Open Source Synthesizers Hack Chat

Matt Bradshaw stops by the Hack Chat for a discussion on digital open source synthesizers

Wednesday, January 23, 2019 12:00 pm PST Local time zone:
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Matt Bradshaw will be hosting the Hack Chat on Wednesday, January 23, 2019 and noon PST.

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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 digital music
  • Where the PolyMod has gone since winning the Musical Instrument Challenge semifinals

You also might want to check out the Modular Synth Discussion, a very active chat that digs into the guts of all sorts of modular synthesizers.

  • Open-Source Synthesizers Hack Chat Transcript

    Dan Maloney01/23/2019 at 21:31 0 comments

    OK, folks, let's get started! Welcome to the first Hack Chat of 2019. Looks like we have a good turnout for Matt Bradshaw, who's here to discuss all things open-source synthesizer.

    @Matt Bradshaw, can you give us a little bit of your background?

    R joined  the room.12:07 PM

    Matt Bradshaw12:07 PM
    Sure - I have a degree in physics, but then spent quite a few years as a web developer. I've always played in bands and enjoyed music technology, so it was natural to merge my music interests with my programming interests. This led my to Arduino, Raspberry Pi, and Teensy projects, and my last few projects have all been based around Teensy audio.

    Matt Bradshaw12:08 PM
    So I now make digital musical instruments, often with the aim of using them in my band (Robot Swans).

    manualf12:09 PM

    Great, thanks. That actually ties right into the first question, from Andrew Bakhit: why did you go with a Teensy for your PolyMod project?

    Actually, the full question was: "For your PolyMod project, why the choice to use a Teensy to detect modules and cables to set module configuration? This seems it would result in less hardware but in much more coding"

    And for anyone who hasn't seen the PolyMod:

    Matt Bradshaw12:12 PM
    Well, the first version of the project used an Arduino Mega to detect the connections, and this information was then sent via serial to a PC, which was running a custom soft synth written in Javascript

    Taiwo12:12 PM

    Kevin12:12 PM
    It is a common thing to trade off between hardware and software.

    manualf12:12 PM

    Matt Bradshaw12:12 PM
    But once I realised the Teensy could actually do everything, I switched to using that, because I really liked the idea of building an instrument that didn't require a PC

    Johny Radio12:13 PM
    "detect connections"?

    Matt Bradshaw12:13 PM
    Yes, Javascript was a silly language to use, but I just happened to know quite a lot about the JS Web Audio API from my previous job, so it was the quickest way of getting it working!

    Matt Bradshaw12:13 PM
    Okay, so when I say "detect connection", here's what I mean:

    manualf12:13 PM
    I think thats cool man !

    manualf12:13 PM

    manualf12:14 PM
    and web api!

    manualf12:14 PM
    that rocks

    Matt Bradshaw12:14 PM
    In a regular analog modular synth, the audio flows from one module to another, as actual, analog audio (or control voltages). I really liked the idea of creating a signal chain in this way, but I wanted to do it virtually

    Matt Bradshaw12:15 PM
    So, I built a physical synth that looks very similar to an analog modular synth, and you still connect the modules to each other with physical cables

    Matt Bradshaw12:15 PM
    (3.5mm patch cables)

    Matt Bradshaw12:16 PM
    But instead of audio flowing down the cables, it's just a sort of matrix, where the Arduino or Teensy sends a "test voltage" to each module in turn, and then "listens" for that test voltage from each module in turn

    Ah, ok - just about to ask what's on the patch cables. That's pretty neat!

    Matt Bradshaw12:16 PM
    The end result is that the software synthesizer, whether it's in Javascript or on a Teensy or whatever, will "know" which modules are supposed to be connected to each other

    Matt Bradshaw12:17 PM
    At one point I had hoped to make the project as an interface to VCV Rack

    Matt Bradshaw12:17 PM
    (Open source modular software synth)

    Matt Bradshaw12:17 PM
    But a) I really wanted the whole instrument to exist in a single box without a PC and b) I didn't have the right skills :)

    Tomáš Mládek12:19 PM
    Interesting approach, would it be possible to make this anyhow interoperable with other synths built like this, or even with separate modules?

    Tomáš Mládek12:19 PM
    Or is the whole "patch" on principle contained within the one box / synth?

    Matt Bradshaw...

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Andrew Bakhit wrote 01/23/2019 at 18:45 point

Another question :) why the choice of making the synth similar to the eurorack modular style? It seems like the way this is made it doesn't necessarily need to be in the eurorack format but it could be the form of like a desktop synth

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Andrew Bakhit wrote 01/23/2019 at 18:28 point

For your PolyMod project, why the choice to use a Teensy to detect modules and cables to set module configuration? This seems it would result in less hardware but in much more coding

  Are you sure? yes | no

Dan Maloney wrote 01/23/2019 at 00:16 point

Don't forget to post some questions for Matt's Hack Chat tomorrow, noon Pacific.

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Richard Hogben wrote 01/08/2019 at 20:31 point


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Aleksandar Bradic wrote 01/17/2019 at 00:53 point

+1 !

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