Control Voltage for the Monotribe – Part 1: Making an Adapter Cable

I always used MIDI. I am very familiar to MIDI: from the communication between Pure Data and my software synths, to my PCR-500, when using the Volcas or the Microkorg… So I never understood all the fuzz about Control Voltage (CV)… for me it looked like a relique from ancient times. I even brought the DinTribe adapter to hookup my Monotribe to my other synths and controllers.

When the 2.1 firmware update for the Monotribe was release, it added CV-Gate input connectivity. Since now I am the proud owner of a MicroBrute and a SQ-1, I decided to give it a go. This is how I made the cable adapter for the Monotribe, how I calibrated it and also some ideas I had during my experimentation. This text is accompanied by YouTube videos showing the steps I took.

Although the firmware update adds CV/Gate connectivity, it does not physically adds new ports on the back of your Monotribe. The Monotribe can accept CV/Gate coming into its Sync In port on the back. But CV and Gate are two signals, so to get them into a single port means you must have different channels going on. Moreover, the Monotribe need these signals to be feed using a TRRS jack, and not your regular stereo jack (See Figure 1). On the other hand, most synths and sequencers (including the MicroBrute and the SQ-1) offer distinct sockets for CV and GATE outputs.

Figure 1: How to connect the Monotribe via CV/Gate. Notice the order of the Gate, CV and Ground (GND) on the TRRS jack.
Figure 1: How to connect the Monotribe via CV/Gate. Notice the order of the Gate, CV and Ground (GND) on the TRRS jack.

In order to connect both equipments, I brought a small Y-Cable adapter from Amazon which is used to connect speakers and microphones to laptop PCs, tablets and cell phones. The cable also came with an additional adapter that swaps the lower Ring (Ring 2) with the Sleeve: apparently, there are two configurations for the headphone/mic combo port on the market.

I used a multimeter (on continuity or resistivity mode) and one of the mini-patch cables of the MicroBrute to text which of the sockets connected with which of the TIP or RINGS in the jack of the cable. This is more-or-less shown in the video, but I can assure you it was easier to do the first time around, without having the camera and the tripod between my legs. In the case of the cable I had, I needed to place the adapter so that the tip of the CV socket would connect to the RING 2 of the jack which was going inside the Monotribe. I also wrote two litte pieces of paper with the words CV and GATE, and wrapped them around the corresponding socket on the cable with adhesive tape… just to be safe and know which is each.

Now I can connect the Monotribe to the Microbrute and use the latter as a keyboard for my very first hardware analogue synth. But you still need to configure and calibrate the Monotribe.