Hohner Rhythm 80 Midi with uniPulse

This manual describes how to use and install the uniPulse midi interface in a Hohner Rhythm 80 drum machine.

Installation requires soldering some wires and drilling holes for the midi socket. However no need to cut any traces.

midi socket installed in a rhthm 80

Picture by Beatkamp

After installation you will be able to trigger all sounds via midi, most velocity sensitive.

Bass Drum
Low Conga
Low Bongo
High Bongo
Cow Bell


Unplug the Rhythm 80 when working on it!
After opening up the enclosure, you are presented with the following view of the boards:

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Hohner Automatic Rhythm Player Midi

This manual describes how to install our uniPulse midi retrofit in a Hohner Automatic Rhythm Player.
After installation you will be able to trigger all 10 sounds, most of them fully velocity sensitive. You will not be able to sync the internal rhythms to midi clock however.

Soldering pulse triggers

Installation is fairly simply and requires you to solder 10 wires from uniPulse to points on the Rhythm Player voice board. These are P1-10 and CV (as labelled on the back of the uniPulse board). The black P7 wire is not used.

Unplug the machine, remove the slotted screws and open it. Then solder the wires as shown in the following pictures. The “CV” connection used for the Maracas needs an additional diode. Any Diode is fine here. As you can see, the cathode of the diode (marking) connects to the cathode of the existing diode.

INstalling the midi socket

In order to install the midi socket you need to drill 3 holes. A stencil for drilling is provided. For the large hole you can use a stepping drill. Now mount the socket using the screws provided.

Mounting the unipulse board

You can mount the uniPulse board anywhere in the machine. We decided to use thick double sided tape to mount it on the rear. Make sure the board can not short to the metal chassis.

first start

After installation, plug in the machine and turn it on. The LED on the uniPulse board should light up indicating proper power connection. Using the uniPulse configurator tool, upload config file for the Hohner Rhythm Player (zipped, extract before opening in the configurator)

That’s it! have fun!

How to open unsigned app on OSX

This is how to open our Firmware updater utility on OSX. This should work with any other unsigned app as well. This has been tested with OSX Big Sur but probably works with older OSX versions as well.

Step 1:

Download the app. Safari will place it in the Dowload folder. Navigate to the Download folder in Finder.

Right click on the file and select “new Terminal at Folder”

Step 2:

A terminal window opens. Type the following command: (you can copy and paste it here)

sudo chmod -R 755 ./

You will be promted for your password. Enter your password – it will not be visible. After entering your password press enter.

Step 3:

Open the folder with the little arrow on the left, right click on the “Tubbutec Firmware Updater” application and select “Open”

You will see a message that the file can not be opened. Click Cancel.

Step 4:

Repeat step 3! The second time you click open, the following window will appear.

Click Open and the app will start 🙂