This unit takes various CVs (control voltages) and Trigger signals and controls various functions of a TC Electronics DittoX4 looper pedal. The purpose of this unit is to allow standard modular synthesizer controls to affect the various modes of the looper which is part of my matrix mixer based effects chain.
The unit's hardware is relatively generic in its construction. There's an Arduino Pro Mini at the heart of the unit. It has four trigger inputs, four control voltage inputs, two control voltage outputs and four trigger outputs. It contains a previously design PCB from my TMNSD project which hosts the trigger inputs and the cv outputs and I created a daughter card which mounts to this board to give me the trigger outputs and CV inputs.
The trigger inputs are protected from overvoltage as are the control voltage inputs. The control voltage inputs are configured to take LFO voltage ranges of -5v to +5v. The trigger inputs will trigger at 3v. These are all hardware adaptable.
|The front of the unit showing the 3.5mm sockets
The CV OUTs and the TRIG OUTs have no purpose in controlling the DittoX4 as this is controlled via MIDI CCs but it made sense to take advantage of a unit which could also provide for extra MIDI to CV abilities within my setup. This says that there is also a MIDI INPUT on the unit as well as a MIDI OUTPUT which controls the DittoX4.
I have modified the DittoX4 to only have the loop audio coming out of the unit without the input being echoed. For some information the DittoX4 is a dual looper with loop based effects ie: reverse loop, half and double speed. There was no facility to do this without hardware modification.
What I am actually controlling on the DittoX4 is the play, record of the two loopers. There are four "effects" that I also control. The effects affect both loops at the same time and can be used together. These include Reverse, which will reverse the direction of the loop playback, HOLD, which repeats a small section of the loop, HALF and DOUBLE which playback the loops at half and double speed and finally the DECAY which will fade out the loops.
Here are the functions that the DittoX4 will do based on various Trigger and CV combinations:-
- Trigger a Loop - this uses Trigger Input A and CV input A to start/dub/rec a loop - the CV chooses the loop and the trigger activates
- Stop a Loop - Trigger Input B and CV input A - stops a loop playing - CV chooses the loop and the trigger activates
- Turn on the HOLD effect - Trigger Input C - this turns on the effect number 7, HOLD.
- Control SPEED effects - Trigger Input D and CV Input C - turns one of two effects on or off - these are DOUBLE and HALF SPEED
- Turn on the REVERSE effect - CV Input B - turns on the effect when the CV input is high
- Sets the loop DECAY level - sets the value of the DECAY based on the input voltage of CV Input D
In practice the setup is quite random which was always the purpose. One of the nice effects to changing the loop direction with the reverse effect which can slow progress the loops position. Manually recording the loops seems to be a better approach but due to the nature of how the pedal works, this isn't simple. The MIDI CCs emulate the buttons on the pedal mostly. So for example if Loop 1 has no loop in it then the CC code will put it in record and another press will send it into play mode. A further press, the same CC, will overdub the loop. Of course I would have preferred more accurate controls but I had to live with what I had.
|Rear view of case showing power connection and MIDI - Someone's feet and tail in the background
I'm quite proud of the small wood and acrylic case I made for the unit and I am surprise I fitted all the electronics inside. This was made with help from my CNC router. There are way too many wires. If I were to do this again I would avoid wires altogether and make up a PCB which would attach to the front panel 3.5mm sockets. The unit is powered from a 12v DC plug pack which is converted to a dual 9v using a buck converter.