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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

    jgatie
    March 1, 2017

    Simple question...

    Do you believe digital audio has reached perfection?

    Simple answer: No.


    Another simple question....


    Do you believe digital audio, outside of mastering/production techniques, can be improved by playback resolutions greater than 16/44.1?
    March 1, 2017


    Another simple question....


    Lol. You are baiting him!
    This brings to mind a DAC I once had, made by Musical Fidelity - UK, not So Cal! It was bigger in every dimension than the standard stereo amp, and it weighed about twice as much. Massive heat sinks at the sides because the output stage had a couple of valves - Mil spec ones. It had feet that glowed - the colour changed from blue to red to indicate warm up complete!
    It also had a selector for sampling frequency options with an LED indicator for chosen selection that read 24/96 or 24/192. No prizes for what sounded better when one noticed what the read out said.
    It cost me about GBP1000. I ended up gifting it to a friend; I did not have the integrity levels needed to sell the beast to him. He was thrilled beyond measure, so someone is getting value from it, which is good.
    The DACs I now use are sitting somewhere inside in my play 1 units/Connect Amps along with all the other good stuff:D
    Peter Mc
    Peter McAuthor
    March 1, 2017
    It's a simple question that deserves it's own thread. I'll start one.
    "The presence of those seeking the truth is infinitely to be preferred to those who think they've found it" - Terry Pratchett
    March 1, 2017
    Good idea Peter; name it well!
    jgatie
    March 1, 2017
    Actually Kumar, the question was for you. I wanted clarification on your 'No' answer to the previous answer (which i agree with).

    I already know what his answer is. 😉
    March 1, 2017
    Hmm..let's leave that for the thread that Peter said he will start.
    Peter Mc
    Peter McAuthor
    March 1, 2017
    New topic created - let's move the discussion there.
    "The presence of those seeking the truth is infinitely to be preferred to those who think they've found it" - Terry Pratchett
    March 1, 2017

    I really like the Sonos gear, my Play 5's are fun, the Connect Amp does a fine job for the bedroom, the interface and the way I can search Soundcloud, Spotify and Tidal is great, plus being able to stream from my iPhone is also nice, and now you can see the Sonos gear as endpoints/zones from Roon it is a even better, but I do wish there was a higher end unit for serious listening on the main system.

    let's offer some new product, and give us a reason to buy more gear from you.


    Quoting above from your first post on this thread, and your later complaint that you are being stifled, what was your expectation from the quoted parts of the post?

    Conversation about when Sonos will do MQA or Hi Res, and why it is taking them so long to do so? Or something other than that?

    And if you were someone that had never heard any difference in a blind test to improvements that can be attributed to things like MQA or Hi Res, what would have been your response to this post?

    Trust me when I say that these aren't rhetorical questions.
    Enthusiast II
    March 1, 2017
    Lots of questions, comments to respond to.

    Do I think hi res is better?
    Not to the point where I have bothered with it.
    There have been a few hires albums that people have raved about that I have played back into my Meridian DSP5200s (they have a dac built in) where the album has been better than the 16/44 version I have. A smoother top end, but more importantly a much bigger soundstage.
    Do I think this is because of the fact they were 24/96?
    Probably not, probably just a better recording or better mastered. But if that recording is noticeably better I would like the opportunity to be able to play it.

    Do I think MQA is worth having?
    There is something very impressive with MQA on a lot of tracks, there is a real sense of realness. I won't begin to describe what that is, but there really is something that makes recordings feel very raw without feeling edgy, most of the time. Some versions I have actually not liked as much as it has taken away some of the smoothness, but these tend to be my rocky type tracks that I wouldn't listen to anyway, but someone into that kind of music may think they are far better, I don't know?
    Some tracks I have not been able to tell a difference with.
    But again, being able to play the MASTERS (MQA) albums going forward would be nice.


    If being told I am deluded for thinking the above, or I am an 'audiofool' is the normal response on here then what is the point of having a forum?
    I disagree with what a lot of you have said about DAC tech, in an ideal world the DAC would be perfectly flat, but DACs are not perfect and nor is the rest of most peoples systems, and when listening at home I don't want to hear the same sound as a mixing desk with studio monitors. I had Lexicon gear before with Dunlavey speakers, and while many said that was the closest they had heard to a live instrument/vocal, I really didn't like the sound at all, far from 'nice'. For me it is about being able to play the content that is out there, and finding a system I 'like', not finding something perfect, just something I like, hopefully that happens at a decent price too.

    Having said that, my Connect is very obviously doing something negative to the music being played through Tidal and I am using the digital out. I came on here as I wanted to know what that was, hence finding this thread.


    Kumar, what was I hoping for?
    I was hoping there may be a reply from people describing a roadmap of what products were on the way to take advantage of the newer formats and to compete with products from the competition that are now on the market.
    I didn't realise there was such animosity towards such requests.
    I guess I thought that as people were Sonos owners, where they are not falling for the felt tip pen on a CD, or the $1000 Cat5 cable, they would be a bit more laid back, a little less patronising and less hostile than on other forums, I was obviously very wrong. My fault as for some reason I read page one of this thread and then it skipped to the last page, I had completely missed the replies in between, if I had seen those I wouldn't have bothered posting, but I didn't see them so I did post.
    March 1, 2017

    I was hoping there may be a reply from people describing a roadmap of what products were on the way to take advantage of the newer formats and to compete with products from the competition that are now on the market.

    One problem here is that the search function is lousy; you would have been better served reading and then posting on the threads that are on the MQA subject, but finding them here is a challenge.
    I have no personal experience with MQA, but on the hi res subject, people here are fed up with all the unjustified hype that exists around it, that dates back to 2007 or so. Your point about just wanting to listen to the files you have that are in that format is a good one; there is a way to this via a one time downsample and Sonos have also spoken once about seeing if this can be done on the fly every time. That said, there has been no further talk on those lines since, so the one time downsample is your only option.
    As to a roadmap, none of us have any access to the information needed to draw that and you won't see that here even from Sonos Staff. All that is known are the stated present priorities of Sonos that are in the area of voice control, streaming services and integration into home automation. This, in response to what Sonos sees on the competition front. Clearly, they are not losing sleep over either Bluesound or Meridian. IMO, rightly so, though you disagree.
    At the same time, expect challenges if you make statements that Sonos isn't meant for high end audiophile listening, because that misleads existing and potential customers and those of us that have seen/used a lot of audiophile kit will not let that statement slide. There is also little belief here in golden ears.