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Upsampling downloaded CDs on a PC using Foobar2000 for USB/DAC playback. Any opinions?

Discussion in 'DACs' started by wyn palmer, Dec 3, 2018.

  1. wyn palmer

    wyn palmer Active Member

    Messages:
    338
    I have saved my entire CD collection on a laptop and I use an external DAC for playback.
    I'm thinking of experimenting with a Topping D50 which can accept a wide range of digital audio data rates and bit depths to see what effect upsampling my CD collection has. I normally play back via USB using Foobar2000 which has plug ins that can be used for this.
    Has anyone tried doing this or something similar and if so is what was the result?
    Opinions on upsampling that can be found on the web- as always- are mixed, but there may be some evidence to suggest that it has an audible benefit even if it does nothing to increase the actual amount of data available, so I'm curious.
     

     

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  2. KeninDC

    KeninDC Speedfreak Jive Subscriber

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    12,246
    Location:
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    Upsampling what to what? MP3 to WAV? WAV/PCM to "hi-rez"? DSD? I know you know this, but you cannot put back what has been taken out or is not there.

    Might be a fun experiment with one song you know really really well. If your entire CD collection is ripped to MP3, you may want to consider ripping it all over again to PCM. Perhaps in FLAC. Knowing your collection is lossless will help you sleep at night although 320 kbps zealots might say otherwise.
     
    KrisM, Bill Ferris and spark1 like this.
  3. wyn palmer

    wyn palmer Active Member

    Messages:
    338
    As I said, stored CDs (i.e. PCM at 16 bits/44.1kHz mostly) - not MP3, not DSD etc. I can, potentially, upsample to the 2.8224MHz (24 bits, 88.2kHz) DSD rate in software or even higher.
    In fact. I have seen plausible recommendations for conversion/upsampling of Red book PCM to quad or Octal rate DSD as being the only way to go!
    Everything is error corrected and compressed using FLAC and is backed up. Upsampling is dynamic and doesn't affect the stored files.
    The DAC automatically detects the source data rate etc. and converts accordingly.
     
    Last edited: Dec 3, 2018
  4. gvl

    gvl Super Member

    Messages:
    1,044
    There are conflicting opinions on this matter. I would suggest to download a trial version of HQ Player and decide for yourself.
     
  5. wyn palmer

    wyn palmer Active Member

    Messages:
    338
    I did some upsampling to DS256 for several CDs that I had saved on my PC. I used Foobar 2000 with SOX and the free trial version of Jriver. I used several CDs that I also had the vinyl issue of, and in a couple of cases I also had a 15IPS 1/4" tape.
    I had three partcipants perform a listening test. It wasn't really blind so I know it's not truly valid- however...
    The conclusions? For one of the two cases that I had a tape for the tape was preferred. In all other instances the vinyl was preferred. BUT the upsampled CD was far closer to the vinyl than the initial PCM Red book CD with any of the 7 reconstruction filters that were available on the D50, and much better than the NOS tube output DAC (MHDT Havana with Halide S/PDIF) that I also had.
    Of course the vinyl rig is 50x more expensive than the D50 and an order of magnitude more expensive than the NOS rig.
    The tape deck is c. 2x the cost of the NOS set up- but the media, of course, is an order of magnitude more expensive than any of the others.
    So in general the ranking was, in terms of sound quality:
    Tape deck, vinyl rig, DSD256 upsampled, ultra modern PCM DAC with reconstruction filter, decade old NOS tube DAC.
    Basically, the DSD experiment seemed to be a success and if anyone is interested I would recommend that they give it a shot.
     
  6. cpt_paranoia

    cpt_paranoia Well-Known Member

    Messages:
    931
    For a DAC that uses an oversampling filter in the DAC chip itself, you will often find there are a number of oversample rates you can choose, and different digital filter algorithms. Whether you can choose which of these to use is another issue.

    So, the question would be whether the oversampling and filtering options in the DAC are better than those options provided by the equivalent functions in your media player software.

    Oversampling is means to relax the requirements of the anti-imaging filter required on the DAC output to reduce the sinc function imaging inherent in a zero order hold sample data system.

    Experiment with all the oversampling and filtering options available to you, and pick the one you like best.
     

     

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  7. wyn palmer

    wyn palmer Active Member

    Messages:
    338
    This is what I finally did- I upsampled the 44.1k 16 bit Red book source to 176.4kHz 32 bit which I believe (please correct me if I'm wrong) provides a 0-22.05kHz signal, a 154.4kHz to 176.4kHz image and a 176.4kHz to 198.4kHz image (following the sinc function) etc. I did not, eventually, end up converting to DSD- I could not tell any audible difference from the upsampled PCM. I then used the Foobar2000 SOX/SSRC plug in to apply an apodizating anti-aliasing filter that remained flat at 20kHz, but rolled off gradually to be -146dB at c. 40kHz. This eliminated the supersonic noise prior to the image frequencies that seems to be generated by the upsampling.
    The DAC reported a 176.4kHz PCM input rate and the built in filters which I believe are applied to the input stream and are frequency scaled appropriately, were applied relative to that, so presumably they are now operating c. 80kHz.
    We could not hear any effect due to the built in DAC filters, but we were convinced that the upsampled output sounded better with the SOX/SSRC filter in place.
    I'm still trying to determine if there's any rational way to perform a measured difference analysis of the original and upsampled bit streams before converting to analog.
    I also tried upsampling to 176.4kHz 24 bit and 352.8kHz 24 bit and could not hear or measure any significant difference in the analog output with the DSP set as above, so I just kept it as it was at 176.4kHz 32 bit as the CPU didn't seem to be having any issues (15% utilization) and there were no glitches that could be heard.
    By the way, the DSP plug in that does the upsampling/digital filtering can be switched in and out with a single mouse click- reverting the input to 44.1k 16 bits on the fly. The DAC reacts accordingly switching the reported input to 44.1k 16 bit PCM.
    The difference in the supersonic behavior can be seen on a spectrum of the analog output, but the audio signal amplitude remains the same. There is a small click produced by the transition so it's not completely non-detectable.
    This made doing an A/B test simple.
     
    Last edited: Dec 10, 2018 at 5:51 AM

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