Yes! you can finally have TRS to 5-pin MIDI so you can control your HX Stomp, Nord Keyboard, or anything else with a TRS or 5-pin MIDI connection.
Midistomp will still require USB power, but a simple USB wall wart will work fine.
USB MIDI and TRS MIDI can work concurrently and you can even send different MIDI channels from each port(USB and TRS). I am working on a more versatile profile pack where you can mix different message types, so look out for that (e.g. send PC from first switch, and CC from second switch, and note from third switch)!
Please note: This TRS layout is Tip (signal), Ring (+5v), Sleeve (Ground) and will interface with standard MIDI TRS cables. MIDI over TRS was only recently defined in the MIDI standards, and some companies do not follow the standard TRS MIDI wiring. They may swap the ring and the tip. Obviously it’s an easy change to make in this tutorial if your desired application uses that alternative, non-standard wiring!
To begin this tutorial, you will first need at least one expression port on your midistomp six. If you do not have one, you can install one (or two! – much more flexible!) with this tutorial.
Parts Needed: Wire (preferably 3 or 4 different colours)
DPDT (dual pole dual throw) Slide Switch like this or similar
x4 220 ohm resistors ( x2 are optional)
This tutorial will now continue assuming you have two TRS jacks installed.
- Remove the bottom plate of the midistomp six by unscrewing with a philips head screwdriver.
- unscrew the nuts of the 5 main footswitches (the ones with white rings)
- drop the circuit board out of the bottom of the midstomp slowly and carefully. There are a few wires attached so you will be able to flip it out of the enclosure only one way (on the long edge with the USB port). You will likely need to carefully pull the tempo/bank change LED out of it’s plastic sleeve as you disassemble. Also the momentary switch should be removed if necessary.
- Note the below photo of the resistors that need to be moved to new Teensy pins.
Method: Cut the resistor’s wire/leg closest to the teensy (see the photo below – red line indicates which side to cut.
Now solder a wire from that side of the resistor to the new teensy pin as marked. Do NOT connect to the hole in the PCB on the right side of the resistor. Those holes connect to the pin we need to use for the TRS MIDI jack.
- Alternatively, remove the two resistors completely and use new resistors which have long legs and will make the distance by themselves. Make sure to insulate the resistor’s legs with tape or heat-shrink tube if you use the resistor’s legs.
- You can now replace the PCB and switches and screw it all back together, leaving only the bottom of the midistomp uncovered.
7. You will see in the below photo how the 3 wires on each of the two TRS jacks are assigned. Some of these wires may already exist if you have TRS jacks installed already. I would suggest removing all wires from TRS jacks and starting again with these instructions to avoid confusion. The only exception would be a single expression jack – those wires are all still the same.
If all wires are removed:
– Solder two ground wires to the “sleeve” pins on the TRS jacks.
– Solder two (preferably different coloured) wires to the “ring” (middle) pins on the jacks
– Solder two (preferably red) wires to the “tip” pins on the jacks.
You should now have 3 wires on each jack.
8. Wire up the DPDT (dual pole dual throw) switch as per the diagram below. Some wires will be connected from the TRS jack
a. Connect the tip and ring wires of the TRS jack (which we soldered in the previous step) to the two central poles of the switch.
b. Solder a 220ohm resistor to each of the two pins on one side of the switch – this is required for MIDI communication.
c. Solder a coloured wire from one of the resistors to “TRS MIDI DATA – TO SWITCH” PCB hole as shown in the photgraph below (orange wire). This wire will now connect to the “tip” of the TRS jack.
d. Solder a red wire from the other resistor to the 5v, or VCC pin as show in the photograph below
e. Solder a red wire onto the switch next to the “tip” wire of the switch. Connect this new red wire to the 5v, VCC pin as shown in the photograph below
f. Connect a coloured wire from the last (6th) pin on the DPDT switch to teensy pin 12 or “EXPRESSION DATA – TO SWITCH” as seen in the photograph below (white wire).
You may be wondering about the second resistor’s hole that we vacated earlier (next to the hole now connected to the orange wire). This needs to remain unconnected/empty.
Your switch should now look something like this:
re-check the below photographs to make sure all the connections are correct
If you have soldered the switch in correctly, you can now select whether the TRS jack connects to the MIDI output wires or the Expression Data wires. Carefully push the wires down and put the switch anywhere it will fit.
Replace the cover of the midistomp and screw it in place. You have now disassembled, modified, and reassembled your midistomp.
Now load the appropriate “TRS MIDI” profile using your computer.
(These new TRS MIDI profiles are available on the file downloads page)
For information about how to choose the appropriate profile, please read the “expression pedal usage limits” section and the “TRS MIDI” sections of the User Manual (last 2 pages)