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MERIS MIDI box, DIY version

MERIS produces incredible pedals for guitars (but not only). They really sound great. In my opinion, they are the holy grail of any sound seeker/modeler. I am a very happy owner of their guitar synth pedal named ENZO.

I really wanted to control my Enzo pedal using my main MIDI controller : the Behringer FCB1010. For this, I needed a MIDI Box to convert a 5-pin MIDI plug into a MIDI jack. Indeed, all Meris pedals are equipped with a TRS jack to use either a MIDI box or an expression pedal.

On their online shop, Meris are selling their MIDI I/O 89$ : way too much in my humble opinion... I decided to create my own DIY MIDI box.

First of all, here is how the MIDI jack is used by any Meris pedal:

Based on this, I created a MIDI interface with diagrams found on the Internet. Three main parts:
  1. The voltage regulator based on LM7805
  2. The MIDI in buffered by an optocoupler 6N138
  3. The MIDI out

To make things faster (and better done...), I purchased a MIDI shield for Arduino plates where the MIDI in and out are already done. It costs around 3$ on every online store. Only the voltage regulator is missing.

Adding a aluminium housing, all parts cost less than 12$. It was worth the try ! And moreover it works well !
Here is a picture of the final result

Now that I can control my Enzo pedal over MIDI, here is the MIDI CC table used by Meris :



  1. Hi. Do you have some picture of your interface? I can read some schematics but I don't understand if your can connect multiple pedals

    1. Hi,
      Thank you for your comment.
      Unfortunately, the interface is now in its box and fully integrated in my rack. I don't have any picture of it.
      I relied on the MIDI shield for Arduino to make it work.
      As I only possess one MERIS pedal, I didn't explore the possibility to control multiple pedals. I guess it might be possible but it will require to send messages over multiple MIDI channels.
      Good luck for your project - JC

    2. Hi, I have updated my article with a recent picture of the circuit that I made. As you can see, very simple.
      The 9V power supply goes into a 5V voltage regulator (with some capacitors, as adviced), which powers the MIDI shield plate for Arduino.

      I followed the line to solder the TRS jack to ground-MIDI out - MIDI in.

      I just had to be careful as I use an aluminium case : this can cause shortcuts. I glued some paper on the case to avoid that.
      I hope this helps - JC

  2. Hey, thanks for a very helpful article. I have a question about MIdi Out and Mid Thru. Have you utilized those? Will they work at all? Thanks

    1. Hey!
      Yes, I use the MIDI OUT to get messages from my MERIS pedal.
      For now, I don't use the MIDI thru.
      However, I will use it in the future as a new MIDI device will be mounted on a pedal of my rack.

    2. Oh wow! Thank you for such a quick response ) But do you really need a Midi Thru out? According to the MIDI i/o box manual you can configure if Midi Out will work as Out or a Thru? Or you mean to use Midi Thru when Midi Out is used as an out? Thanks again.

    3. Yes: my setup will be MIDI OUT used as an out, and MIDI THRU forwarding messages to the upcoming device


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