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Quick measurements of Behringer UMC22

scott wurcer

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Now you're making me look like I'm drunk-posting. :D

Sorry about that I had hoped it went unseen. I'm used to doing it with synchronized clocks and averaging short records. I realized that taking a 1M FFT could represent 10sec of clock drift.
 
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pkane

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Clock looks to be a long way out. REW can measure the clock error if a timing reference is used and the associated Analysis options are selected.

That’s what I thought when I saw the phase plot. I’ll need to do a little more testing, but have to assume the clock on UMC22 is running too fast or too slow compared to Apogee Element24.
 

LTig

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Because the generated tones are all periodic within the FFT length.
Correct, but this implies that the clocks of DAC and ADC are synced. This is not the case here, and it's probably only the case if input and output are located within the same soundcard.

I'd say you can use a rectangular window for measuring analog electronics, using a soundcard with ADC and DAC. If you use different soundcards for input and output (as you must if you want to measure a DAC or an ADC outside of a simple loop back) you must use another window. I use hanning in REW.
 

Blumlein 88

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Deltawave should let you see relative clock rates Paul. :)

Or the manual way is to feed a quarter sample rate tone and record it. Easy to get close graphically. Here I used a 11.025 khz tone at 44.1 khz sample rate. Highlight between two troughs. In this case that is 11,132 samples. Take the reciprocal of the samples between troughs and you'll know the speed difference. In this case about 90 ppm. I know I'm telling you nothing you don't already know. Just a reminder I guess.

1573677015067.png
 
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scott wurcer

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Correct, but this implies that the clocks of DAC and ADC are synced. This is not the case here, and it's probably only the case if input and output are located within the same soundcard.

OTOH we ran some tests using a miniDSP doing digital RIAA from a multi-tone with inverse RIAA playing off of a Teac DR-60D field recorder and it was much better than this. Just lucky I guess.
 
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pkane

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Deltawave should let you see relative clock rates Paul. :)

Or the manual way is to feed a quarter sample rate tone and record it. Easy to get close graphically. Here I used a 11.025 khz tone at 44.1 khz sample rate. Highlight between two troughs. In this case that is 11,132 samples. Take the reciprocal of the samples between troughs and you'll know the speed difference. In this case about 90 ppm. I know I'm telling you nothing you don't already know. Just a reminder I guess.

View attachment 38711

Thanks, Dennis, I’ll have to give DW a try ;)
 
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pkane

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REW switches the window to Rectangular automatically when doing multi-tone. I can try forcing it to use something else :)

Rectangular window was the culprit in the strange looking multi-tone test. Here's the DAC multi-tone capture, using a different window:
multi-tone-DAC2.png


And the same for the ADC:

multi-tone2.png
 
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pkane

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And now, since @Blumlein 88 reminded me that I can actually use DeltaWave to do some measurements :) here are some:

Below is the comparison of the original digital file matched by DW to the one recorded using UMC22 as ADC and Element24 as the DAC.

RMS null is -61dB, correlated null depth is 63dB. Clock drift appears to be around 57ppm, that's the cause of the strange looking phase plot.
1573694237625.png


Phase error calculated and corrected for by DW (blue is the original phase error, white is after the correction):
1573694452382.png
 

JohnPM

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Correct, but this implies that the clocks of DAC and ADC are synced.
The rectangular window is applied if the Distortion button has been pressed to calculate TD+N and SNR figures, which are generated per the AES17 synchronous multitone analysis spec. That does, of course, require output and input clocks to be either the same or very close, as explained in the help.
 

Duckeenie

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I bought one of these a couple of years ago to do room measurements. Comparing it to my DAC I noticed it has an obvious flabbiness around the bass frequencies, it's so obvious that I wonder whether it's a defective unit or just par for the course at this ridiculously low price. Anything in the measurements that suggest why it would sound so broken in the lower frequencies?
 

Jimster480

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I bought one of these a couple of years ago to do room measurements. Comparing it to my DAC I noticed it has an obvious flabbiness around the bass frequencies, it's so obvious that I wonder whether it's a defective unit or just par for the course at this ridiculously low price. Anything in the measurements that suggest why it would sound so broken in the lower frequencies?
Are you using it to directly power your headphones? Or are you feeding the output into an Amp?
 

Duckeenie

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Are you using it to directly power your headphones? Or are you feeding the output into an Amp?

It's feeding into an amp. It exhibits the same behaviour whether or not I use balanced or RCA cables.
 

Jimster480

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It's feeding into an amp. It exhibits the same behaviour whether or not I use balanced or RCA cables.
I've only used my 202HD into my A30 like once or twice... I only use it for recording so I'm not sure. I could make a point to test it for you if its important.
 

despearce

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Not sure if anyone can help, I've bought a umc22 and 8000 mic to take some measurements using REW. I can't get any sound from my speakers at all, setup is pc-umc22(by usb)-8000 mic(xlr) and umc22 to line input on rega elicit amp. I'm using 6.3mm stereo jack to rca from the umc22 back panel.

I've installed REW and asio4all driver and gone into preferences on REW and opened the asio4all app. Only options are Realtek soundcard, a USB output or virtual output, none give me any output from the speakers. Any ideas of where to look or what to do?
 

AnalogSteph

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I'm using 6.3mm stereo jack to rca from the umc22 back panel.
That should be 2 pcs. 6.3 mm mono to RCA. You should have output anyway, just left channel only. Try the headphone out and make sure to turn up the output on the UMC22. Also try Java audio instead of ASIO in REW, it's not like a PCM2902 can do more than 16 bit anyway.
 

girtab

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So would this interface be recommended for listening to studio monitors or are there any (audible) imperfections
 

maverickronin

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So would this interface be recommended for listening to studio monitors or are there any (audible) imperfections

It will work just fine for that, especially if you're on a budget or specifically need a UAC1 device for an old PC or a game console.

You might get a bit of extra hiss if your monitors are alread dead quiet, but that's the only likely audible defect.
 

AnalogSteph

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Not sure the UMC22 is worth it if you just need it for the output. The thing is literally worse than (decently implemented) PC onboard audio. I would rather come up with a custom balanced adapter cable or include a Behringer HD400 for galvanic isolation (cables: 3.5 mm --> dual 1/4" TS, 2x 1/4" TRS ---> XLR male). It takes very little to turn an unbalanced output into a balanced one - it's the balanced input side that does the heavy lifting.

The charm of an interface like the UMC22 is having a complete recording package with a decent headphone input at a low price. It can accommodate a dynamic or condenser / phantom powered microphone, a guitar, a set of monitors and headphones just about well enough to be usable. If you don't actually need a majority of this I/O, I would suggest also looking at other options.
 

bennetng

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Rectangular window was the culprit in the strange looking multi-tone test. Here's the DAC multi-tone capture, using a different window:
View attachment 38754

And the same for the ADC:

View attachment 38755
I tried to use the same settings as yours and here are what I got for the Realtek ALC897 loopback on a $80 motherboard in my self-built cheapo PC. Using shared mode with edechamps' limiter hack.
48thd.png

48multi.png

48fr.png


Can't say the Dell was not affected by some preinstalled crapware or silly drivers.
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