# Jitter and DSPs..?



## jonlanghoff (Nov 25, 2015)

Hi forum,


In my setup I've got a notoriously jitter-prone unit (a standard Sonos Connect) supplying signal via digital coax to my DSP (a miniDSP nanoDIGI), and then on via digital coax to my DAC.

My question is:
Which effect does the DSP have on the jitter coming from the Sonos unit?
- Does it just propagate the jitter?
- Does it worsen the jitter?
- Does it even remove the jitter? (perhaps due to the DSP being a state machine)

My reason for asking is that if the jitter proceeds to be a problem (regardless of the DSP being in the signal chain) I'd consider buying either a Sonos mod (Cullen/Volk/W4S/whatever) or a re-clocker to put between the Sonos and the DSP...

Any other thoughts in general regarding the issue?


B.R. Jon


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## AudiocRaver (Jun 6, 2012)

jonlanghoff said:


> Hi forum,
> 
> 
> In my setup I've got a notoriously jitter-prone unit (a standard Sonos Connect) supplying signal via digital coax to my DSP (a miniDSP nanoDIGI), and then on via digital coax to my DAC.
> ...


Is the jitter a problem? Does it need improvement?

It is hard to tell without a good AB comparison.

The DSP will reclock, _probably_ an improvement. Whether or not it gives improvement, and how much, will depend on a lot of factors, including the design of the DSP, including whether it was bad in the first place.

Notoriously jitter prone? Is is a real audible problem or some nonsense you have been told or read, something to worry about? Just curious.


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## lcaillo (May 2, 2006)

Ditto those questions. I was thinking in the same direction and also wondering why the big concern.

I would NOT assume that inserting another clocking device in the path to be a solution. If I had doubts about the source I would make sure that the destination device handled the problem itself. As Wayne says, most DSP devices will establish their own clock. How they handle source errors likely depends on the nature of the error. Minor random errors will likely be corrected but larger scale biases might be a problem for any secondary clock system.


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## jonlanghoff (Nov 25, 2015)

AudiocRaver said:


> Is the jitter a problem? Does it need improvement?
> It is hard to tell without a good AB comparison.


I cannot tell you that I know what the jitter from the Sonos (or any kind of jitter) sounds like.



AudiocRaver said:


> The DSP will reclock, _probably_ an improvement. Whether or not it gives improvement, and how much, will depend on a lot of factors, including the design of the DSP, including whether it was bad in the first place.


I have a Primare I22 amp with a built-in DAC module and it says in the specs that it reclocks the signal when using the USB-connection, but I'm using coax. Perhaps it does so too when using the coax, but it doesn't say explicitly anywhere.



AudiocRaver said:


> Notoriously jitter prone? Is is a real audible problem or some nonsense you have been told or read, something to worry about? Just curious.


The latter. It's solely based on positive reviews of Sonos mods and reclockers, but perhaps they're all full of B and S? - It's definitely an option!
Another option is that the mods and separate reclockers have other positive effects than just removing jitter. Any thoughts?


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## AudiocRaver (Jun 6, 2012)

jonlanghoff said:


> I cannot tell you that I know what the jitter from the Sonos (or any kind of jitter) sounds like.


With a sine wave input, sidebands are generated, sounding very harsh, much more so than harmonic distortion.

Look for a test track with lots of clean cymbals or high bells, xylophone, triangle, etc. Sideband distortion will cause a "splatter" of "hash" to be added to those sounds. Also, the distortion would not get worse with a higher signal level like it usually does with harmonic distortion. A lower signal level out of the source (before the digital link in question) followed by boost afterward, would - I believe - increase the distortion level of that digital link, IF it is a problem at all.



> I have a Primare I22 amp with a built-in DAC module and it says in the specs that it reclocks the signal when using the USB-connection, but I'm using coax. Perhaps it does so too when using the coax, but it doesn't say explicitly anywhere.


The D to A conversion would involve reclocking regardless of digital input type.



> The latter. It's solely based on positive reviews of Sonos mods and reclockers, but perhaps they're all full of B and S? - It's definitely an option!
> Another option is that the mods and separate reclockers have other positive effects than just removing jitter. Any thoughts?


I do not know what those _other positive effects_ might be, more than likely there are claims that amount to unprovable hype. Even positive reviews are not necessarily trustworthy. A review with measurements of sideband distortion before and after would be useful.


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## Ethan Winer (Jul 21, 2006)

jonlanghoff said:


> I cannot tell you that I know what the jitter from the Sonos (or any kind of jitter) sounds like.


Right, nobody can tell you what jitter sounds like because it's so soft that it's never even audible. The _only_ way you could know what jitter sounds like is if you have a "jitter generating box" with a knob you can turn to know how much is needed before you can hear it. Nobody has one of those boxes, so nobody can tell from direct experience what jitter sounds like. To keep this in perspective, the attached graphic shows the frequency spectrum of jitter at 2 ns. Notice how soft the artifacts are, averaging around -115 dB. For reference, jitter for most types of digital audio devices is typically under 0.5 nanoseconds, which is only 1/4 as loud.

If you'd like to hear how to relate dB levels with artifact audibility, this short article includes Wave file examples you can download:

Artifact Audibility Report

The noise used in these examples isn't exactly the same as jitter, but it's close enough for the purpose of learning at what levels jitter and other artifacts become audible.

--Ethan


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## jonlanghoff (Nov 25, 2015)

AudiocRaver said:


> I do not know what those _other positive effects_ might be, more than likely there are claims that amount to unprovable hype. Even positive reviews are not necessarily trustworthy. A review with measurements of sideband distortion before and after would be useful.


I honestly do not know, and I'm usually prette allergic to snakeoil, but do you also suggest that a $100 CD player *sounds* just as good as a $1,000 or $10,000 CD player?


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## AudiocRaver (Jun 6, 2012)

jonlanghoff said:


> I honestly do not know, and I'm usually prette allergic to snakeoil, but do you also suggest that a $100 CD player *sounds* just as good as a $1,000 or $10,000 CD player?



Yes
No
Possibly
Probably Not
It Depends

There, is that vague enough?

Kidding, of course. What I meant to say is this: There are a lot of ways to spin a performance claim.

Some are true and correct and directly measurable or provable via careful and repeatable listening tests;
Some are based in fact with some stretch or exaggeration that negates it;
Some are based in fact by some logical string of reasoning but with big assumptions and holes in that logic that negate it, and;
Some are simply fabrications based on imagination or misunderstanding or - sadly - dishonesty.
I am not directly suggesting any one of the above, simply suggesting that it is common in Audio gear advertising for "untruth" or "stretches of the truth" to occur, and that some of the claims that have gotten you concerned MIGHT not be based in fact.


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## Ethan Winer (Jul 21, 2006)

jonlanghoff said:


> do you also suggest that a $100 CD player *sounds* just as good as a $1,000 or $10,000 CD player?


Oh geez, I'll come right out and say it: Yes, there's no reason a $100 CD player can't be audibly transparent. :grin2:

If a device is audibly transparent, that means it doesn't affect the sound at all. So it has no "color" or "character" or sound of its own. And if it has no sound, then it's indistinguishable from any other transparent device. Lots of audio gear is transparent these days! The real gremlins are, as always, loudspeakers and room acoustics.

--Ethan


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## jonlanghoff (Nov 25, 2015)

AudiocRaver said:


> With a sine wave input, sidebands are generated, sounding very harsh, much more so than harmonic distortion.
> 
> Look for a test track with lots of clean cymbals or high bells, xylophone, triangle, etc. Sideband distortion will cause a "splatter" of "hash" to be added to those sounds. Also, the distortion would not get worse with a higher signal level like it usually does with harmonic distortion. A lower signal level out of the source (before the digital link in question) followed by boost afterward, would - I believe - increase the distortion level of that digital link, IF it is a problem at all.


If anything, I have noticed that S-sounds from vocals sometimes can become harsh and hissy when the volume is turned up high. Does this sound like something that could be caused by jitter?



AudiocRaver said:


> The D to A conversion would involve reclocking regardless of digital input type.


If reclocking is the way to solve jitter (which is what I understand from reading about it all night yesterday :grin2 do you then suggest that jitter should NEVER be an issue then? - If reclocking always occur inside any DAC anyways..?



AudiocRaver said:


> I do not know what those _other positive effects_ might be, more than likely there are claims that amount to unprovable hype. Even positive reviews are not necessarily trustworthy. A review with measurements of sideband distortion before and after would be useful.


I definitely agree! I would love to see a review where measurement results from a jittery system (e.g. Sonos Connect -> DAC -> Amp -> Speakers) were compared to the same system with a reclocker inserted into the chain or with the Sonos Connect replaced with a modded Sonos Connect.





Ethan Winer said:


> Right, nobody can tell you what jitter sounds like because it's so soft that it's never even audible. The _only_ way you could know what jitter sounds like is if you have a "jitter generating box" with a knob you can turn to know how much is needed before you can hear it. Nobody has one of those boxes, so nobody can tell from direct experience what jitter sounds like. To keep this in perspective, the attached graphic shows the frequency spectrum of jitter at 2 ns. Notice how soft the artifacts are, averaging around -115 dB. For reference, jitter for most types of digital audio devices is typically under 0.5 nanoseconds, which is only 1/4 as loud.


I also suspect that the effect of jitter will usually be very small relative to the "main signal", but this of course doesn't mean that it can't have an audible effect. Many people claim to be able to tell the difference from jittery and non-jittery systems, but admittedly I *do* miss some hard science with double-blind studies etc.!





AudiocRaver said:


> Yes
> No
> Possibly
> Probably Not
> ...


I'm not very concerned with the promises of the manufacturers, cause I have the same view on specs etc. as you do, but tests/reviews are interesting to me and I'm surprised to see how many professional sites/publications and regular users claim obvious improvements in sound when using, for example, this reclocker in their systems: https://wyred4sound.com/products/digital-converters/remedy-reclocker
Mass hysteria? Placebo? Straight up dishonesty?





Ethan Winer said:


> Oh geez, I'll come right out and say it: Yes, there's no reason a $100 CD player can't be audibly transparent.
> 
> If a device is audibly transparent, that means it doesn't affect the sound at all. So it has no "color" or "character" or sound of its own. And if it has no sound, then it's indistinguishable from any other transparent device. Lots of audio gear is transparent these days! The real gremlins are, as always, loudspeakers and room acoustics.


My *intuition* also tells me that it should be possible to have a cheap CD player sounding "perfect" as it lives in the digital domain. - But do you then suggest that the only difference between a good, cheap CD player and a super expensive one is colouration (and of course built-quality, design, brand name)? Are people throwing money out the window when they buy a $10k CD player, in terms of audio quality?


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## AudiocRaver (Jun 6, 2012)

Ethan Winer said:


> Oh geez, I'll come right out and say it: Yes, there's no reason a $100 CD player can't be audibly transparent. :grin2:
> 
> If a device is audibly transparent, that means it doesn't affect the sound at all. So it has no "color" or "character" or sound of its own. And if it has no sound, then it's indistinguishable from any other transparent device. Lots of audio gear is transparent these days! The real gremlins are, as always, loudspeakers and room acoustics.
> 
> --Ethan


Ethan is a little more decisive than I am. Of course a $100 CD player CAN sound as good as a $1000 or $10000 CD player. Most probably do. But not necessarily!



jonlanghoff said:


> If anything, I have noticed that S-sounds from vocals sometimes can become harsh and hissy when the volume is turned up high. Does this sound like something that could be caused by jitter?


Possibly, although distortion from jitter would not increase with volume like harmonic distortion does. In fact, if I understand correctly, distortion from jitter ends up acting more like an addition to the noise floor, only more objectionable. IF it is at a level where it can be heard at all, it would seem to be worse with a lower volume level running through the digital link in question - giving a lower signal-to-noise ratio - followed by gain to re-boost the signal. That is a bad way to run a system, but a way to look for potential noise & jitter problems.

The BEST way is to measure. With Room EQ Wizard, run a sine wave through that part of your system and look at the noise floor with the REW's Real Time Analyzer (RTA). Jitter will show as little spikes on either side of the sine wave's big spike. Bet you it will be clean!



> If reclocking is the way to solve jitter (which is what I understand from reading about it all night yesterday :grin2 do you then suggest that jitter should NEVER be an issue then? - If reclocking always occur inside any DAC anyways..?


Any stage of well-designed reclocking (ie a DAC) will PROBABLY improve it, if it needs improving at all.



> I definitely agree! I would love to see a review where measurement results from a jittery system (e.g. Sonos Connect -> DAC -> Amp -> Speakers) were compared to the same system with a reclocker inserted into the chain or with the Sonos Connect replaced with a modded Sonos Connect.


That would be an interesting test.



> Many people claim to be able to tell the difference from jittery and non-jittery systems...


I am sure. A few probably actually can, under the right conditions.



> I'm not very concerned with the promises of the manufacturers, cause I have the same view on specs etc. as you do, but tests/reviews are interesting to me and I'm surprised to see how many professional sites/publications and regular users claim obvious improvements in sound when using, for example, this reclocker in their systems: https://wyred4sound.com/products/digital-converters/remedy-reclocker
> Mass hysteria? Placebo? Straight up dishonesty?


Hard to say. Most "testimony" from general users is suspect.



> My *intuition* also tells me that it should be possible to have a cheap CD player sounding "perfect" as it lives in the digital domain. - But do you then suggest that the only difference between a good, cheap CD player and a super expensive one is colouration (and of course built-quality, design, brand name)? Are people throwing money out the window when they buy a $10k CD player, in terms of audio quality?


Probably. Not necessarily.


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## jonlanghoff (Nov 25, 2015)

Thanks for taking time to respond to my ramblings! 

Great advice with the REW testing - I'll definitely try that when I get home from work - but I have, though, read that sine waves shouldn't expose jitter in the same way as impulses do. I'll try messing around with some measurements and see if I can reproduce something interesting!

B.R.


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## Ethan Winer (Jul 21, 2006)

jonlanghoff said:


> If anything, I have noticed that S-sounds from vocals sometimes can become harsh and hissy when the volume is turned up high. Does this sound like something that could be caused by jitter?


No, that's called _sibilance_, and it's a type of distortion vaguely related to popping P's because both can occur when someone is too close to the microphone.



> I would love to see a review where measurement results from a jittery system (e.g. Sonos Connect -> DAC -> Amp -> Speakers) were compared to the same system with a reclocker inserted into the chain or with the Sonos Connect replaced with a modded Sonos Connect.


I don't know how much clearer I can be: Jitter is never _EVER_ a problem. It's a bogey man invented by people that sell gear to get you to buy "newer better" gear to replace what you already have, and parroted by clueless magazine reviewers. I can't hear jitter. You can't hear jitter. _Nobody_ can hear jitter. Only highly sensitive test gear can detect it. It might as well not even exist.



> But do you then suggest that the only difference between a good, cheap CD player and a super expensive one is colouration (and of course built-quality, design, brand name)? Are people throwing money out the window when they buy a $10k CD player, in terms of audio quality?


Only four parameters are needed to define audio fidelity: Frequency response, distortion, noise, and time-based errors. If you're serious about learning how this all fits together, and how audio really works, my two AES Workshop videos explain it in great detail:










So yes, "coloration" in the form of response errors or distortion etc are the only difference between one CD player (or amp or preamp) and another.

--Ethan


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## Ethan Winer (Jul 21, 2006)

AudiocRaver said:


> Of course a $100 CD player CAN sound as good as a $1000 or $10000 CD player. Most probably do. But not necessarily!


Sure, probably but not always. The opposite happens too, surprisingly often: A $10,000 device can be measurably and subjectively worse than a budget consumer-grade device. I've seen $5,000 "audiophile" tube amps with more than 5 percent distortion.



> distortion from jitter would not increase with volume like harmonic distortion does.


Of course it does. Jitter manifests as FM (Frequency Modulation) side-bands, so its level is directly related to the level of the main audio.



> Most "testimony" from general users is suspect.


No kidding. :surprise:

--Ethan


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## AudiocRaver (Jun 6, 2012)

Ethan Winer said:


> Sure, probably but not always. The opposite happens too, surprisingly often: A $10,000 device can be measurably and subjectively worse than a budget consumer-grade device. I've seen $5,000 "audiophile" tube amps with more than 5 percent distortion.


Ethan, thanks for joining the dialogue. No argument here, bottom line is that price and sonic transparency often do not correlate very well with audio gear. I would like to believe that it often/usually does, but that is just the hope junkie in me, which is oft disappointed.



> Of course it does. Jitter manifests as FM (Frequency Modulation) side-bands, so its level is directly related to the level of the main audio.


Silly me, I was just not thinking straight on this one. Of course Ethan's answer is correct. Pardon my temporary lapse of sanity.


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## AudiocRaver (Jun 6, 2012)

Ethan Winer said:


> I don't know how much clearer I can be: Jitter is never _EVER_ a problem. It's a bogey man invented by people that sell gear to get you to buy "newer better" gear to replace what you already have, and parroted by clueless magazine reviewers. I can't hear jitter. You can't hear jitter. _Nobody_ can hear jitter. Only highly sensitive test gear can detect it. It might as well not even exist.


I personally hesitate to use the _never EVER_ claim for anything. _Never EVER_ is a very long time. As Ethan himself has pointed out, jitter can be purposely produced in audible amounts to demonstrate what it sounds like. In audio equipment designed by competent humans and intended to perform well, it is probably pretty hard to come by. But _never EVER?_ Careful, Ethan!:wink2:


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## Ethan Winer (Jul 21, 2006)

LOL, okay, sure, how about "virtually never?" :grin2:


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## jonlanghoff (Nov 25, 2015)

First of all, thank you Ethan (I bet you've been discussing this about a million times before, so kudos for taking it up again!) and everyone else for chiming in.

I'm definitely more in the propellerhead camp than in the "audiophile true believer" camp (as would I think most people currently participating in this thread are), but I also recognize that even though measurements perhaps only show small differences between jitter-prone and low jitter equipment, there could(!) still be discernibles difference under certain circumstances - and I would think that it should be possible to sort out with double blinded testing, although I acknowledge that it might be hard to conduct correctly and to "everyone's" satisfaction.



Case: Many people claim that they can tell a difference between the standard Sonos Connect and (e.g.) a W4S-modded Sonos Connect. This is a real-life example (eliminating the need for a "jitter machine" or other artificial circumstances) where many users and reviewers claim OBVIOUS improvements.

1) Put together a panel consisting of some people with confirmation bias "for" the benefit of using low jitter devices, some people with bias against it and some neutral laymen, and let a facilitator run the test with a minimum of communication with the participants plus what-ever best practices else exist when doing this kind of testing.

2) Put together a setup with the two players in question connected to the same multiple-input DAC. Ensure that widely claimed "neutral/transparent" cables and equipment are used, of course. Ensure near-optimal room acoustics... wink, Ethan! 

3) Perform listening tests that supposedly should be optimal for exposing jitter. Let the audiophiles decide! - It could be sine waves, impulses, instrument samples, music clips of various lengths, what-ever.



If the above experiment has already been conducted and its results are available, please forgive me AND SHOW THEM TO ME IMMEDIATELY, because God knows I'm tired of looking for them as well as surprised of their absence..!

What do you guys think?



EDIT: I know that the burden of proof (of showing that jitter in audio equipment can be heard and is perceptibly degrading to the sound) is always on the claimant, being the audiophiles, but I see clarification of the issue as being in the interest of both "camps", and as such it could just as well be "us" who take the initiative! - Also, it would lend more credence than just pointing to measurements showing very small effects of jitter, as this isn't the point of dispute - the audiobility is.


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## Ethan Winer (Jul 21, 2006)

I don't know if your specific proposed test has ever been done, but there have absolutely been blind tests where people listened so the researchers could tell how much jitter you need before it's audible. Here's one that concluded the threshold is around 10 ns, which is 20 times more than is typical:

http://www.aes.org/e-lib/browse.cfm?elib=8354

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

From the conclusion:

"The effect of clock jitter in the digital interface was studied extensively. Measurements of the jitter spectrum of numerous digital audio sources, primarily DVD players, were conducted. A wide range of performance was found. The jitter spectrum of a typical source can be characterized as a white noise floor with one or many sinusoidal jitter components with a magnitude in the range of 10 ps to 10 ns rms. The effect of jitter induced in the interface was studied and found not to be a significant factor for short interconnection runs likely to found in a domestic environment. Several DACs and their DIRs were measured in order to characterize the sensitivity to distortion induced by jitter. These results were compared to each other and to results derived from simulations. Most DACs were found to be similar to each other and to the simulation in terms of susceptibility to jitter-induced distortion. That distortion is approximately -107+201og(F)+201og(J) dBr for sine wave signals at F kHz with J ns rms of clock jitter.

Up-Down threshold and AB comparison listening tests were conducted to determine the threshold of audibility for jitter-induced distortion. The threshold of audibility for pure tones was found to be about 10 ns rms at 20 kHz and higher at lower frequencies. For nearly all program material no audible degradation was heard for any amount of jitter added below the level at which the DIR lost lock. Certain program material was found in which an audible degradation due to jitter was heard. The threshold of audibility for these programs was generally found to be in the range of 30 ns rms to 300 ns rms for sinusoidal jitter. Finally, the audible degradation was found to correspond to measurable changes in the spectrum of the program material."


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## jonlanghoff (Nov 25, 2015)

Thanks a lot for the excerpt of the study, which I guess pretty much dismisses that jitter can be "perceived" - which was clearly the aim of the study to clarify, but I still have some stuff that I would like to look into:

1) Am I right in assuming that the AB tests were made by comparing one DVD player versus another, and then seeing if the participants could point out the most jittery one of the two? - In this case, could the test results be skewed by other factors than just the measured amount of jitter that could make the participants prefer one over the other??

2) I've read claims that the effects of jitter manifest in the form of listening fatigue, and in this case I guess that "long term" testing should be made to expose this properly. Do you know of any studies that explore the claims about listening fatigue?


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## FargateOne (Mar 3, 2015)

Very interesting discussion.
Blind tests should be tried with a panel of "subjective audiophiles magazine revewers" and "objective scientists" maybe there will be surprises in both camp , isn't it?


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## Ethan Winer (Jul 21, 2006)

jonlanghoff said:


> 1) Am I right in assuming that the AB tests were made by comparing one DVD player versus another, and then seeing if the participants could point out the most jittery one of the two? - In this case, could the test results be skewed by other factors than just the measured amount of jitter that could make the participants prefer one over the other??


I honestly don't know, and I'm too lazy to read it all again. :|



> 2) I've read claims that the effects of jitter manifest in the form of listening fatigue, and in this case I guess that "long term" testing should be made to expose this properly. Do you know of any studies that explore the claims about listening fatigue?


I can tell you for certain that claims like that are _always_ nonsense. Years ago some people claimed that digital music would give you a headache. I remember similar silliness in the 1960s about some types of rock 'n' roll. As FargateOne suggested, the only way to test such claims is with a blind test, and every time that's done the claims are disproved.

--Ethan


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## willis7469 (Jan 31, 2014)

I've heard some pretty bad mp3's that gave me a headache in less than a few minutes. These were "supposed" to be high quality rips, so my expectations were as such.(not blind testing but I was tempered for a good sound). I've always assumed this to be from excessive compression. Cymbals sound like someone squishing a plastic bag, and the music was very flat overall. Watching/listening to music on Dish network could also be fatiguing, but mostly at elevated volume. At any volume you can put your ear next to a tweeter (during dish network) and it sounds like a swishorlyish kind of sound. Drives me nuts! Not sure if these observations are relevant but I thought I'd share. 


Sent from my iPhone using Tapatalk


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## AudiocRaver (Jun 6, 2012)

willis7469 said:


> I've heard some pretty bad mp3's that gave me a headache in less than a few minutes. These were "supposed" to be high quality rips, so my expectations were as such.(not blind testing but I was tempered for a good sound). I've always assumed this to be from excessive compression. Cymbals sound like someone squishing a plastic bag, and the music was very flat overall. Watching/listening to music on Dish network could also be fatiguing, but mostly at elevated volume. At any volume you can put your ear next to a tweeter (during dish network) and it sounds like a swishorlyish kind of sound. Drives me nuts! Not sure if these observations are relevant but I thought I'd share.
> 
> Sent from my iPhone using Tapatalk


I have not heard of such effects giving headaches, but I do not doubt you a bit. They (lossy compression and noise) can sure mess with your noise floor.


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## willis7469 (Jan 31, 2014)

AudiocRaver said:


> I have not heard of such effects giving headaches, but I do not doubt you a bit. They (lossy compression and noise) can sure mess with your noise floor.



I should clarify. It didn't start as a headache. At a normal listening level (-25 or -20) it sounded like it was at 120db, and hurt my ears in the same way as being super loud/distorted. The headache followed shortly after. 


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## Lumen (May 17, 2014)

Ethan Winer said:


> I can tell you for certain that claims like that are _always_ nonsense. Years ago some people claimed that digital music would give you a headache. I remember similar silliness in the 1960s about some types of rock 'n' roll.


Another audiophile myth dispelled!
-- Getting my head on straight :smile:


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## Ethan Winer (Jul 21, 2006)

willis7469 said:


> I've heard some pretty bad mp3's that gave me a headache in less than a few minutes ... I've always assumed this to be from excessive compression. Cymbals sound like someone squishing a plastic bag, and the music was very flat overall.


There are two types of "compression" for audio, and neither automatically sounds bad or gives you a headache. Volume compression sounds fatiguing after a while, and is the basis of the "loudness wars" we hear about. Data compression also sounds bad, at least at low bit-rates by adding a "swishy swirly" sound to music. But once you get up to a reasonably high bit-rate (192 kbps) you can barely notice the compression if you can even tell at all on most types of music.

--Ethan


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## willis7469 (Jan 31, 2014)

Ethan, I agree. Volume compression doesn't bother me in the headache kind of way, but it is irritating when light cymbal work is just as loud as a singer belting away. This I've gotten used to. It's the crunchy low bit rate stuff that hurts. Lol. It does seem though, this has become less and less. I also understand why satellite providers have to go to the lengths they do. I'm sure one day it will not be so. 


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## Ethan Winer (Jul 21, 2006)

Yes, disk space and bandwidth keep getting cheaper, so severe lossy compression will only be less needed in the future. Though I'm not sure if satellite hardware is so easy to update. :nerd:

--Ethan


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## Savjac (Apr 17, 2008)

I have experienced jitter many times, especially when I have too much caffeine or I am in trouble at home.:wink2:


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## willis7469 (Jan 31, 2014)

The 2 worst kind. Yikes!


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## jonlanghoff (Nov 25, 2015)

Hi again guys,



My curiosity has led me to the point where I've actually bought a modded device in order to compare it directly to my out-of-the box Sonos Connect. The modded device is a 2009 Sonos ZP90 which has been modded by Dr. Gert Volk in 2010. The two players are hooked up to each their own little DAC (FiiO D03k Taishan) and then on to my amp (Primare I22).

The first tests I've done are some very simple tone test:

400 hz
https://www.dropbox.com/s/d5xacduvxfbndkx/400hz.m4a?dl=0

1.000 hz
https://www.dropbox.com/s/zxgvhth6z550r5k/1000hz.m4a?dl=0

4.000 hz
https://www.dropbox.com/s/hwo8v3r41123hwz/4000hz.m4a?dl=0

10.000 hz
https://www.dropbox.com/s/lrqufj9q6w3aadh/10000hz.m4a?dl=0

To my surprise, there actually is a discernible difference between the two players' outputs on the 1 khz and 10 khz sample.

I've double checked the results by switching around cables and using different inputs on the amp as well, but the results are the same. Risking to be lumbed in with the audiophile crowd, I think I'd discribe the first of the players (which is the standard Connect) to be a little "metallic", especially on the 1 khz sample.



I wonder why it's only possible to hear a difference on those two samples, while not on the 400 and 4.000 hz ones..?

Also, in general, what are your thought of the above sound bites?


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## Ethan Winer (Jul 21, 2006)

It's not clear what these files contain. I downloaded the 1 KHz version which has six sections. Is the first section one device, then the other device, then the first device again etc? If so, one reason they sound different is because the 2nd, 4th, and 6th sections are more than 1 dB louder than the other sections! If you want to learn how the "modded" version differs, here's what you need to do:

1) Record the output of the devices directly, not after playing through a loudspeaker!

2) Save the files as Wave (or AIFF on a Mac) and upload those for us to retrieve. MP4 type lossy compression is not suitable for analyzing subtle differences between audio files.

3) Describe clearly what is in the file(s) so we don't have to guess.

Then, even if one device is louder, I can account for that when assessing the difference between the devices.

--Ethan


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## jonlanghoff (Nov 25, 2015)

Ethan Winer said:


> It's not clear what these files contain. I downloaded the 1 KHz version which has six sections. Is the first section one device, then the other device, then the first device again etc? If so, one reason they sound different is because the 2nd, 4th, and 6th sections are more than 1 dB louder than the other sections! If you want to learn how the "modded" version differs, here's what you need to do:
> 
> 1) Record the output of the devices directly, not after playing through a loudspeaker!
> 
> ...


Hi Ethan,

Thanks for the reply and sorry, you're of course right - I should've explained what's in the recordings:
The two players are joined within the Sonos controller to play the same file simultaneously. On each of the four recordings above it's then 3 second sound bites alternating between the two players - beginning with the standard device, then the modded, standard, modded, standard and finally the modded.

You're also right with regards to the volume, which is slightly higher on the modded version (as expected). However, I don't think that this accounts fully for the changed characteristics of the sound, especially on the 1 khz sound bite. If it's the sound of jitter, I cannot say, but it's definitely different.

When I'm getting to do the real analysis stuff, I'm of course going to record the outputs directly and in some lossless format. This was just a very crude initial comparison.

These are two other recordings of the same glorious quality: :wink2:
Standard - https://www.dropbox.com/s/px7cnwimnr6hywz/1khz-standard.m4a?dl=0
Modded - https://www.dropbox.com/s/9sfytpd18hajse3/1khz-modded.m4a?dl=0
Please feel free to adjust the volume in order to compare them properly! :smile:

B.R. Jon


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## AudiocRaver (Jun 6, 2012)

Should be pretty easy to take a couple of measurements using pre-recorded waveforms and REW's Real-Time-Analyzer (RTA) function.


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## Ethan Winer (Jul 21, 2006)

jonlanghoff said:


> I don't think that this accounts fully for the changed characteristics of the sound, especially on the 1 khz sound bite. If it's the sound of jitter, I cannot say, but it's definitely different.


Thanks for clarifying. Since you plan to record new files directly rather than acoustically, I'll just wait for those because that's much better for analysis. I assure you that jitter is not an audible problem, so whatever difference exists between normal and modded has nothing to do with jitter. What we notice most is frequency response, followed by distortion and noise depending on their loudness. I've seen more than one "mod" that simply goosed the highs above 5 KHz by a few dB! That alone makes music sound clearer and "more detailed" etc.

--Ethan


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## jonlanghoff (Nov 25, 2015)

Ethan Winer said:


> Thanks for clarifying. Since you plan to record new files directly rather than acoustically, I'll just wait for those because that's much better for analysis. I assure you that jitter is not an audible problem, so whatever difference exists between normal and modded has nothing to do with jitter. *What we notice most is frequency response, followed by distortion and noise depending on their loudness. I've seen more than one "mod" that simply goosed the highs above 5 KHz by a few dB! That alone makes music sound clearer and "more detailed" etc.*
> 
> --Ethan


Yeah, I also expect to see results along those lines and if that's actually the case, then I'll have to sell the modded Connect again, as I of course don't want my media player to color the sound, purposely!

My computer croaked last week, so I'm currently waiting to receive parts for a new one. When it's built I'll do some recordings directly from amp to computer and post them here.

Stay tuned! :wave:


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## AudiocRaver (Jun 6, 2012)

I agree with Ethan. Minimize/eliminate variables, take measurements. It seems pretty unlikely that jitter alone accounts for the difference you have perceived.


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## Ethan Winer (Jul 21, 2006)

^^^ LOL, yes, it's never jitter. _Never._


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## AudiocRaver (Jun 6, 2012)

Ethan Winer said:


> ^^^ LOL, yes, it's never jitter. _Never._


Sorry, Ethan, not arguing, I just have difficulty using the words _Never_ and _Always._ Somewhere, in a parallel universe.........0

We'll just call it a personal problem.


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## Ethan Winer (Jul 21, 2006)

Well, you know what I mean. (Though jitter really is never a problem.)


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## jonlanghoff (Nov 25, 2015)

I've finally made some measurements with the amp connected directly to my computer's soundcard - no mics involved.



It turns out that the difference I can hear when playing the 1khz test tone through my speakers doesn't appear when recording in this way. That "harshness" that I could hear on the non-modded Sonos Connect now also comes from the modded one, and what seems to be the deciding factor is the volume settings. Can't quite figure out why...

This link contains 4 four measurements from the standard Connect and 4 four from the modded Connect - at full volume, 90%, 80% and 70%:
https://www.dropbox.com/sh/twd8hostzbkw288/AAAfQnRiUgOMg9r1WTZ-Ii-ia?dl=0



1) Any thoughts on this phenomenon? - Is the described harshness at 90% and 100% volume a result of some sort of clipping? - Or is it actually meant to sound like that??

2) Also, are there any other differences between the output of the two players, when comparing?



Thanks,
Jon


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## Ethan Winer (Jul 21, 2006)

Yes, the 90 and 100 files in both sets are severely clipped. This is easy to see just looking at the wave forms. I looked at an FFT but didn't add up all the harmonics. I'll estimate about 30 percent distortion.

--Ethan


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## AudiocRaver (Jun 6, 2012)

That would sound a little harsh.


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## jonlanghoff (Nov 25, 2015)

Ethan Winer said:


> Yes, the 90 and 100 files in both sets are severely clipped. This is easy to see just looking at the wave forms. I looked at an FFT but didn't add up all the harmonics. I'll estimate about 30 percent distortion.


Wow, kinda catastrophic that Sonos would sell a product that does that. Or is it just the digital input on my amp that's being a little wimp?
I guess I'll just have to turn down the volume with the Sonos controller - I've always had it on fixed volume (100%) and then adjusted volume on my amp, but I guess that isn't a very good idea then!



AudiocRaver said:


> That would sound a little harsh.


Not to mention potentially devastating for the speakers, right?
Also, as I've written futher back in this thread, I've experienced some harsh S sounds from the vocals when playing loud. I guess this could be the explanation for that..?


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## lovinthehd (Mar 17, 2012)

Saw this with a search https://en.community.sonos.com/components-228996/volume-level-using-sonos-connect-5214661 and https://sonos.custhelp.com/app/answers/detail/a_id/997

Just what is your setup?


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## jonlanghoff (Nov 25, 2015)

lovinthehd said:


> Saw this with a search https://en.community.sonos.com/components-228996/volume-level-using-sonos-connect-5214661 and https://sonos.custhelp.com/app/answers/detail/a_id/997


Yeah, I've searched the issue myself for a while, and other people complain over clipping from the Sonos Connect. I guess maybe it has to do with how sensitive the digital input is on one's DAC.



lovinthehd said:


> Just what is your setup?


My setup is:
Sonos Connect --> digital coax cable --> DAC --> 2x phono --> amplifier --> speakers

BTW, I've tried with two different DACs - FiiO D03k Taishan and the one built into my amp (Primare I22) - which yields the same results with regards to the clipping issue.


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## lovinthehd (Mar 17, 2012)

Might want to review gain structure too http://www.hometheatershack.com/for...ing-most-pro-audio-equipment-your-system.html


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## Ethan Winer (Jul 21, 2006)

lovinthehd said:


> Might want to review gain structure too


Right, clipping is mostly an analog issue. It depends on where the volume control is in the chain, and whether it's digital or analog.

--Ethan


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## jonlanghoff (Nov 25, 2015)

Between the Sonos Connect and the DAC I have a DSP, and it appears that if I use that to define a gain of -10 dB to the signal, then no clipping occur and the 1 kHz tone is nice and pretty - both when listening and when looking (at the waveform in Audacity).
I guess this tells us that the signal leaving the Connect isn't "clipped", as such - otherwise I wouldn't be able to recover the correct signal, am I right? - It must have something to do with the DAC just not being able to interpret the signal correctly per default, for some reason. Notice, that I've tried with two different DAC models, with the same results.


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## jonlanghoff (Nov 25, 2015)

Now that I've "solved" the clipping issue, does anyone have any suggestions/requests as to how to compare the oh-so-jittery standard Sonos Connect and the modded one? - Which testing would, theoretically, exhibit the jitter the most?

I'll gladly do some measurements/recordings if someone is willing to assist in analyzing the results. :boxer:

B.R. Jon


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## Ethan Winer (Jul 21, 2006)

Testing.


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## jonlanghoff (Nov 25, 2015)

Ethan Winer said:


> Testing.


Roger that


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## Ethan Winer (Jul 21, 2006)

Now I don't even remember what I posted, that never showed up. It probably wasn't that important. :surprise:

Are there any outstanding issues still?

--Ethan


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## jonlanghoff (Nov 25, 2015)

If you have any suggestions to how to expose differences between the standard player and the modded one, then I'm all ears. 

I'll do the measurements and then hopefully you or someone else will help me do the analysis afterwards.

B.R.


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## AudiocRaver (Jun 6, 2012)

It will be difficult, if not impossible, to hear. Ethan would say just plain _impossible._ I say _probably impossible,_ a subtle but satisfying difference to my own sense that while many things are highly improbable, nothing is impossible. Sorry, Ethan, just the way I'm wired, I kinda can't help myself.

I usually like to listen first, then measure. Try music that is simpler, not too busy, and contains bells, glockenspiel, xylophone, wind chimes, cymbals, etc. Make sure there is no clipping of any peaks. Create a setup that makes instant A-B switching possible. Listen and switch back and forth. When you THINK you hear a difference, listen again and ask yourself for clarity, "Was there really a difference? If there was, I want to koow. If not, I want to know that, too." Do not try to identify which is which, try to identify the one you prefer, then see if that leads you to the same one all or most of the time. You really need a second party to help make that a blind test for it to be most meaningful.

This also sounds like an interesting situation for recording (digitizing with a Digital Audio Workstation, or DAW) both signals, inverting one, adding together (= subtraction), and seeing what is left over. If nothing is left over, there is zero difference. It's worth a try.


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## jonlanghoff (Nov 25, 2015)

AudiocRaver said:


> It will be difficult, if not impossible, to hear. Ethan would say just plain _impossible._ I say _probably impossible,_ a subtle but satisfying difference to my own sense that while many things are highly improbable, nothing is impossible. Sorry, Ethan, just the way I'm wired, I kinda can't help myself.


I'm much like you in that sense - I suspect little to no difference between the two players, but I wont rule out anything until I feel that I've tested it out properly.



AudiocRaver said:


> I usually like to listen first, then measure. Try music that is simpler, not too busy, and contains bells, glockenspiel, xylophone, wind chimes, cymbals, etc. Make sure there is no clipping of any peaks. Create a setup that makes instant A-B switching possible. Listen and switch back and forth. When you THINK you hear a difference, listen again and ask yourself for clarity, "Was there really a difference? If there was, I want to koow. If not, I want to know that, too." Do not try to identify which is which, try to identify the one you prefer, then see if that leads you to the same one all or most of the time. You really need a second party to help make that a blind test for it to be most meaningful.


I have an ABX testing session in mind with a few people:
* Two semi audio enthusiasts who probably know the term "jitter", but I suspect have no bias on the topic.
* An academic musician (trumpet and composition) with very good pitch - doesn't really care about gear, though.
* The guy from whom I bought the modded Sonos Connect over the Internet - used all of the known audiophile platitudes when we wrote back and forth; strong bias.
And then I'll simply facilitate the session, switching back and forth between the "jittery" and "non-jittery" source.
Great input on the types of music to be used! Thx.



AudiocRaver said:


> This also sounds like an interesting situation for recording (digitizing with a Digital Audio Workstation, or DAW) both signals, inverting one, adding together (= subtraction), and seeing what is left over. If nothing is left over, there is zero difference. It's worth a try.


I don't think that I have a "digital in" on my computer, but I think I'll see if one can be acquired for a reasonable amount of money. Again, suggestions are welcome!


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## Ethan Winer (Jul 21, 2006)

AudiocRaver said:


> It will be difficult, if not impossible, to hear. Ethan would say just plain _impossible._ I say _probably impossible,_ a subtle but satisfying difference to my own sense that while many things are highly improbable, nothing is impossible. Sorry, Ethan, just the way I'm wired, I kinda can't help myself.


LOL, without knowing what these "mods" entail it's anyone's guess if the difference is audible. For all I know they do something that makes the sound worse, but in a "pleasing" way. So we have no disagreement so far. 



> Try music that is simpler, not too busy, and contains bells, glockenspiel, xylophone, wind chimes, cymbals, etc.


Yes! Percussive bells are the most difficult sound for a recording medium to handle, and low frequency IM distortion "grunge" is readily apparent because the music itself is mostly higher frequencies.

--Ethan


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## jonlanghoff (Nov 25, 2015)

Hi guys,


I went and got me a used one of these today - M-Audio Audiophile 2496 - for an amount equivalent to $15.
It has a digi coax input, so now I can connect the Connect directly to my computer.

These are samples of the same audio track for comparisson:
Regular Sonos Connect
Modded Sonos Connect

I've chosen the song for its crash cymbals 30 seconds in.


B.R. Jon


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## Ethan Winer (Jul 21, 2006)

My best suggestion is to set up a blind test that lets you easily switch back and forth, with someone else switching of course. Then you'll know for sure if there's a quality difference. Of course the volume levels have to be matched exactly.

What exactly is claimed for the mods? Do you have a link to the mod company's web page?

--Ethan


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## jonlanghoff (Nov 25, 2015)

Ethan Winer said:


> My best suggestion is to set up a blind test that lets you easily switch back and forth, with someone else switching of course. Then you'll know for sure if there's a quality difference. Of course the volume levels have to be matched exactly.
> 
> What exactly is claimed for the mods? Do you have a link to the mod company's web page?
> 
> --Ethan


I'm definitely going to try that, as desribed earlier in the thread - but I would also like to compare the sources more "quantifiably". Step one being to ensure that the outputs at least arent totally alike..!
At the moment I'm looking into how to confiure Audacity (or some other application) to record "bit perfect" from the two devices. Not sure if the above samples have been made with the sufficient settings to do so.


The modding is done by a guy called Dr. Gert Volk (I, perhaps naïvely, presume that he's in fact a real person - and a doctor, for that matter). He exists/exsisted on some German forums where he made a name for himself, but I don't think there's even a website...

This how the mod is described:

*What I did: The original clock has been removed and a very pricise new clock came in (jitter is about 1ps!). Very important for the performance of the clock ist the power supply, so I did everything what can be done concerning the supply. Now the superclock controls the data acquisition. Anyhow, on the way through the chips the rising edge of data and clock becomes a little bit fuzzy - so reclocking of the s/pdif data stream by the same superclock is done. The reclocker is a FIFO memory (first in first out).

Digital data can be different either because data (high and low) is different, or because the timing of the data is different. Fuzziness of timing (jitter) is the analogue component of digital data. It produces destortion of the analogue signal in the DA converter process. Unfortunately one can not remove the jitter of the source completely in the DAC, there is some jitter remaining, even if you try to remove it by asynchronous sample rate converters and so on - cross-talk is the reason.

So the best you con do is to assure that the data stream coming from the digital source is as accurate as possible.
*


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## jonlanghoff (Nov 25, 2015)

I've done some more comparisons and this time I know that they are reliable. I ensured this by capturing the same sound twice with the same player, inverting the first track and then combining the two - and note that the result was indeed silence.

The actual comparison between the two Connects was then of course done by:
1) Capturing a piece of music played by the standard Sonos Connect and inverting it
2) Capturing the same piece of music played by the Dr. Volk-modded Sonos Connect
3) Mixing the two tracks into a new one, showing the difference

I used Total Recorder for the capturing part and Audacity for the rest.

"Setting Me Up" by Dire Straits was used to do a drums test:
The diff pretty much consists of some clicking sounds when the snare hits. What could this mean?

"Ripe and Ruin" by Alt-J was used to do a vocals test:
The diff is totally silent, but then suddenly (around 23 seconds in) something close to the full sound content appears (but not entirely). Could this be the result of a bit being dropped/lost/skipped by one of the players, perhaps because of the alleged improved clock in the modded one?

"Tubular Bells, pt. 1" by Mike Oldfield was used to do a bells/xylophone test:
Same phenomenon as with the one above.

The test data can be found here, stored as Audacity project files: https://www.dropbox.com/s/s8bn58t6lzmx100/compares.rar?dl=0


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## jonlanghoff (Nov 25, 2015)

Here's another (longer) one with drums:
https://www.dropbox.com/s/jqo5xuk90mv48xb/steely.rar?dl=0

Same thing. Clicks and pops in the diff track.

Thoughts?


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## Ethan Winer (Jul 21, 2006)

jonlanghoff said:


> This how the mod is described:





jonlanghoff said:


> I ensured this by capturing the same sound twice with the same player, inverting the first track and then combining the two - and note that the result was indeed silence.


Well there's your answer. The mod does nothing at all to improve or even change the audio. :sarcastic:

--Ethan


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## jonlanghoff (Nov 25, 2015)

Ethan Winer said:


> Well there's your answer. The mod does nothing at all to improve or even change the audio. :sarcastic:
> 
> --Ethan


No no, read again! 

I was discribing how I ensured that the recording *method *was bit perfect (before doing the comparison between the modded and unmodded player) - by first recording the same file *twice* from the *same* player and then comparing. This resulted in silence.

Afterwards, when finding the "diff" between the modded and unmodded player I got some different results. Most notably with music files containing drums.


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## Ethan Winer (Jul 21, 2006)

Ah, I read too fast!


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## Ethan Winer (Jul 21, 2006)

I don't have Audacity so the only file type I can easily deal with is Waves or AIFF, or (with extra effort) FLAC.


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## jonlanghoff (Nov 25, 2015)

Ah, sure, here you go:

Standard Connect:
https://www.dropbox.com/s/icrl9gnnvunmz4g/unmodded_SteelyDan.wav?dl=0

Modded Connect:
https://www.dropbox.com/s/3ot969g8urwufhi/modded_SteelyDan.wav?dl=0

The diff between the two:
https://www.dropbox.com/s/1vda9daicb5s3y1/diff_SteelyDan.wav?dl=0

If you have any ideas of how to do it, I'd love to have some help analyzing the tracks against each other, besides from just "subtracting" them as done in the third file here... And then of course some thoughts on the results of the analysis afterwards!


B.R. Jon


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## jonlanghoff (Nov 25, 2015)

Anybody had the chance to take a look at my recordings?


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## Ethan Winer (Jul 21, 2006)

The highest peaks are slightly different, with the unmodded version 0.6 dB higher. But obviously the volumes are identical otherwise, because all we get after nulling the files is clicks and pops. I nulled the files and got the same result as your nulled file. The modded version also has the polarity reversed. So it seems to me the modded version is clipped at a level 0.6 dB softer than the unmodded, which cut off a few peaks slightly. This implies the modded device has less headroom. But basically there's no real difference. So if anything the mod is a step backwards because it has less headroom.

--Ethan


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## AudiocRaver (Jun 6, 2012)

Apologies for falling behind.

I looked at the recordings and did the same analysis that has been discussed, inverting one and summing together. I saw the same result and came to the same conclusion that others did, that the modded version of the file clipped in a few spots. Other than that, the two recordings appear - and sound - identical.


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## jonlanghoff (Nov 25, 2015)

Thanks, both of you! 

Can I ask you how you can tell that clipping occur? - There is a setting in Audacity that automatically highlights clippings with a red indicator, but this appearantly isn't the case here though..?


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## Ethan Winer (Jul 21, 2006)

I can't know for sure if the modded file was clipped, but that's a reasonable explanation for no differences other than soft little bursts of sound after nulling the two files. Understand that clipping doesn't happen only in files that butt up against 0 dBFS. One of the demos in my Audio Expert book started with a recording of a gentle acoustic guitar. Then I raised the volume to 2 dB over 0, then I lowered it again to sound the same as the original recording for a fair comparison. In this case the processed file won't be detected as "clipped" because it's no longer close to or at 0. But if you zoom way in on the wave form you'll see some of the peaks have flat tops. There's no way for software to know the flat tops were the result of previous clipping.

--Ethan


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## jonlanghoff (Nov 25, 2015)

Ethan Winer said:


> I can't know for sure if the modded file was clipped, but that's a reasonable explanation for no differences other than soft little bursts of sound after nulling the two files. Understand that clipping doesn't happen only in files that butt up against 0 dBFS. One of the demos in my Audio Expert book started with a recording of a gentle acoustic guitar. Then I raised the volume to 2 dB over 0, then I lowered it again to sound the same as the original recording for a fair comparison. In this case the processed file won't be detected as "clipped" because it's no longer close to or at 0. But if you zoom way in on the wave form you'll see some of the peaks have flat tops. There's no way for software to know the flat tops were the result of previous clipping.
> 
> --Ethan


Excellent explanation. Thanks Ethan.


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## Ethan Winer (Jul 21, 2006)

So I guess this is now wrapped up successfully.  I don't always check in here regularly, or receive email notices of new activity. So if anyone wants my opinion on anything further, you're welcome to email me from my web site: http://ethanwiner.com/


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