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A clear reason to run your DAW at higher sample rate ??

Discussion in 'Computing' started by pcrecord, Nov 8, 2019.

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  1. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    Hi gang,

    I've been listening to this youtube channel for a few weeks and it's been twice that this subject as been discussed.
    In the video he clearly demonstrate a reason why you'd want to run at higher sample rate or carefully use plugins that has oversampling..

    I hope to get your opinion on this.. ;)

     
  2. Makzimia

    Makzimia The Minstrel Well-Known Member

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    Edit: next time I’ll read the content instead of just the topic... sorry guys.. it’s been a rough few weeks.

    Tony
     
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  3. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    I'm hearing a resonance in his room just below 100Hz.
     
  4. Boswell

    Boswell Moderator Distinguished Member

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    The effect he is describing is not a fault of the sampling rate that the DAW is running at, as it would happen at any rate. It's a problem of poorly-designed plug-ins, particularly those that impart deliberate distortion.

    As the video advocates, plug-ins may need to up-sample by a factor of 2 or 4 on the DAW rate, do their processing, then low-pass filter and decimate at their outputs. This is in order to minimise the amplitude of out-of band generated components that would otherwise appear in the DAW's passband.

    Computationally intensive, but necessary.
     
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  5. audiokid

    audiokid Chris Staff

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  6. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    So I should have called this "Reason to use only plugins with oversampling" ;)

    I was about to remind you that the artifacts created were in fact in the frequency range of the end product, either CD or mp3... But that's ok we all have our ups and downs..
    I'm sorry my title might have been missleading. Hope you get through your rough times soon.. !
     
  7. Boswell

    Boswell Moderator Distinguished Member

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    No, not really. A non-effects plug-in does not easily generate distortion as long as moderate care in taken in its design and coding; the plug-in would be expected to run at the sampling rate of the host DAW without showing any spurious harmonics (spurs) in the passband.

    It's only the plug-ins whose purpose is to distort the incoming audio that inherently generate harmonics, and their authors need to consider carefully how to deal with the resultant aliasing. Running the plug-in at a multiple of the DAW sampling rate at least gives them some headroom in which to work, but even starting from there, they do have to get it right. I would not expect a plug-in that does deal properly with spurs to advertise that it runs at a higher rate, but the authors might understandably want to promote their product by mentioning the reduction in spurious harmonic distortion.

    An interesting case is a DAW such as Harrison Mixbus 32C, where a small amount of carefully-crafted non-linearity is designed-in to emulate some of the sonic character of large-format analogue mixers. It's subtle but effective, and I've run tests that do not show any evidence of spurs in the DAW passband.
     
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  8. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    It would be nice to know how many and which aren't designed correctly.. I'll make some tests on those I own when I get time.. ;)
     
  9. audiokid

    audiokid Chris Staff

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    Awesome, Bos, we're always learning from you.

    I had to search "spurious harmonics" (spurs) and found this which I will add to our glossary once you confirm its meaning :). This is what google gave. Is this correct, Bos?

    Harmonic Spurious. Harmonics are signal impurities that occur at integer multiples of a fundamental signal. ... Then, the signal generator is tuned to the fundamental frequency with the power level unchanged. The spectrum analyzer measures the resulting harmonic response relative to the reference amplitude.
     
  10. Boswell

    Boswell Moderator Distinguished Member

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    I think it's likely that it is only plug-ins that produce audible deliberate distortion would cause this sort of a problem. Even the built-in subtle colouration in Mixbus does not result in anything detectable in the passband. However, it is possible that the Harrison coders are fully aware of the effect and do indeed run their analogue-emulation code at a higher effective sampling rate.
     
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  11. Boswell

    Boswell Moderator Distinguished Member

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    It's fine for applications like ham radio, and maybe analogue hi-fi. The field of digital audio is a bit different, because generated harmonics that fall above the Nyquist frequency wrap around back into the audio band, creating components at spurious frequencies that are related to but are not multiples of the original fundamental. Because of this, they are grating on the ear and they should not be called harmonics. I use "spurs" because I think it's a good term, as it has the connotation of something sharp and unpleasant. The Google definition does not deal with these non-multiple components.

    I had a quick wider look online, and the subject does not seem to be covered very well in relation to digital audio. Here's a page that shows the difference between harmonics and spurious signals in an r.f. context. The result is similar in digital audio, but the mechanism of production is quite different. I'll have to search a bit further to find something suitable for the RO glossary.
     
  12. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    Yeah, Mixbus isn't the first I would put on the trial stand.. It's a well made software.
    No, I'm curious about some from UA, many emulations of hardware introduce distortions and harmonics.
    I'm guessing some daws are more prone than others depending on their floating point.
    When I compared Sonar Reaper and Samplitude, I discovered that UA comp2a was producing harmonics abobe 20khz only on Samplitude.

    Also some plugins do have adjustable overclocking, it might not be a good idea to deactivate it to save CPU or achieve lower latency
     
  13. audiokid

    audiokid Chris Staff

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  14. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    I instantly thought of waves, who make very bright pluggins generally and can get harsh. I find that their emulations are often bright and grainy, relative to their non emulation plugs.

    I wonder how this result varies with session sample rate, and pluggin version, and pluggin format type.

    Its interesting that in sam its up at 20khz, samp seems to do something to the high end. The question left unresolved from your video series, is does samplitude add high end, or is it preserving high end, when the others arent?
     
  15. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    When testing, I was working at 96khz on each Daw and using the same plugins with the same settings.
    I doubt Samp would add HF.. I would suspect that the other DAWs just let go of those frequencies on the premiss that we can't hear them.
    But I don't have access to the codes and I would not understand a thing even if I did.. ;)
    I'm going to make some more tests soon.. I'll let you know if I can come to more info on this aspect !
     
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  16. Makzimia

    Makzimia The Minstrel Well-Known Member

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    While I can’t hear probably above 13-14k anymore... Logic Pro, Cubase and Studio One at the very least do not limit frequency. That is entirely down to recorded source :). The only real restrictions are bad idea to drive over unity at master output.

    Tony
     
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  17. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    13-14k... sorry to read that..
     
  18. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    Id be curious if 192k exemplifies the 20khz boost. This might rule out if its filtering (or lack of filtering) related to sample rate, or just something inherent in the pluggins coding.

    Code is something i dont understand, i do remember boz saying he inspected audacity's code and felt confident it was sample accurate.
     
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  19. Boswell

    Boswell Moderator Distinguished Member

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    Well remembered, K! I still use Audacity for simple stereo capture and store, as I am confident that with no EQ dialled-in, 24-bit ADC samples are unmodified in their path to disc. That's more than can be said of some other DAWs.
     
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  20. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    Is there a way to test if Sam is adding HF info, or just reproducing it when others don't? I guess it would be difficult to asses if it was attributed to the capture side or the summing side.
     
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    The New AT5047 Premier Studio Microphone Purity Transformed

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