A client was having a problem recording his Behringer Odyssey synth into Cubase. The Odyssey was connected to his Focusrite Scarlett 18i20 but only very faint sound could be heard on the input channel.

I asked my client to run a few tests. First we checked that the synth was definitely powering on and generating sound. We plugged a pair of headphones into the synth and my client reported that he could hear the notes being played back loud and clear when he pressed the keys. This told us that the synth was working correctly.

Next we checked the input of the audio interface by connecting a different synth to the Scarlett 18i20. We could hear the other synth fine. This confirmed that the Focusrite input and the cable were working.

Behringer Odyssey cable jack

I asked my client to check the cable and we noticed it was a TRS (Tip Ring Sleeve) type jack plug. Also known as a stereo or balanced jack. Checked the manual for the Odyssey and confirmed this was the problem. The Odyssey is designed to use a TS (Tip Ring) type jack plug. Also known as a mono or unbalanced jack.

By running an unbalanced signal via a balanced cable into a balanced input we were cancelling out the sound of the synth via phase reversing two signals. 

More info about Balanced and Unbalanced audio here:

What’s the Difference Between Balanced and Unbalanced?

I showed my client the right cable to order from Amazon. We connected again a few days later and he confirmed the synth was now playing back fine and able to be recorded in Cubase.