Question

Connect no longer bit-perfect?


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.

This topic has been closed for further comments. You can use the search bar to find a similar topic, or create a new one by clicking Create Topic at the top of the page.

453 replies

Hmm..let's leave that for the thread that Peter said he will start.
New topic created - let's move the discussion there.

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.
Userlevel 5
Badge +4
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.

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.

Do I think hi res is better?
Not to the point where I have bothered with it.

Now that I have read a little more about MQA, the quoted words are interesting.
Because on MQA, I find this essence:
"MQA attempts to approach the quality of the higher resolution file while using a compression technique that is closer to the CD end of things."
If so, it goes without saying that MQA cannot be better than the higher resolution file that it has compressed. At best it can be equal, and at anything less than best, not as good.
How does that then square with your finding MQA to be a great leap over Hi Res?
Could it then just be the old variable that we know so well - mastering? And MQA just a new bottle for the old red herring of Hi Res?
Any normal Hi res file can be converted to 16/44 to yield the same sound via 16/44 kit. If this can also be done for the MQA files that have moved you to "tears", see what happens when you play these via Sonos.
Userlevel 5
Badge +4
I have found that MQA exceeds HiRes on most files.
I couldn't work out why it often sounded so much better, and started to look into it more, it is not about resolution, it is about encoding the file digitally without loosing out on timing detail, almost looking back at why analogue can sound so good.

I think the soundbites that say "Hi Res quality from a small file" are more confusing that good.

This was the best explanation of why MQA works so well.......


MQA part 1; Why 24 bit 192 kHz audio?
https://www.youtube.com/watch?v=r_wxRGiBoJg

MQA part 2: how does MQA work
https://www.youtube.com/watch?v=T5o6XHVK2HA&t=56s


They are a bit long, but worth a watch.

Remember, Bob Stuart has always said anything above 24/96 is pointless, he changed his mind. Not saying higher res is needed for playback, but for encoding it adds a lot.


http://www.computeraudiophile.com/content/694-comprehensive-q-mqa-s-bob-stuart/



http://www.computeraudiophile.com/content/694-comprehensive-q-mqa-s-bob-stuart/

I am not an engineer, so my eyes glazed over very early with all the incomprehensible jargon. I persisted but I saw no point once I saw the graph that places CD at a lower sound quality capability than an LP. And you have to accept that Stuart has money to make in pushing his view.
If you or anyone is able to write about MQA being distinguished as different in a single variable double blind test of the kind that no one in the world of real science has a quibble with, it would be of interest. The next question then would be that which of the two different sounds are closer to the performance, which is more HiFi. Different does not automatically place it on the side of HigherFi.
That's the thing, MQA cannot be downsampled to standard resolution, Meridian won't allow it. They specifically forbid any of their licensed MQA products from outputting raw digital data. Therefore it is impossible to confirm how much is the higher resolution (science says the answer is none) and how much is the special mastering done by Meridian (science says 100%) via an ABX test. My, how convenient for Meridian is that? :8

What one could do is strip any hypersonics out of the analog MQA output and resample to 16/44.1, but I highly doubt any audiophile would call that a valid test. Though if you look at the MQA specs, the only thing it accomplishes is stripping extra bits from the bit depth and dedicating them to frequencies above 22 KHz.
Therefore it is impossible to confirm how much is the higher resolution (science says the answer is none) and how much is the special mastering done by Meridian (science says 100%) via an ABX test. My, how convenient for Meridian is that? :8

Yes, it is a clever copout. As cover for a little more sophisticated snake oil, it looks like.
To me, the controlled ABX listening test is Occam's razor to be used every time some one puts together graphs and jargon for the next best thing. Based on a very useful question attributed to the late Dudley Harwood, the founder of Harbeth speakers. "That's all very well laddie, but does it sound any different/better?" was his response to any suggested improvement in speaker design. Sound - pun intended - common sense.
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........

Of course, leading people to believe that it is capable of true high end performance, whilst failing to provide any ABX double blind testing to prove it, is equally misleading, surely... And insisting that people prove any claims (e.g. HiRes, MQA) with proper scientific testing, yet letting absurd claims like this go completely unchallenged, must surely be the ultimate in hypocrisy...

Sonos is very good at what it does, at it's price point.... Continually insisting that it's something it isn't can only lead to disappointment.
whilst failing to provide any ABX double blind testing to prove it

What a great line to make a last response to you, for anyone else that chances on this!

I believe that the onus for this lies on those that hear differences, not on those that do not, because ABX testing is used to establish that a difference exists. An ABX test, when the result is positive, is a statistical proof that a difference is audible. That is the main use of ABX testing.

When the result is negative, it is more complex to analyse, and a negative ABX doesn't prove anything. It doesn't prove that there is no difference.

Continually then asking for this to prove no difference between Sonos and High End - whatever that imprecise phrase means - isn't hypocrisy, it is just silly and childish and points to a lack of understanding of ABX testing. Particularly when I have also often said that speaker selection is a subjective matter of preferences between one good and another just as good, best done by listening to it in the kinds of environments that it is designed for, and when it is set up to deliver all of its designed performance. Someone that is disappointed after following that advice isn't anything I lose sleep over.

And I have more than once set out exactly how I did a blind level matched test - not double blind ABX - of two DACs of relevance to me, to see if I hear differences. Saying again what I did there - if I did not hear a difference in this test, it was very unlikely that I would hear it if the full ABX protocol was followed in this case. Did I prove that no difference exists? Of course not, and I did not say so then as I do not say so now. But I believe I have done more than most here that just spout claims to have heard differences that are on the superior side of sound quality.
Continually then asking for this to prove no difference between Sonos and High End....

I'm flexible - I'm happy to take advice on an agreed scientific method to evaluate the situation. You continue to provide no evidence whatsoever that Sonos kit can compete with high-end audio kit (let's cap it at $40k, shall we, for obvious reasons) yet continue to make these misleading statements. Whatever their CEO says in interviews, Sonos know better than to make such ludicrous claims in their advertising, as they would soon be caught out. Do you really think that, if it were even remotely true, that they would fail to capitalize on it?

And I have more than once set out exactly how I did a blind level matched test - not double blind ABX - of two DACs of relevance to me, to see if I hear differences.

Which has no relevance whatsoever when we're discussing whether Sonos can audibly compete with high end kit.
In ABX testing (and double blind testing inn general), the default position (the null hypothesis) is that A & B are indistinguishable from each other. That is the starting point and the assumption that should be made going into the test. Any test which approaches this from a different point of view (e.g. with the assumption that A & B are different) is inherently broken and bogus.

By definition the default position, the null hypothesis, the assumption that A&B are equal, cannot be proven. It can only be disproven. That is why it is chosen as the null hypothesis as we are looking to see if there are significant statistical deviations which show it isn't valid.

Note that ABX tests do not give a black and white, binary result. They give statistical output which can be used to judge how significant the deviation from the null hypothesis is; how likely it is that the null hypothesis has been invalidated.

Of course, in extreme examples (for instance, an ABX comparing an AM radio to a high-end hifi) will give clearly statistical evidence that they are not equal, that the null hypothesis is disproven.

However, that's not the sort of test we are talking about here. We are talking about differences that, if they exist, are extremely subtle and are likely to suffer from a lot of noise and error (statistically speaking).

So in summary:

The default position is that sources are the same. That position is impossible to prove.

Demanding so is unreasonable and unscientific. The onus is on people who claim otherwise to demonstrate a significant statistical deviation from that position.

Or, put another way, "extraordinary claims demand extraordinary proof".

The ball is in your court.

Cheers,

Keith
@Peter, if you are still here! - circling back to topic, this from what Sonos still claims for the Connect:
"CONNECT streams the music you love without loss of fidelity and at full CD-quality bandwidth".
Any comment? Ludicrous claim?:D
By the way, they also say this about the 5 unit:
"Attention obsessive audiophiles and hard-core music lovers. PLAY:5 is your speaker."
I can't speak to that bit because I am not an obsessive audiophile, I have outgrown that phase🆒
I must admit I was concerned that advertising claims about the Connect could be problematic for Sonos with this recent change.

Personally, I think the claims you quote are "marketing speak" and really don't say that much other than the units can play full-rate CD files or streams (i.e. 44.1kHz 16 bit FLAC, WAV, ALAC files). That in itself is clearly a benefit, but it doesn't say anything about the output quality. That's especially so for the Play:5 where there are amps, crossovers, DSP and EQ involved, not to mention the speakers themselves.

I think the only legal concern would be if they used the claims "bit-perfect" or similar, and I don't find any reference to them doing this (or having done this in the past) in their advertising or specs.

Cheers,

Keith
Not only is demanding one prove a negative unreasonable, it is a violation of the rules of logic upon which the entire scientific method is based. Although there are plenty of arguments that prove negatives ("There is no milk in this bowl"), one can never prove a universal negative ("There is no milk in any bowl, anywhere"). Similarly, one cannot prove there are no differences between audio equipment, anywhere.

Kumar is logically correct to say he personally found no differences in a semi-rigid scientific test of two DACs, and then use this as evidence in a discussion (it is certainly more evidence than anyone on the other side has ever given). However, asking him to prove that his findings are a universal truth violates logic, just as asking someone who sees no milk in his bowl to prove there is no milk in any bowls, anywhere, is a violation of logic.

The burden is upon those who claim the positive, i.e there are differences between audio equipment, or there is milk in a bowl somewhere. Some of these positive claims are easy to prove (just pour milk in a bowl , , , voila! You have proof), some are hard, and require specialized testing methods which adhere to the scientific method before proof will be accepted (ABX testing). But whatever the proof, the burden is upon those who make the claim that differences exist, not those who claim they do not. The null hypothesis never needs proving, because it simply cannot be proven.

The burden is upon those who claim the positive, i.e there are differences between audio equipment,

Even funnier is that I accept that there are audible differences - where it comes to end products like speakers/active speakers! What is being found objectionable is my contention that something like a 5 pair + Sub can hold its own against "high end" audio kit in a room that isn't too large for it. Which to me just sounds like the usual elitist audiophile hot air with no substance and nothing to say in support except parroting ABX without either understanding what is being said or what ABX achieves.

Further, I have also said there there could be a preference for the sound for a specific "high end" kit, but it is also likely to be otherwise, in favour of Sonos. Price/Brand is irrelevant here if its knowledge is made to disappear so as to eliminate confirmation/expectation bias, so as to confound the many that mindlessly equate these with high end audio.

Obviously marketing speak need not be taken at face value; although saying "no loss of fidelity" as Sonos has = a claim on output quality where Connect is concerned? My reason to quote the marketing was just to make the point that to say that Sonos makes no marketing claims to compete against audiophile kit is a false statement.

Enough already!:D
Yes Kumar, you've been explicit in your claims, both that speakers have obvious audible differences and in the pure subjectivity of your observations about quality differences between Sonos and "audiophile" components. It is too bad that in these discussions, a valid scientific concept like ABX testing is used as a cudgel against those who aren't making any universal objective claims requiring an ABX test. The irony is, when an ABX test could supply actual proof of a claim, like DACs sound different, or Hires is better than CD even when sourced from the same master, ABX testing is never cited, or it is somehow discredited as being fallible, or not telling the whole story (and of course, no one ever mentions a scientifically valid alternative to this fallible and/or incomplete testing method).
Circling back again to topic, another thread recently had me flip my 2011 Connect over to see zp90 written on its base. Presumably this is still bit perfect? No way I can tell because it is analog wired via 2 channel amp to my external speakers where any difference will never be audible. But it is all very puzzling - given that all my other kit is Connect Amps and play units, does this mean that the zp90 is less capable on the volume normalisation front that those items? A mystery, this bit perfect issue, even more so because the normalisation itself isn't a big perceived benefit as far I can tell.
Not sure what models were specifically affected. Sonos would have to answer that.

As to your trying to get this thread back on topic; I have been chuckling for the past couple of days at the outrage directed at me for "derailing" this thread. Outrage which came from a poster who ignored everything about the Connect being bit-perfect and instead shot us off the rails into Hires/MQA land!
Lol. AFAIK, Peter is one forgiving Aussie!
... does this mean that the zp90 is less capable on the volume normalisation front that those items? A mystery, this bit perfect issue, even more so because the normalisation itself isn't a big perceived benefit as far I can tell.

That makes some sense. Presumably newer unit have different components and more processing/DSP power.

Whilst you may not perceive it to be a benefit, I have to assume that Sonos consider it to be beneficial in some way (I'm sure you realise this) otherwise they wouldn't have added it.

Certainly there have been long running discussions on volume normalization over the years and it's an area many of us consider Sonos to be weak on. Several years ago they even made an aborted attempt to add improved Replaygain support. One of the challenges that Sonos (and others) have had with normalisation is the hard limit at the top end.

Volume normalisation schemes are based on average levels and comprise a gain offset that should be applied across the whole track. Without compression, that can result in peaks hitting the brick wall if the volume control is near the top of it's setting. Fixed volume setting gives the biggest issue, because that is equivalent to maximum volume. Previously Sonos have treated fixed as a special case and not applied normalisation in that case.

I can see the benefit to having both normalisation and unadulterated bits. Obviously the two are mutually exclusive, which is why I think it should be a per-player setting.

Cheers,

Keith
My recollection was that Sonos scaled down a positive ReplayGain based on the amount of volume headroom below 100%. Clearly this meant that at Fixed Volume/100% the gain would be reduced to zero.

In theory this should have meant that clipping was always avoided, without needing to introduce brick wall compression.
My recollection was that Sonos scaled down a positive ReplayGain based on the amount of volume headroom below 100%. Clearly this meant that at Fixed Volume/100% the gain would be reduced to zero.

In theory this should have meant that clipping was always avoided, without needing to introduce brick wall compression.


Ah yes, that's right. Well remembered.

Cheers,

Keith