Otto connected to soundcard

WARNING! Make sure your soundcard can handle the hot output levels from your eurorack synthesizer system before you make any connections.

In this article we show how to solder a 8 channel audio cable and attach it to the Otto Passive.

This is only for inspiration. In your case you may have other connectors, another number of connectors or a different need than to connect the soundcard.

Building instructions

  • Use a shielded mono cable and cut it into 8 peaces with the same length.
  • Remove the isolation on both sides of each cable.
  • Solder the plugs/connectors on one side of all 8 cables (picture 1).
  • Use a female header with 16 positions and bend out every other solder pad (picture 2).
  • Solder all the 8 cables to this female header. The first pin is jack 1 signal and the second is GND. The third pin is jack 2 signal and the fourth is GND. And so on… (picture 3).
  • Make sure not to make any shorts! Use a multimeter for testing!
  • Mount the Otto 8 Passive in your rack.
  • Connect the header to the top 16 pins on the backside of the Otto 8 Passive.
  • Connect the 8 connectors to your soundcard. In this example we have connected all 8 cables to 8 inputs of a multichannel soundcard (picture 5).
  • We have cut out the word “IN” from a sticker and put at the top of the front panel.
  • Now it’s really easy to connect your soundsources to your soundcard.
  • 1. Solder plugs to all cables
  • 2. Bend every other leg on the 16 position female header
  • 3. solder signals and grounds to the female header
  • 4. The ready made 8 channel cable
  • 5. Connected to the soundcard
Easy access from the rack

Now you have easy access from your eurorack to all 8 inputs on your soundcard.

In the picture above you will also see another Otto 8 Passive with the label “MIX”. That module has the Single-Op KIT addon where you can create a 6 channel mixer. See here for more information.

On the backside we have connected the break-signal from the output+ (pin 31) on the “MIX”-module to the break-signal on the “IN”-module for jack 1 (pin 17). We have used a female to female dupont cable. A second dupont-cable for GND from pin 32 on the “MIX”-module to pin 18 on the “IN”-module.

With this arrangement, we now have a simple 6-channel mixer normalized to input 1 on the soundcard. If we insert a plug into jack 1 on the “IN”-module we override this normalization and connect that signal directly to input 1 on the soundcard. If we insert a plug to the output+ jack on the “MIX”-module, we also break the normalization but now we tap the mixer output to our inserted cable instead.

You can expand this thinking with more mixers if you want.