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Thread: Multiple module synthetyzer system

  1. #1

    Multiple module synthetyzer system

    Hi!

    I've always wanted to have a rack of modular synths, but here in my country is really hard to import things that expensive (the taxes are too high).
    So, as an alternative I started working with Teensy, and thinking on building all the ones that I want by myself. I've recently finished the first one, which is a simplified version of the 4MS Ensemble Oscillator, and it sounds really good.

    The next step will be to make a clock and a sqeuencer (with another teensy board), with outputs to trigger the oscillator i built, and a drum machine in the future.

    I'm not sure yet how I will make the communication between the modules. I know I want to use patch cords (3.5mm) and mono input jacks. I guess I will add one more multiplexer and an analog pin if its a voltage signal, or the audio input of the audio shield if its a sound signal.


    I found the PolyMod project, which is a modular synth with a Teensy (https://www.pjrc.com/polymod-polypho...-modular-synth), I looked into his GitHub and I think he "programmed" the patch connections to be made dinamically between the objects, and they don't actually send information. I want to do something like that, but with separate teensys (one for each module), and with real voltage traveling through the cords.

    I just wanted to know if anybody tried doing something like this, and if you think in any problems I can encounter. I'm a software developer, but just starting with electronics.

    Thank you for reading

  2. #2
    Hi,
    I also wanted a rack of modular synths, but as you found that it was too expensive.
    When starting to produce my own modules I first tried to make my modules communicate via controlled voltage but found it too hard to design with limited knowledge of electronics design.
    Then there are loads of different controlled voltage "standards" out there to consider, -5V/+5V,-8V/+8V,0V-2.5V, 0V-5V,-10V/+10V..
    So I decided to make my modules communicate via four of the serial ports of the Teensy 3.5/4.1 and named the project "NUCLEUS Digital Modular Synthesis"

    CorteX is a simple 14-bit asynchronous serial communication protocol that I wrote for the project. It sends values between 0 and 16383 at 500kb/s to and from modules.

    Each of the Nucleus modules has:
    Four data input/outputs.
    Four gate input/outputs.
    Two audio in/out channels.
    A 2.2 TFT screen.
    Two rotary encoders, one for parameter and one for values.
    Four potentiometers for real-time parameter control.
    The size is 26 HP.


    I have made a small webpage here: https://johanbilen.wixsite.com/nucleus/
    A video of Nucleus in action: https://www.youtube.com/watch?v=a935eS4JhG4

    One downside with my DIY approach is that my system can't communicate with Eurorack CV modules.
    A positive is that since its software based and not a fixed hardware design I can improve upon my modules and add functions etc.

    /Johan

  3. #3
    Thats what i want to do! I feel better now that I know it can be done. Congratulations on your project, it looks and sounds amazing!

    I don't want mine to be compatible with Eurorack, it will be all teensy.

    Im trying now to connect the analog outputs of one teensy to a digital pin in another one, reading the PWM length, and I think its pretty accurate. Why did you prefer the Serial pins?

    Im working on the sequencer now, when i have it working I will upload a video with it trigering the drum machine

  4. #4
    Hi, I needed higher resolution than 8-bit to avoid stepping of the filter and oscillator frequencies, and also the possibility of sending four channels of data in parallel, so I choose hardware serials of which there are 6 on the T3.5 and 8(!) on the T4.1. There are only 2 DACs on the T3.5 and none on the T4.1.

  5. #5
    I read the PWM signal with a digital pin (digitalRead) and wait for the rising edge
    Im using this class: https://github.com/xkam1x/Arduino-PWM-Reader and the result is always between 0 and 222 (idk why it does not reach 255)

    I don't know how Serial works but Ill look into them.

    Thank you for your comments, its really helpful

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