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Using Griffin Powermate as a scratch controller



  • I am looking for a simple way to use a rotary encoder to scratch thru a looping audio file. I have a Powermate and a Shuttle contour in hands, but both are only emulating clics or mouse movements, resulting in shattered audio playouts. I need a nice and clean output as if I were rotating a turntable by hand, both directions. Does anybody succeeded in such a project ? Or do I have to look to DJ turntable interfaces as Numark or Pioneer ? Anybody had success with this kind of device interfaced with Izzy ?

    Thanks,
    Marc


  • You can use arduino and a rotary encoder if you want a clean interface. I also have a novation nocturn, this has rotary encoders that can be reconfigured as continuous.


  • Tech Staff

    I have a power-mate and it's pretty cool - but a bit awkward to interpret the MIDI messages. I need to look at it again to see what is possible.



  • I used a DJ Hero Controller + Arduino. Cheap and cheerful.



  • hi marc,

    i would try to convert the sound into a movie and fiddle around with the speed setting
    this shall give you a much smoother playback then selecting the position
    interfacing the devices is the second step
    i could imagine a counter in a short timer
    count modifications(rotation of your knob) modify this to speed
    reset speed after xxx seconds
    good luck
    best clemens


  • Thanks for all your suggestions. The thing will be buried deep into a museum exhibit, so no need to have a nice and neat look. The speed control of a movie seems to be the best option for smooth playback. I haven't set any hardware yet to make some tests, but I will very soon. As the installation must last about 6 month unmanned, it has to be as simple and sturdy as possible, with no manual config to do on daily startup.



  • Just thought: Using a DC motor to generate voltage proportional to the rotation speed, and turn it to data to be read by Izzy. I just need something to catch direction of rotation, or offset the output voltage with a bunch of transistors.


  • Tech Staff

    Had a little test... c42e6f-screen-shot-2014-07-22-at-12.32.57.png edad00-power-mate.izz





  • sculptures test motivated me to try how the speed approach could sound like

    so here it is
    without the power mate aded two buttons for left and right turn
    and a toogle to switch between the position and speed way

    b0f295-power-mate_2.izz



  • I think I will forget the Powermate approach, mainly for mechanical reasons. I need a really sturdy and reliable setup.

    I've made some tests with an Arduino sending me MIDI pitch messages according to the speed of a DC motor and two different velocity according to the direction (actually, I simulate it with a pot and a toggle switch). Hardware side is fine and everything is OK when playing forward, from 0 to around 300% which is the max speed I want to achieve. But backward play out has hiccups. So I created a backward file which I sync to the other file and switch from one to the other according to the direction. But sending direct position makes my ears bleed ! 
    So I've added a lookup when direction is changed and feed the actual position to the muted player only at this time. 
    It works fine but as I am quite a rookie with Izzy, advises for better programming are welcome !

    b21488-ko-scratch.izz