4 ms·

No, jitter is not a problem. It is more than a stretch to go from "jitter as a theoretical problem" to "jitter as an actual problem" - it is absurd. Don't even

by pslam 12y ago

No, jitter is not a problem. It is more than a stretch to go from "jitter as a theoretical problem" to "jitter as an actual problem" - it is absurd. Don't even give this credence. The only way to make jitter audible is to do it deliberately, to the extent that the DAC would have difficulty even locking to it. At that point, it would likely end up dropping samples, and we're not really talking about digital audio any more. Audio marketing has been using crap like "digital jitter" as one of their snake oil sales tools for as long as digital audio has been commonplace. Don't give it even the slightest amount of publicity.

Florin_Andrei 12y ago
I used to design digital electronics in a past life. When the slave has locked onto the master clock, and remains there locked for a long time, it's game over. The slave becomes effectively a clamp-down filter on the master's real or imaginary deficiencies. Yes, the master does matter still, but a quality, stable slave acts as a damper. The slave's own jitter tendencies might be important - but then again, where do they end up? Mostly in the analog /dev/null sinkhole - the sampling frequency is far above the audio spectrum, the jitter components are too, mostly (unless it's low-freq drift), and the output of your DAC has a steep downpass filter. Jitter components are obliterated. That's assuming that jitter would matter at all even if it was not filtered out. But if a DAC is flickering that badly that you could hear it, it's probably a piece of trash anyway. Make sure the actual digital-to-analog conversion (the last link in the digital chain) is done well, and don't worry about anything else. Yes, you can screw up DAC design and execution, but nowadays most DACs are very good. This is not your grandpa's radio.
TheOtherHobbes 12y ago
You must be unfamiliar with the AES and other papers that describe audible jitter and the threshold at which it starts to become audible. See e.g. "Eric Benjamin and Benjamin Gannon, "Theoretical and Audible Effects of Jitter on Digital Audio Quality", Preprint 4826 of the 105th AES Convention, San Francisco, September 1998" or "The Effects of Sampling Clock Jitter on Nyquist Sampling Analog-to-Digital Converters, and on Oversampling Delta-Sigma ADCs, 87th Convention of the Audio Engineering Society, October, 1989" or Ashihara and Kiryu, etc (2005) https://www.jstage.jst.go.jp/article/ast/26/1/26_1_50/_pdf https://www.jstage.jst.go.jp/article/ast/26/1/26_1_50/_pdf
- pslam 12y ago
  I am quite familiar and in fact that paper concludes that jitter is not detectable in normal consumer equipment: "About 25% of the listeners detected jitter when its size was 500ns. When it was 250ns, however, no listener could discriminate the sounds." ... "Nishimura and Koizumi made attempts to measure actual jitter of various DA systems during reproduction of music signals. They could not detect any jitter larger than 3ns in their measurements." ... "So far, actual jitter in consumer products seems to be too small to be detected at least for reproduction of music signals" ... CONCLUSION "The threshold values seem to be sufficiently larger than the jitter actually observed in various consumer products."
  - cnvogel 12y ago
    You should point out that typical jitter on the digital interface will be in the order of few 100 PICOSECONDS...
    - Joeboy 12y ago
      and is totally unrelated to any jitter on the storage system (unless it's so slow that it can't keep up with the DAC, which is unlikely to happen unless it's a 20th century hard drive or connected by a wireless/internet connection).

by pslam 12y ago

Florin_Andrei 12y ago

I used to design digital electronics in a past life. When the slave has locked onto the master clock, and remains there locked for a long time, it's game over. The slave becomes effectively a clamp-down filter on the master's real or imaginary deficiencies. Yes, the master does matter still, but a quality, stable slave acts as a damper. The slave's own jitter tendencies might be important - but then again, where do they end up? Mostly in the analog /dev/null sinkhole - the sampling frequency is far above the audio spectrum, the jitter components are too, mostly (unless it's low-freq drift), and the output of your DAC has a steep downpass filter. Jitter components are obliterated. That's assuming that jitter would matter at all even if it was not filtered out. But if a DAC is flickering that badly that you could hear it, it's probably a piece of trash anyway. Make sure the actual digital-to-analog conversion (the last link in the digital chain) is done well, and don't worry about anything else. Yes, you can screw up DAC design and execution, but nowadays most DACs are very good. This is not your grandpa's radio.

TheOtherHobbes 12y ago

You must be unfamiliar with the AES and other papers that describe audible jitter and the threshold at which it starts to become audible. See e.g. "Eric Benjamin and Benjamin Gannon, "Theoretical and Audible Effects of Jitter on Digital Audio Quality", Preprint 4826 of the 105th AES Convention, San Francisco, September 1998" or "The Effects of Sampling Clock Jitter on Nyquist Sampling Analog-to-Digital Converters, and on Oversampling Delta-Sigma ADCs, 87th Convention of the Audio Engineering Society, October, 1989" or Ashihara and Kiryu, etc (2005) https://www.jstage.jst.go.jp/article/ast/26/1/26_1_50/_pdf https://www.jstage.jst.go.jp/article/ast/26/1/26_1_50/_pdf

pslam 12y ago
I am quite familiar and in fact that paper concludes that jitter is not detectable in normal consumer equipment: "About 25% of the listeners detected jitter when its size was 500ns. When it was 250ns, however, no listener could discriminate the sounds." ... "Nishimura and Koizumi made attempts to measure actual jitter of various DA systems during reproduction of music signals. They could not detect any jitter larger than 3ns in their measurements." ... "So far, actual jitter in consumer products seems to be too small to be detected at least for reproduction of music signals" ... CONCLUSION "The threshold values seem to be sufficiently larger than the jitter actually observed in various consumer products."
- cnvogel 12y ago
  You should point out that typical jitter on the digital interface will be in the order of few 100 PICOSECONDS...
  - Joeboy 12y ago
    and is totally unrelated to any jitter on the storage system (unless it's so slow that it can't keep up with the DAC, which is unlikely to happen unless it's a 20th century hard drive or connected by a wireless/internet connection).