Question

Connect no longer bit-perfect?

Forum|Forum|10 years ago
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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Peter McAuthor

I'm not even sure he "allowed himself to be directly quoted". I have seen so many examples of journalists misquoting scientists. Mostly we try and approve the final copy, but this is not always possible. There is no evidence that the inaccuracy was found and allowed through. When you say "cleverly done", this implies a deliberate act, and there is no evidence of this. Also, the wrong quote can only be admitted when it is observed. Finally, the primary source is the paper. No such statement appears in the paper. So I would say, on appeal, Not Out!

"The presence of those seeking the truth is infinitely to be preferred to those who think they've found it" - Terry Pratchett

K

Kumar

Mostly we try and approve the final copy, but this is not always possible. There is no evidence that the inaccuracy was found and allowed through. When you say "cleverly done", this implies a deliberate act, and there is no evidence of this. Also, the wrong quote can only be admitted when it is observed. Finally, the primary source is the paper. No such statement appears in the paper. So I would say, on appeal, Not Out!

Oh come now Peter, aren't you stretching things a tad?
The author of the report said this himself on the other thread on this site:
"Press releases are put forward by organisations with the aim of trying to get the press to cover their story, and as such are a combination of spin, marketing, opinion and fact. In this case, it was written by a press officer at my university, and then AES issued another similar one." I have cut/pasted, no spin!

This isn't just a random release on the net that the author can be excused for being ignorant about, but is from the author's organisation! You really think that the author, if he did not make these fully fleshed out and attributed in quotes to him statements, also remained ignorant of what his own organisation is saying what he said, and that too in italicised quotes? In this day and age? And then also continued to remain ignorant of the AES doing the same thing? Knowing as he says he does that press releases are used for spin? Is it then that his organisation is the one doing the clever shill and our author is just the naive scientist labouring honestly in the lab, not knowing what his evil superiors are doing to spin his report?! Give me a break!

I am not saying this isn't possible, just making my assessment of the probabilities. And why can I not say that if he really did not know how his organisation is spinning his report, that is in itself an indictment of sorts?

Peter McAuthor

...a combination of spin, marketing, opinion and fact

None of those imply stating something that is incorrect. My organization also puts out press releases with the same four qualities. This is done by science journalists after talking to the authors of the work. The copy is not always checked by the authors before release due to press deadlines. But I strongly believe that where at all possible a press release should always be checked by the author of the work, and this is one lesson to be learned here. Even after checking, I know of cases where the sub-editor of a newspaper chose headlines or picture captions that were just plain wrong. This occurred after any chance of checking.

On the flip side, there is also an obligation on the part of a reader of internet information to check the primary source before getting too carried away by what they have read. In this case it is the published paper itself. The press release contained a link to the paper, which is freely available. Anyone who is mislead by the press release has not done their due diligence and checked the primary source.

So, to summarize, both sides of the argument need to get their checking act together 🙂

"The presence of those seeking the truth is infinitely to be preferred to those who think they've found it" - Terry Pratchett

K

Kumar

Anyone who is mislead by the press release has not done their due diligence and checked the primary source.

If all that bought into the benefits of Hi res audio and then proclaimed its benefits in audiophile circles and internet forums had the bent of mind to do the kind of diligence you refer to, and to exert efforts to read and understand primary papers, would they exist even in the small numbers they do today?!:D

At the end of the day, people will believe what they want to believe. Fortunately in this case, not enough believe in Hi Res to the extent that Sonos see them as a market of interest. Long may that market dynamic not change!

jgatie

I never called anyone a liar.

Mr. Reiss is lying in his PR statement.

I stand by my accusation. Dr. Reiss is lying in his PR statement.

...in reality a lie, attributed directly to you.

And not once did I say Mr. Reiss is a liar. Only that his statement (if in fact, it was his statement) with regards to the PR release for his study was a lie.

I stand by that assessment.

K

Kumar

Digressing completely, the American meaning of the word bigot, from the Webster dictionary:
"a person who is obstinately or intolerantly devoted to his or her own opinions and prejudices; especially : one who regards or treats the members of a group (as a racial or ethnic group) with hatred and intolerance"
and the English one, from the Oxford English dictionary:
"A person who is intolerant towards those holding different opinions"

Presumably which side of the Atlantic one is from would decide what meaning gets conveyed by the word.

I would not be comfortable being called either kind of a person, but it seems that the word would sit a little more easily in the UK.

Bit perfect means the same on both sides.;)

G

gizze

Enthusiast II

Bigot can mean the same in the UK too, but we are talking about hifi, not races or cultures.
I presumed that people were intelligent enough to understand the context of the discussion we were having.

"a person who is obstinately or intolerantly devoted to his or her own opinions and prejudices; especially : one who regards or treats the members of a group (as in those who believe in Hi Res) with hatred and intolerance" 😃

Maybe I should have said 'insular' instead, or 'snob' but then most people don't understand the word 'snob' many think it means stuck up or posh.

I think the problem maybe that Bigot has been used so much in the last few months with what has been happening with Brexit and Trump that many maybe only know it from hearing it in a derogatory way.
It is the same when you call someone ignorant, so many people get all annoyed and say things like "Don't call me stupid!". Which is always kind of ironic.

jgatie

There is only one person here showing a degree of intolerance that rises to a level of calling for people to shut up and stop posting their opinion.

K

Kumar

I think the problem maybe that Bigot has been used so much in the last few months with what has been happening with Brexit and Trump that many maybe only know it from hearing it in a derogatory way.

I disagree; accusing someone of bigotry has been a serious thing for a long time now and I am saying this with confidence even as someone whose mother tongue isn't English. A lot more people may be throwing the word around these days, but an undeserved/unproved accusation of bigotry would be derogatory in my book for decades now.

A

amun

Do you start to understand now the double standard being applied here?

No, I really don't think that they do....

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