Behringer UMC 202HD for measurements

Nice work, Jesper! So, the hardware is pretty much done I assume. While the basic noise floor is just a bit higher, the harmonics are all lower. Could we blame it to the extra gain of the ABM? Do you recall if the pot of the Behringer's modified input -the back panel control- was at the same level for all measurements? Also, when time allows, could you repeat the first measurement with inputs floating?
 
Thanks for the reply's.

I allways forget to write the setup conditions, sry... 🤔

The input attenuator on the Behringer is not touched, allways at it's MAX (all the way to the right for minimum resistance)
Input's are floating as you explained me post https://www.diyaudio.com/community/threads/behringer-umc-202hd-for-measurements.341309/post-7502670
I did check my cables one's more and took some new fresh shoot's, with a bit more explanation.

I also attached the Outputcard schematic here.

You are absolutely right, that the output card is adding just a tiny bit of noise.

RED = Directly to Behringer, Green, Blue and Orange through SuperRanger.
DiffeFLOAT.png


FLOATING input -0dB 1kHz Gain x1.3.png


FLOATING input -6dB 1kHz Gain x1.3.png



OutputCard Schm.png
 
This is not exactly related to this discussion, but I thought that this would be the best place to ask, with so many knowledgeable people.

About the behringer UMC202HD. I need to know what is the component marked D2 on the board and the specs so I can look for a replacement. It looks like some sort of diode and it has the marking P5 on it. (See circled component on pic below). It's on the tracks of the USB data(+) and (-) input from the cable before they both go on to reach the XMOS chip.

I'm asking this because someone handed me a UMC202HD that's busted. To make a long story short, the solder of the USB-B female port eventually broke after years of plugging it in and out. The former owner decided to remove it altogether and wanted to make the USB cable connect directly onto the board. Unfortunately, as he tried to do so, he ended up damaging the component that's marked D2, right behind the USB-B connector.

I'm no expert and I don't have a lot of knowledge regarding components but I've had some success in repairing parts of circuit boards in the past.

I told him I'd give it a try, but I just need a replacement for that tiny part.

Thanks for your help!

20240401_000008.jpg
 
It is a double diode for electrostatic discharge protection -ESD. Supposedly, the Xmos microcontroller has one built-in. The soundcard should work without it but it's an additional safety measure. I don't know the exact part but search for TVS diode for high speed usb in SOT323 package.