of the page?

  9. steve Says:


    Any recommendations for a green noob to learn Synth basics from the ground up…? I am pretty proficient at C using the Arduino environment, but musically I am ignorant.


    • janostman Says:

      I dont’ really know of any good source for such.

      I’d say get my code running and learn how it works.

      Look at the mono synth code to make filters to your synth.

      You have to start somewhere.

  10. A Slew of Open-Source Synthesizers | Hackaday Says:

    […] has also built up a full-fledged string synthesizer keyboard out of just an Arduino Nano. It’s patterned on the Eminent Solina String Ensemble, and […]

  11. A Slew of Open-Source Synthesizers | Technology News Says:

    […] has also built up a full-fledged string synthesizer keyboard out of just an Arduino Nano. It’s patterned on the Eminent Solina String Ensemble, and we’ve […]

  12. Robin Says:

    Really great project!
    I just built up the solina synth on breadboard and it sounds great on its own, but running it through a slowly modulated moog-filter makes for some beautiful poly-pads and chordstabs.

    Im planning to do a kind of chordgenerator-module with voltage control over rootnote and type of chord(maj, min, min7, etc.), maybe inversions too. I guess it would be possible to use A0-A4 as cv-inputs, since it wouldn’t use the keyscanning anyways.

    Unfortunately im pretty new to Arduino and the code is way over my head right, so i guess i will use a second Arduino to read the cv-inputs and send the correct Midinotes to the nano-solina and see how that works out. 🙂


    • janostman Says:

      I’m kind of proud of it myself.

      • Robin Says:

        I just noticed a little quirk when using it with a midikeyboard, for example: when you play a four-note chord and let go of three notes, the whole chord will go on until you let go of the last note.. maybe there is something wrong with my midikeyboard? has anybody experienced the same issue?

      • janostman Says:

        It’s not a quirk. It’s Paraphonic and not Polyphonic.

  13. dark music blog Says:

    i like your work. thanks for sharing.

  14. Gary Says:

    Thanks so much for sharing! Here’s my version;

  15. Günther Klebinger Says:

    Awesome project, I really can’t wait for the christmas holidays to build my own!
    Do you have a bigger Version of the schematics somewhere? The picture ist quite small… Thanks!!!

  16. gartenxxl Says:

    With hаvin so much content and articles do you ever run into any
    issues of plagorism or copyright infringement? My site has a lot of
    exclusive cⲟntent I’ve either created myself or outsourced ƅut it lookѕ like
    a lot of it is popping it up alⅼ over the web without my peгmission. Do you know any ways to help reduce content from ƅeing ripрᥱd off?
    I’d defіnitely appreciate it.

    • janostman Says:

      I don’t think there is a way to stop plagorism.

      I choose to only post things I don’t mind being copied.

  17. Norduk Jo Says:

    My best congrats for your blog and projects. You are a genius!
    I’m trying to make this magnificient synth. (I haven’t slept for days, try help with another cool person, but now… you are my only hope).
    I’m using an arduino MEGA ADK. Put the 8 col and 5 rows in the respective pins in the code. I had to adapt the code to read fast and recognize the pins in MEGA. (When finished and working proper, I will give you the code so may others get the way). I’m using a cheap toy keyboard (20$, not so cheap), but with the same col and rows.
    But…. In the physical octave, when I play for example G, Is the same note in the other octaves. Sometimes is not. the notes are little bit random after playing a while. And when i press the same key continously, it start given the same note, but after the 5th time I press, it pitch up giving another note and behaving randomly.
    Anyone had the same problem? Anyone can have an idea about what it is? Should I put all my hardware in the junkyard?
    I put the order of the wires, from backward, and foward of the col and rows, change the wires, went to a priest, an exorcist, I tried so many things, but the problem still. I’m using MEGA Adk, because I had it already and try to save good money 😦
    Aside this, I’m put succefully some features, like LCD screen, switchs for some effects.
    Any word, is appreciate 🙂
    Thank you so much

    • janostman Says:

      The problem is that your cheap toy keyboard doesnt have a diode on every key.

      It will still work fine as you discoverd until you press 3 keys at the same time and run into something called Ghost keys.

      The answer is simple, you cant fix it. Without the diodes you can only play 2 keys at a time.

      Real musical keyboards have the diodes built in.

  18. Build Your Own String Synthesizer With An Arduino – Synthtopia Says:

    […] Instructions and the full source code for the project are available at Ostman’s site. […]

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