Following this question, I acquired a second hand Behringer U-Phoria UMC404HD audio interface.

I'm suprised to find out that it seems to totally distort, or apply filter to my audio input. To better explain the distortion, I shot a little demo video, with the same audio, first passing directly to my recorder, then passing through the Behringer device: https://drive.google.com/file/d/1gkcfXRrsWcWwwyoDWwsJYNY90_eDxP8a/view?usp=sharing

PS1: I've tried all 4 inputs, different cables, different jack adaptors. I've tried output to headphones, main output and USB to my laptop. I've tried all knobs and switches. The audio is always bad.
PS2: The song is Tangerine by Glass Animals

  • Looks like you're feeding some king of headphone/mic combo output to a single mono input. i can't figure why you'd even want to feed a computer out to a preamp that way, even if cabled correctly. Why no use the pre as it's designed & use its actual outputs? From your earlier question… "I'm looking for a simple USB interface that would provide multiple 3.5mm jack audio inputs to my computer." …but that's not what you've done.
    – Tetsujin
    Jan 30, 2021 at 16:48
  • BTW, I hear no distortion, just simple phase cancellation, which has the effect of removing the centre of the image & anything placed there, like the drum track.
    – Tetsujin
    Jan 30, 2021 at 16:56
  • The configuration I set in the video is just for the demo, I have no interest using my computer as audio source. What I want is plug multiple pocket operator units and record them in my sequencer via USB. That works but the audio is awful...
    – J4kim
    Jan 30, 2021 at 16:58
  • Okay, is that normal that the interface applies that kind of filter ? I just want raw input...
    – J4kim
    Jan 30, 2021 at 16:59
  • It's not applying any kind of "filter" you've stuffed a stereo jack into a mono input & it's shorting out. That's really not the way to route it at all. Read the manual - if you want to route the outputs, use the outputs, not the inputs. I can't see from your video what it is you're trying to do at all… compy stereo out to mono in, then a headphone out to what looks like a Zoom, then out again to speakers!?! That makes zero sense.
    – Tetsujin
    Jan 30, 2021 at 17:07

1 Answer 1


Thanks to Tetsujin, I have the answer to my question: There is nothing wrong with my audio interface. I just had an inapporiate use of it.

The issue was caused by the audio source being stereo coming into a mono input.

For what I understood (but I sure am no expert), the input connector beeing a XLR/jack combo, is balanced. So it excpects the right signal from the cable to be the inverse of the left signal. As I enter stereo with similar L and R, the result was sort of a cancelation of the signal.
Edit: by left and right I mean "tip" and "ring" of the connector, which are used as positive and negative polarity for balanced mono signal (ref).

The next step for me is finding some kind of stereo to mono splitters in order to plug my Pocket Operators properly.

  • To be very clear. The XLR cable as well as the 1/4 inch jack receives one mono signal. A stereo output is two mono channels so cannot come in through one XLR or one jack. (Note: the specific interface the user is talking about, we know that a 1/4 inch jack can be used for stereo, eg as headphone).
    – ghellquist
    Jan 31, 2021 at 7:35
  • Thanks @ghellquist. Sorry I don't have the correct vocabulary, I editet my answer. There is no left and right signals but one signal being splitted into positive and negative polarity.
    – J4kim
    Jan 31, 2021 at 15:31

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