Mix out of Qu 32 to PC

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This topic contains 10 replies, has 5 voices, and was last updated by Profile photo of Josh Josh 1 year ago.

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  • #90969
    Profile photo of Josh
    Josh
    Participant

    Hi all.

    First of – my knowledge is very limited!
    I run the AV desk for our church.

    Got a query about this board.
    We livestream our services over YouTube. So take audio out of the board into the PC. This is done via mono mix out into a Blackmagic Presenter. This Blackmagic takes the audio in and video in and sends it to the PC via USB into OBS. It then goes from OBS to YouTube.

    However the audio that comes out has a very bad crackling noise over it. Basically you can hear the audio fine but there is always this static crackling.

    So want to find out –

    a) – Is this way of getting audio from the mixer to the PC best?
    b) – If not, what is recommended?
    c) – Can I take the USB out from the back of the mixer and just get audio out from this?
    d) – Any thoughts on the reason behind this crackling?

    Any advice on the easiest way to do this.
    We simply just want to get the audio from the mixer to the PC. Nothing fancy!

    Many thanks

    #90972
    Profile photo of garyh
    garyh
    Participant

    You need to figure out if the crackling noise is starting at the board, the Presenter, or the computer.

    Is the crackling noise in the board headphones when PAFLing the mix? Try a different XLR cable from the board to the Presenter. Try a different USB cable from the Presenter to the PC. Try removing USB devices from the PC one at a time to see if the noise stops. Make sure nothing is running in the background on the PC that might be stressing the CPU while streaming.

    That’s all I can think of right now.

    #90974
    Profile photo of volounteer
    volounteer
    Participant

    @josh

    Need a lot more info.

    could be several reasons for your noise or other problems.
    My PC has crackling noises when the levels are too low to mask them.

    You have many outputs you can use from the mixer.
    The best is the one that works for your total set up.
    We use the matrix. Other outputs could work well too.

    What are the connectors and impedance levels and voltage levels in the chain?
    That is the biggest problem our church has for livestream.
    For mere posting we can cut and paste the audio onto the video from an easier recording approach.

    Do you really need all that complexity?
    [I have trouble following your description as I do not use BM gear or OBS]
    If you want the simplest way that is definitely overkill.

    Why are you using mono?
    What processing are you doing in the Qu?
    Are all the cables grounded correctly?

    Yes you can take the audio from the mixer via usb but then why use BM OBS?
    We send audio to camera recording video and then send that to utoob.
    For batch we may process audio and sync with video in another program before uploading.

    #90975
    Profile photo of Mike C
    Mike C
    Participant

    On the Presenter I assume your using the the XLR input.
    Do you have the input for line level? It’s in the the set up menu.
    The crackling noise could be input over load distortion if it is set
    to mic level input.

    It’s also possible you may need an isolation transformer between the mixer and
    the Presenter if your getting buzz and or hum in the audio.

    You can use the USB B jack to send audio to a computer, you would need to go into
    the IO set up menu, select the USB tab and then select the tracks that your
    computer is looking for to pull audio from and set those tracks to be the
    mix you want to send to the live stream. Tracks 1 & 2 seem to be what most computers
    pick up audio input from….unless you are using multi track recording programs.

    For your live stream purpose you should stay with sending the audio into the Presenter,
    sending the audio directly to the computer would certainly cause audio video sync timing issues.

    #90983
    Profile photo of Josh
    Josh
    Participant

    Guys many thanks for the replies.

    Apologies for the lack of info.
    It has been a while since I have been able to test/diagnose anything. Due to the quarantine it has been on my mind so thought it was about time to explore the issue.

    I hope to get a chance to pop in this week. I will try a few things that have been suggested above and will report back with results.

    Thanks

    #91005
    Profile photo of DoctorG
    DoctorG
    Participant

    It is almost impossible to troubleshoot from afar a problem like this. For example, you describe the noise as “crackling,” but terms like this are very subjective.

    A broken cable or loose connection will certainly cause “crackling” which is intermittent. If the noise is very consistent, it is probably something else.

    Several good possible solutions have been proposed previously. All of them need to be considered.

    One thing I did see mentioned by Mike is that the output level of the mixer may be too great for the PC input. That will lead to overload or clipping distortion that may sound like “crackling.” Reducing the signal level from the mixer should make that problem go away.

    Depending on the type of connector you are using, you could be taking a balanced or an unbalanced signal from the mixer. The PC needs an unbalanced signal, unless your PC has a card that takes a balanced signal. The best way to get that is to use a transformer adapter that converts the balanced signal into an unbalanced signal. Mike also suggested this.

    However, as Mike mentioned, the XLR connector on the PC, if one exists, is likely to be designed for a mic-level input, and the mixer output will be too great for this, so an attenuator of some type would be needed.

    Good luck!

    #91008
    Profile photo of Josh
    Josh
    Participant

    Thanks again for all the replies.

    I had a bit of time tonight to go in.
    Most of the system was setup by a company before I did things. So I’m not 100% sure on why certain things have been done etc.

    I’ve always thought that a simple cable from stereo mix out to line in on the PC would work. I had a got a cable for this a long time ago but never had time to try.

    So before I tried to diagnose the issue with the Blackmagic way I tried this way. I plugged it all in via a 3.5mm hum-eliminator I had as well.
    The result – perfect.

    In OBS I’ve then set a slight delay to sync the audio and video together.
    I haven’t bothered looking into the other issue as this way seems to work spot on. I tested it over and over and actually had to turn some settings down as it came out pretty loud.

    Thanks for all the replies and suggestions. Hopefully this will work all okay. But if not I can dive deeper and diagnose with the BM.
    The only thing I had tried in the past was turning down the line level in the PC settings. This did turn down the crackling. But I had complaints that the livestream was too quiet. This seems to line up with some things you guys have suggested.

    Cheers guys 🙂

    #91010
    Profile photo of Mike C
    Mike C
    Participant

    Keep in mind most 3.5mm inputs on a computer and or that matter your non professional
    handy cam camcorders are a stereo mic level unbalanced input.

    Taking a line level balanced line input to a 3.5mm stereo input will not sound very good as in “thin sounding”, distorted to hardly any level.

    A straight through balanced connection either an XLR or 1/4inch TRS plug to a 3.5mm TRS plug with cause phase cancellation at the stereo input due to the balanced line carrying the signal 180 degrees out of phase on what would be the tip and ring of the 3.5mm plug.

    #91023
    Profile photo of Josh
    Josh
    Participant

    Thanks Mike.

    This is the cable I am using -https://www.amazon.co.uk/dp/B01BYGQ61K/ref=cm_sw_r_cp_api_i_xSRLEbQB11T8A

    So what you are saying is I’m taking a balanced signal from the mixer and putting it into the unbalanced line in port on the computer?

    I remember there being a unbalanced/balanced converter kicking about – I think it was Kramer. Would this need to be used then?
    Or is it the actual input port on the PC that is the issue?

    From my testing the audio sounded fine. But that doesn’t mean that it is correct!

    #91034
    Profile photo of Mike C
    Mike C
    Participant

    This is the cable I am using -https://www.amazon.co.uk/dp/B01BYGQ61K/ref=cm_sw_r_cp_api_i_xSRLEbQB11T8A

    So what you are saying is I’m taking a balanced signal from the mixer and putting it into the unbalanced line in port on the computer?

    I remember there being a unbalanced/balanced converter kicking about – I think it was Kramer. Would this need to be used then?
    Or is it the actual input port on the PC that is the issue?

    From my testing the audio sounded fine. But that doesn’t mean that it is correct!

    The cable that you linked to would be correct for what you are doing.
    It is wired to unbalance the XLR connections and send each channel + to the 3.5mm TRS plug.

    The only thing that it will not do is provide any isolation for hum or buzz, but in your case it sounds like that is not an issue.

    #91035
    Profile photo of Josh
    Josh
    Participant

    Maay thanks for confirming that!
    Well I will stick with this and see how it goes over the next few weeks.

    Thanks for bearing with me 🙂

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