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Thread: MIDI clock compatibility device for analog delay unit

  1. #1

    MIDI clock compatibility device for analog delay unit

    I want to be able to take the midi clock signal from my loop pedals (EHX 95000 & Ditto X4) and use it to set the tempo of an Ibanez Echo Shifter ES2.

    The Echo Shifter ES2 Delay uses an analog delay but it also has a "tap tempo" footswitch (not analog but whatever)

    I want to make a Teensy read the MIDI from the loop pedal, and when it detects a clock tempo signal I want it to close a circuit temporarily (the poles of the momentary tap tempo footswitch) thereby syncing the tempo of the analog delay and the MIDI-compatible loop pedals.

    The idea is that Once the MIDI signal says "there is a beat NOW" the Teensy will send a voltage across a couple of different pins, and this change in voltage can be used to trigger a simple secondary circuit that will CLOSE a couple of contacts (the tap tempo), but will keep this signal seperate from the teensy to avoid inteference.

    Personally I think it is feasible. My coding ability is very low, but I have successfully completed a Teensy MIDI controller project already. My other audio tech skills are higher.

  2. #2
    Member garcho's Avatar
    Join Date
    May 2020
    Richmond, VA
    I'm going to paraphrase to see if I understand you correctly:

    You want the 95000 and Ditto to set the tempo of the ES2 via tap tempo. Tap tempo is just a momentary switch closing to ground (usually), so you want the Teensy to "close" the switch, instead of your foot, to synchronize the 3 effects.

    That's very easy to do. MIDI clock is 24 pulses per quarter note, so if you divide by 24, you get 1 "beat". Every time the Teensy receives the 24th MIDI clock command (0xF8), it brings a pin from high to low, simulating a momentary switch closing to ground.

    but will keep this signal seperate from the teensy to avoid inteference.
    I don't understand what you mean by that.

  3. #3
    Junior Member
    Join Date
    Aug 2018
    Quote Originally Posted by Baritone_Frank View Post
    but will keep this signal seperate from the teensy to avoid inteference.
    My assumption is that the OP would like the switching signal to be isolated from the Teensy itself to avoid any noise from the Teensy making it's way to the pedals.

    I'm no electrical engineer or expert, but an opto-isolated circuit should be pretty easy to build to do this. A relay could be used as well but seems a bit bulky and slow for what an opto-isolator should be able to do by itself. Although remember that opto-isolators (I am pretty certain...) reverse the logic; so a 1 from Teensy will be an output of 0 from the opto-isolator. (Someone please correct me if I am wrong on that....)

  4. #4
    I currently have not tested the ES2 because It's been bought but yet to be delivered. It is powered by 9vDC. I was concerned the voltage might be too high to connect directly to the pins on a Teensy 2.0 without damaging the board. Obvs I will be testing the vltage across the momentary switch in due course.

    There could also be noise/interference which would be exacerbated by the gain stages of the amplification circuit.

    Many thanks for your helpful insights so far.

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