Harmonic Distortion in UMC404HD

  1. #11 by June Kim on 02-03-2018
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    Hi Michael,

    1) The mixer plays the test signal and it is routed into UMC404HD. You wanted the mixer eliminated so I did a loopback test from UMC404HD into itself. UMC404HD's output 1 is playing the test signal and it is routed to the input 1 with a TRS cable. As you can see in the attached screenshot, there is harmonic distortion.

    2) I am using the proprietary driver for UMC404HD, which is also an ASIO driver.

    - Michael Lapke wrote View Post
    Hey June,

    My apologies for not replying to this thread earlier. Honestly I'm not sure why you would be seeing this with TRS vs XLR cable, unless there was an issue with the TRS cables in question. What exactly does the Yamaha Mixer add to the equation? Is there a specific reason why you need to use it with your UMC404HD? Further is there a reason why you're using ASIO drivers instead of the recommended proprietary ones we provide here on our website?

    You could always eliminate the Mixer and try using the UMC drivers to see if it still happens. Beyond that or any of the suggestions CARE provided I'm really not sure what else to recommend for you. Please keep me posted if you are able to make any progress.
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  2. #12 by June Kim on 02-03-2018
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    and this is the spectrum analysis for the same loopback setting instead with TRS to XLR cable. That is, the output 1 of UMC404HD is connected to a TRS cable and the other end is XLR, which is connected to the input 1 XLR jack.

    As you can see, the same signal level is matched(-20dbFS) for the main test signal at 1kHz and you see much lower harmonic distortion.

    - Michael Lapke wrote View Post
    Hey June,

    My apologies for not replying to this thread earlier. Honestly I'm not sure why you would be seeing this with TRS vs XLR cable, unless there was an issue with the TRS cables in question. What exactly does the Yamaha Mixer add to the equation? Is there a specific reason why you need to use it with your UMC404HD? Further is there a reason why you're using ASIO drivers instead of the recommended proprietary ones we provide here on our website?

    You could always eliminate the Mixer and try using the UMC drivers to see if it still happens. Beyond that or any of the suggestions CARE provided I'm really not sure what else to recommend for you. Please keep me posted if you are able to make any progress.
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  3. #13 by Ken Mitchell on 02-04-2018
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    - June Kim wrote View Post
    and this is the spectrum analysis for the same loopback setting instead with TRS to XLR cable. That is, the output 1 of UMC404HD is connected to a TRS cable and the other end is XLR, which is connected to the input 1 XLR jack.

    As you can see, the same signal level is matched(-20dbFS) for the main test signal at 1kHz and you see much lower harmonic distortion.
    Hi June,

    I got the same results you did in this configuration except I used a GXJ-235 TRS-XLR adapter since I don't have a TRS-XLR cable.

    One thing I noticed of interest and that is I'm only seeing the 2nd harmonic using the TRS-TRS loopback from 404HD output to input. When using an external signal generator I see a 2nd through 5th harmonic.

    See this image: https://forum.musictri.be/attachment...1&d=1517072540

    I don't know how relevant that is but thought it was worth mentioning.

    Ken

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  4. #14 by Michael Lapke on 02-05-2018
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    - June Kim wrote View Post
    Hi Michael,

    1) The mixer plays the test signal and it is routed into UMC404HD. You wanted the mixer eliminated so I did a loopback test from UMC404HD into itself. UMC404HD's output 1 is playing the test signal and it is routed to the input 1 with a TRS cable. As you can see in the attached screenshot, there is harmonic distortion.
    Hoping you can clarify about this:

    How are you getting a test signal into the UMC404HD if you aren't using the mixer? You said you're looping the output 1 signal back into input 1, but then how are you feeding this test tone into your UMC404HD?

    Again, as I said there's not going to be a whole lot that I can suggest outside of what CARE has already told you. At this point I'm just trying to determine that specifics to what causes this for you and hope that might shed some light on how to overcome it. So far the XLR vs TRS seems to be the biggest key factor so far, but maybe there's something we're missing here.

    Last edited by Michael Lapke; 02-05-2018 at 03:56 PM.
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  5. #15 by June Kim on 03-13-2018
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    - Michael Lapke wrote View Post
    Hoping you can clarify about this:

    How are you getting a test signal into the UMC404HD if you aren't using the mixer? You said you're looping the output 1 signal back into input 1, but then how are you feeding this test tone into your UMC404HD?

    Again, as I said there's not going to be a whole lot that I can suggest outside of what CARE has already told you. At this point I'm just trying to determine that specifics to what causes this for you and hope that might shed some light on how to overcome it. So far the XLR vs TRS seems to be the biggest key factor so far, but maybe there's something we're missing here.
    It's been a while and I revisited the thread to check if there is anything new. I am sorry that I am late here.

    You asked how I fed the test tone into the UMC404HD. It's simple. I digitally generated a sine wave test tone at a specific frequency and decibel with my DAW and saved it into a WAV file. I played that WAV file from UMC404HD and recorded from input 1 at the same time. This is how usual loopback testing is done.
  6. #16 by Michael Lapke on 03-29-2018
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    - June Kim wrote View Post
    It's been a while and I revisited the thread to check if there is anything new. I am sorry that I am late here.

    You asked how I fed the test tone into the UMC404HD. It's simple. I digitally generated a sine wave test tone at a specific frequency and decibel with my DAW and saved it into a WAV file. I played that WAV file from UMC404HD and recorded from input 1 at the same time. This is how usual loopback testing is done.
    Not sure why you're experiencing that then, please contact our CARE department so that we can help you with further troubleshooting. You can reach us by phone at 702-800-8290 (US) or +44 1562 732290 (UK) or send us an email to CARECREA@music-group.com and one of our technical CARE specialists will be happy to assist you in any way they can.

    Please keep the rest of us posted on any progress you make, thanks.

    Michael Lapke
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  7. #17 by Ken Mitchell on 03-30-2018
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    - Michael Lapke wrote View Post
    Not sure why you're experiencing that then, please contact our CARE department so that we can help you with further troubleshooting. You can reach us by phone at 702-800-8290 (US) or +44 1562 732290 (UK) or send us an email to CARECREA@music-group.com and one of our technical CARE specialists will be happy to assist you in any way they can.

    Please keep the rest of us posted on any progress you make, thanks.
    Hi Michael,

    Should anyone experiencing this issue contact CARE or should we wait for June to post an update? I've reproduced the same thing that June is seeing. What do you think will be different from what June already posted in post #5?

    Thanks,
    Ken

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    If you want "Loud", then run a piece of sheet metal through a table saw. --Ivan Beaver
  8. #18 by Michael Lapke on 03-30-2018
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    - Ken Mitchell wrote View Post
    Hi Michael,

    Should anyone experiencing this issue contact CARE or should we wait for June to post an update? I've reproduced the same thing that June is seeing. What do you think will be different from what June already posted in post #5?

    Thanks,
    Ken
    I'd suggest that anyone who's experiencing this to contact them directly and see what they can do about it.

    As for the difference, perhaps something else has come to light on their end or another technical specialists will be able to suggest something that brings the cause to light. Of course the points that were brought up in post #5 probably won't be any different, but as mentioned before unless it was affecting the recorded signal then I wouldn't even bother diving any deeper into it.

    But hey... that's just me.

    Michael Lapke
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  9. #19 by Ken Mitchell on 03-30-2018
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    - Michael Lapke wrote View Post
    I'd suggest that anyone who's experiencing this to contact them directly and see what they can do about it.

    As for the difference, perhaps something else has come to light on their end or another technical specialists will be able to suggest something that brings the cause to light. Of course the points that were brought up in post #5 probably won't be any different, but as mentioned before unless it was affecting the recorded signal then I wouldn't even bother diving any deeper into it.

    But hey... that's just me.
    For me, I try to use XLR whenever possible but the workaround is just to use these adapters instead of the TRS input on the combi-jack: http://hosatech.com/product/gxj-235/

    You do need to be careful with phantom power. Make sure it is turned off whenever plugging or unplugging the TRS cable. As a good practice you shouldn't plug and unplug any cables with phantom power on anyway, particularly if you like your expensive condenser mics.

    Ken

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  10. #20 by Michael Lapke on 04-11-2018
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    Just received some more information from our CARE techs regarding this, just to clarify:

    The XLR and TRS output signals on the UMC404HD are identical, so there shouldn't be any difference in those signals. In addition, those outputs are IMPEDANCE BALANCED which is sort of a "Pseudo-Balanced" tactic that is used. The reason for this is because with products like these you tend to have a mix of end users with Balanced and UNbalanced gear. The output needs to work as close to identical as possible, whether it's going into a high end TRUE balance amp input or a low end unbalanced amp. By using IMPEDANCE BALANCE we've added versatility to the product, but at a potential minimal loss in fidelity.

    While the THD showing up on your scope looks aggressive, it's not actually being heard on your outputs is it? This is what CARE was referring to in their initial reply to you.

    So further down the audio chain, your UMC404HD XLR inputs are more tolerant to receiving an Impedance Balanced input then the TRS inputs are. It is not a fault or design flaw. So unless you are hearing these harmonics in your output signal, or if you are hearing different signals on your XLR vs TRS outputs, then I think it's fair to say that the unit is operating as intended.

    Michael Lapke
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