QU16 Recording Clipping Issue:

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This topic contains 13 replies, has 3 voices, and was last updated by Profile photo of Tobi Tobi 3 months, 1 week ago.

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  • #117975
    Profile photo of Buffy
    Buffy
    Participant

    Hey there everyone,

    I have an enquiry regarding recording to a DAW (Reaper) with a QU16, and some issues I’m having with it. My primary goal is to be able to record the Mix9-10, with the recording to be of equal clarity to what I hear when monitoring the mix in PAFL. After following some advice that I received last year, I have done the following:

    – Changed the USB Audio input Tracks 17 and 18 to ‘Mix 9 L’ and ‘Mix 10 R’
    – Changed the Reaper input channel to 17
    – Changed the USB Audio input Tracks 1 and 2 to ‘LR L’ and ‘LR R’ so as to monitor the DAW
    – As both microphones are Channel 15 and 16, I have set both of these faders to 0
    – Set Channel 1 and 2 faders to 0
    – Monitored Channel 15 and 16 via. PAFL, and set the Preamp gain so that the meter peaks at +3/+6
    – Set main Mix9-10 fader to 0, PAFL peaks at +3
    – Recorded successfully

    So far, the connection is successful, I seem to know how to record, and the mix sounds amazing when I am monitoring it whilst performing via PAFL.

    I understand about the 18db analogue to digital discrepancy, however, whenever I try to normalise the recording, regardless of the method, the result is clipping/distortion when I approach anything close to a usable recording. Regardless of the LUFS, be it -35 before normalization, or -14 after, raising the recording to the right volume results in clipping/distortion.

    To try to troubleshoot this, I have done the following:

    – Changed USB Audio input tracks to 19 and 20 to test on a channel other than the one shared with QU Drive
    – Lowered the Preamp gain of Channel 15 and 16 (Mic channels), keeping the Mix9-10 fader at 0
    – Lowered the Mix9-10 fader to -10, kept the Preamp gain for mic channels the same
    – Lowered both at the same time
    – Recorded desktop audio of playback of a professional studio recording by raising the ST1 fader in Mix9-10, and tested it for clipping at the same recording/playback volume as earlier; no clipping, yet no normalisation or adjustments necessary

    I am not sure what I’m doing wrong here, but no matter what I try, I end up with a recording that clips when it reaches anywhere close to an adequate volume. It sounds absolutely perfect when monitoring directly with headphones from PAFL, or over monitors/PA. I have tried Googling the issue, and scoured the forum as best I could, but I couldn’t find anything specific. It’s likely to be related to the 18db analogue/digital discrepancy, but I feel like I’ve done everything to try to account for this. What am I missing?

    Any assistance would be majorly appreciated. If there is any pertinent information that I’ve left out, please let me know.

    Anyway, thanks in advance to anyone willing to offer a helping hand, and I hope you all have a Happy New Year!

    #117976
    Profile photo of Tobi
    Tobi
    Participant

    Do you normalize To lufs?? Or dbfs?

    #117979
    Profile photo of Buffy
    Buffy
    Participant

    I’ve tried both; -14 LUFS, -1dB/-6dB.

    #117984
    Profile photo of Tobi
    Tobi
    Participant

    Is the distortion there before normalization?

    #117988
    Profile photo of Buffy
    Buffy
    Participant

    Yeah, the clipping still occurs, regardless of whether or not I normalize first.

    Everything is recording correctly in regards to connectivity, it’s just the clipping that’s the issue.

    For further context:
    – I am running a simple vocals/acoustic guitar 2-mic input setup; SM81 and KMS-104
    – I have checked all cables, and have recorded into several different USB ports
    – Recorded both mics separately using Mix3 and Mix4

    I feel as though it’s an incredibly simple oversight that’s happened at some point, but I simply cannot figure out what happened. Happy to be labelled as a complete and utter moron if only someone could tell me the why hahaha…

    #117992
    Profile photo of Tobi
    Tobi
    Participant

    OK… first of all, if the clipping is present BEFORE any normalizing, than the normalizing has nothing to do with it. Then you need to check levels in QU. First Preamp. Then: When using EQ or Compressor, signal can also be increased, so even if preamp is OK, you could get clipping with EQ or Compressor settings. I have no QU at hand, but normally A&H desks have a red indicator lamp somewhere with the faders — they show ANY clipping. So when a lamp lights up, there is a clipping anywhere in the signal chain of that channel.

    The fact, that A&H “calibrated” the metering to -18dbFS should not matter in your case, this may reduce volume of the recording on your PC, but as you are recording in 24Bit, this really does not matter.

    Best Regards,
    Tobias

    #117994
    Profile photo of Buffy
    Buffy
    Participant

    There is no clipping present on the mixer itself during recording, even with my tests at higher Preamp gain. The current input levels are such that I can belt out a track and pretty much ride 0 on the QU Meter.

    Thanks Tobias!

    #117995
    Profile photo of Tobi
    Tobi
    Participant

    Do you get clipping from the analog outs? How do your waveforms look like?

    #117996
    Profile photo of Buffy
    Buffy
    Participant

    It clips the Main LR when played back after recording. Here are two recordings, the first being the original recording, and the second being after normalizing to -20LUFS.

    #118000
    Profile photo of Buffy
    Buffy
    Participant

    Second is after normalizing at -5db. Disregard previous comment, I can’t edit it.

    At the point of where things are in these screenshots, the audio isn’t anywhere near as loud as it needs to be, and pushing it any further in regards to normalizing or maximizing, or with faders, clips and distorts the audio immediately.

    #118003
    Profile photo of Buffy
    Buffy
    Participant

    It clips the Main LR when played back after recording. Here are two recordings, the first being the original recording, and the second is after normalizing at -5db.

    At the point of where things are in these screenshots, the audio isn’t anywhere near as loud as it needs to be, and pushing it any further in regards to normalizing or maximizing, or with faders, clips and distorts the audio immediately.

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    #118006
    Profile photo of Mike C
    Mike C
    Participant

    just to double check PFL your way though the mixer using headphones and listen for any distortion in the signal path before it hits the recording.

    Is it possible that during playback your are creating an internal feedback loop somewhere?

    #118066
    Profile photo of Buffy
    Buffy
    Participant

    Thanks all! Everything appears to be resolved now.

    Yes, as it turns out, it was a simple oversight.

    For whatever reason, I did not account for the DAW OUTPUT levels when initially calibrating my studio monitors. Simple, yet disastrous mistake that affected everything down the line.

    You live, you fuck up months worth of recording, and you learn.

    Have a great 2024 everyone!

    #118070
    Profile photo of Tobi
    Tobi
    Participant

    Good to know!

    Best Regards,
    Tobias

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