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Peter Mc
Peter Mc
August 23, 2016
Question

Connect no longer bit-perfect?

  • August 23, 2016
  • 450 replies
  • 29769 views
It looks like the Connect is no longer bit-perfect. Here's my evidence: let's discuss this.

First, I constructed a wav file of pink noise with amplitude ramping up from zero to digital max and back to zero.
I play this through my Connect and record the SPDIF output from the coax output into my PC.
The recording uses a Scarlett 8i6 audio interface set to use the Connect as master clock.
I record into a DAW (Sonar) multiple times - all instances are identical.
However, this recorded signal is not quite the same as the original wav file - it can be up to -21dB different.
See https://www.dropbox.com/s/t8od479xo9hi5el/connect_diff.PNG?dl=1
Note the expanded scale on the difference (third) track.

It looks like the difference gets larger when the signal is larger. To confirm this, I import the
original and difference files into Matlab and plot the raw data (difference vs original). There is clearly audio compression
happening here. See https://www.dropbox.com/s/p1yq6wcqafvnhaj/diff_vs_orig.png?dl=1
The scale is such that digital maximum is 1.

There also appears to be a slight bias when the waveform is negative and the signal is below the
compression threshold. See an expanded version of the previous plot
https://www.dropbox.com/s/9001tl9mkle4wly/diff_vs_orig_zoom.png?dl=1

Happy to answer questions about the method and conclusions.

Cheers, Peter.

p.s. Volume is set to fixed - I haven't tried variable.
In a loopback test (8i6 out from DAW to 8i6 in, no Sonos gear involved), I get bit-perfect cancellation.
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      450 replies

      Show previous replies
      jgatie
      jgatie
      March 9, 2017
      Why wouldn't I be consistent? Has something changed about the biology of the human ear, the laws of acoustics, or the Nyquist-Shannon Sampling Theorem in the last 89 years?
        chicks
        chicks
        March 9, 2017
        Purveyors of Snake Oil haven't changed much either, lol. Heck, we even have a few in the White House now.
        gizze
        Enthusiast II
        March 9, 2017
        Why wouldn't I be consistent? Has something changed about the biology of the human ear, the laws of acoustics, or the Nyquist-Shannon Sampling Theorem in the last 89 years?

        I didn't say you shouldn't.


        You have an incredibly aggressive nature, every post of yours makes you seem like a very angry chap.
          jgatie
          jgatie
          March 9, 2017


          I didn't say you shouldn't.


          You have an incredibly aggressive nature, every post of yours makes you seem like a very angry chap.

          Attacking the messenger is the last bastion of defence for a failure.
          gizze
          Enthusiast II
          March 9, 2017


          I didn't say you shouldn't.


          You have an incredibly aggressive nature, every post of yours makes you seem like a very angry chap.

          Attacking the messenger is the last bastion of defence for a failure.

          Jesus wept! 😃
            Kumar
            March 10, 2017

            Jesus wept! :D
            I agree; even he would have:D

            Since you have deigned to return: any comment on the hydrogen audio discussion on MQA that I provided a link to?
            gizze
            Enthusiast II
            March 10, 2017
            No. I read through it last night and it is just 'same old, same old'.

            I don't enjoy arguing with people, and all you lot want to do is argue. It doesn't matter what I say, I will get jagitate tell me that I'm wrong or I'm a fool so don't see the point.
              jgatie
              jgatie
              March 10, 2017
              No. I read through it last night and it is just 'same old, same old'.

              I don't enjoy arguing with people, and all you lot want to do is argue. It doesn't matter what I say, I will get jagitate tell me that I'm wrong or I'm a fool so don't see the point.

              Wow, I didn't think we'd be seeing the victim card so early from you. I honestly had higher hopes.

              And the childish respelling of my username? Nice touch. I'm sure you can find a large following on gaming console sites. 😃
              gizze
              Enthusiast II
              March 11, 2017
              No. I read through it last night and it is just 'same old, same old'.

              I don't enjoy arguing with people, and all you lot want to do is argue. It doesn't matter what I say, I will get jagitate tell me that I'm wrong or I'm a fool so don't see the point.

              Wow, I didn't think we'd be seeing the victim card so early from you. I honestly had higher hopes.

              And the childish respelling of my username? Nice touch. I'm sure you can find a large following on gaming console sites. :D


              If you weren't such an opinionated bigot I would bother, but what's the point?

              I know for a fact I'm not the only one who thinks this because of the PMs I have had from other members telling me they have just learnt to ignore you or don't post in the threads you post in, although pretty hard with such a post count as you do seem to be in almost every thread.

              Find a large following? Is that what you think people want? Is that why you have nearly 13000 posts on here? To get a following.
              Oh dear.
                chicks
                chicks
                March 11, 2017
                Wow. Do you even know the meaning of the word you're so casually using? Highly offensive, and far from true in this case.
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