Computer Audio Asylum

• OK, I can agree with that, but that's not what I said - bwb 11:34:37 02/18/12 (2)
  In Reply to: RE: you seem to have a problem with deductive reasoning and staying on topic posted by Tony Lauck on February 18, 2012 at 11:11:14

  .
  
  "The sound will be different each time the play button is depressed. "
  
  That was not the scenario I described.
  
  My point was.....
  
  If you wait one second to press the button or not the bit stream to the DAC will be exactly the same barring any outside influences such as AC line fluctuations. Waiting one second is a delay or a latency, therefore the fact that there is a latency does not affect the sound.
  
  However, changing a setting in the computer that results in a change in latency could also affect the sound due to other secondary effects. It would be easy to incorrectly conclude that the change in delay caused the change in sound.
  
  It is also not the same reasoning as bits are bits i.e. perfect sound forever and all bit perfect music players must sound the same. In this case concerning latency everything is identical except for the time of arrival. Different players affect many other parameters of the computers operation so it is not illogical that they would sound different.
  
  I think I've exhausted that line of reasoning. If the others still insist that the two are linked then I'll never convince them otherwise.
  
  
  
  
  
  
  
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  • RE: OK, I can agree with that, but that's not what I said - Tony Lauck 12:12:20 02/18/12 (1)
    In Reply to: RE: OK, I can agree with that, but that's not what I said posted by bwb on February 18, 2012 at 11:34:37

    You don't have to agree with me. I agree with you. :-)
    
    (My comment about the sound differing each time was the most obvious example of how correlation might not be causation. Many reports of "differences" fail to deal with the most basic cause of audible differences, namely varying moods on the part of a listener.)
    
    What does matter is the buffer size and buffer load strategy. This determines the period and duty cycle of the bursty buffer loading processing, which translates into periodic power supply load and thereby periodic jitter. If this periodic jitter is of very high frequency it will be out of the audio range or filtered out by the PLL in a DAC. However, an attempt to run with very low buffer sizes won't work unless latency is low enough, since otherwise there will be buffer underruns. It's conceivable that changes in actual latency will affect the timing of several levels of processing in the computer and hence the waveform imposed on the power supply rails, even if the buffering parameters are unchanged. This will affect the spectrum of jitter and hence potentially the sound. However this will be a third order effect (jitter itself is already a secondary effect due to some degree of reclocking at the DAC). Given that the advocates of low latency have not listed all the variables they are investigating and how they are controlling for them there is no reason to pay much attention to their conclusions. However, the observations are often interesting.
    
    Some people have measured spectra of the analog output of a DAC that shows jitter induced sidebands whose position varies as the buffer reload rate in a computer based transport vary. This effectively puts the lie to those know-nothings who claim "bits is bits". If one creates periodic (deterministic) jitter one can use synchronous detection and measure jitter artifacts that are well below the noise floor of a DAC (and associated measurement equipment. One can also put a scope on the power supply rails in the computer and observe how the waveform varies as the computer configuration changes. It is possible to get to the bottom of these issues if one is so inclined. I'm not, because I am happy with how my system sounds as is. I was willing to spend perhaps 100 hours setting up my speakers and room, a task that resulted in a dramatic improvement in the fraction of recordings that were enjoyable and IMO a much more useful task than further reduction of latency.
    
    Tony Lauck
    
    "Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
    
    

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    • Amen brother Tony! /nt - bwb 13:07:24 02/18/12 (0)
      In Reply to: RE: OK, I can agree with that, but that's not what I said posted by Tony Lauck on February 18, 2012 at 12:12:20

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