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Understanding Jitter in Digital Audio: Measurements and Listening Tests
- Thread starter amirm
- Start date
It is important to understand that the measurements shown are not the actual jitter but the result of it. A jitter is a repeated square pulse (clock) that is shown on a screen (scope or PC) and it's rise time is not steady. It is smeared from early or late rise. Such, may have a max. (peak) jitter value, an average jitter value and so on. As a clock goes on for 44.1k times per Sec. or more (oversampling), A vast number is accumulated during the time.
If that display, shows all rises of that wave (clock) over time, magnified on the time scales, what we see is not a narrow line but a thick one. the width of that line is the actual jitter...
What it does to sound and how it is reflected on it's spectral view is a different thing, even though, they are connected, as one is the direct outcome of the other.
If that display, shows all rises of that wave (clock) over time, magnified on the time scales, what we see is not a narrow line but a thick one. the width of that line is the actual jitter...
What it does to sound and how it is reflected on it's spectral view is a different thing, even though, they are connected, as one is the direct outcome of the other.
Daniel lombardy
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Yet another video, this time on topic of jitter. It is a tough topic to cover and I had to do it over and simplify it from my first "take." Hopefully you can follow it.
Article: understanding digital audio measurements: https://www.audiosciencereview.com/...derstanding-digital-audio-measurements.10523/ SPL
Phonitor X Review (DAC & Headphone Amp): https://www.audiosciencereview.com/...pl-phonitor-x-review-dac-headphone-amp.21114/
Julian Dunn on Jitter:
https://www.aes.org/e-lib/browse.cfm?elib=6111
https://www.aes.org/e-lib/browse.cfm?elib=6772 Jitter Audibility: https://www.aes.org/e-lib/browse.cfm?elib=8354
I just discovered your youtube channel yesterday 3/13/2021 and then found your web site. I really like and appreciative your expert and truthful information and reviews. I really liked the video about speaker cables and RF noise and that Audio Quest interconnect cable video. Some of the best value I have found for interconnect Cable is Bluejeans Cable in Seattle WA. https://www.bluejeanscable.com/store/audio/index.htm .
I have been watching Danny at GR Research for over a year and actually built his X-Statik loudspeakers. They turned out real nice and sound great. I really appreciate your debunking of many of these claims that audio manufactures make about their products. I have been an Audio Enthusiast for 40+ years and have in that amount of time, have wasted much money on products that were basically snake oil but I have also found products that work great for very good value. Thank you for all you do.
Snake oil: Sorry to say that alouding it in our shrin is a shame. Mostly with cables, but not only. I'll try to get the spotlight over some.
Directional wire: Audio is AC, basically a combination of sine waves (Nyquist theory to go digital is based on that). So that means that the current flower 50% of the time one direction and the other 50%, the opposite direction. So if there would be a directional cable (do no exists), in what half would it benefit the sound?
Copper purity: Copper wires that meant for the electrical industry, is higher than 99%. So no matter what purity is promised (doubted if kept) is getting better by up to 1%. Mostly it is 99.8% and the gap to improve is only 0.2%. It will not be audible if two wires compared, one with 99.5% and 99.8%.
Silver: it is on the web: silver conductivity is: 15.87 nΩ·m (at 20 °C) (https://en.wikipedia.org/wiki/Silver) and copper conductivity is 16.78 nΩ·m (at 20 °C) (https://en.wikipedia.org/wiki/Copper). in other words silver conducts by 5.7%. Using a copper wire, with a cross section of 5.7% more than the silver copper would equal the two. For price, silver is more than 100 times more expensive!
Skin effect: Usually, found in way higher Fr. than Audio. However, there is a degradation when it goes high power. But there are some reservations on that subject. A thick wire, may drive hundreds of amp's, but full power bandwidth is low (see AWG table). But the higher currents are at low Fr. At higher Fr. it's low to very low. anything above 10kHz are harmonies. So even that cable has more to deliver at those high Fr. to frie the tweeters.
There are more, but it becomes long...However, if we talk about Speaker Cables, picking a pair, is not a shot in the dark. there is a way to properly calculate it, vs DF and length. The cable do play an important roll and shall be treated accordingly. No cable manufacturer does that. They all keep making the average of #12 to #14 AWG cables, as they fit into the banana plugs and spades on the market. What a shame.
Directional wire: Audio is AC, basically a combination of sine waves (Nyquist theory to go digital is based on that). So that means that the current flower 50% of the time one direction and the other 50%, the opposite direction. So if there would be a directional cable (do no exists), in what half would it benefit the sound?
Copper purity: Copper wires that meant for the electrical industry, is higher than 99%. So no matter what purity is promised (doubted if kept) is getting better by up to 1%. Mostly it is 99.8% and the gap to improve is only 0.2%. It will not be audible if two wires compared, one with 99.5% and 99.8%.
Silver: it is on the web: silver conductivity is: 15.87 nΩ·m (at 20 °C) (https://en.wikipedia.org/wiki/Silver) and copper conductivity is 16.78 nΩ·m (at 20 °C) (https://en.wikipedia.org/wiki/Copper). in other words silver conducts by 5.7%. Using a copper wire, with a cross section of 5.7% more than the silver copper would equal the two. For price, silver is more than 100 times more expensive!
Skin effect: Usually, found in way higher Fr. than Audio. However, there is a degradation when it goes high power. But there are some reservations on that subject. A thick wire, may drive hundreds of amp's, but full power bandwidth is low (see AWG table). But the higher currents are at low Fr. At higher Fr. it's low to very low. anything above 10kHz are harmonies. So even that cable has more to deliver at those high Fr. to frie the tweeters.
There are more, but it becomes long...However, if we talk about Speaker Cables, picking a pair, is not a shot in the dark. there is a way to properly calculate it, vs DF and length. The cable do play an important roll and shall be treated accordingly. No cable manufacturer does that. They all keep making the average of #12 to #14 AWG cables, as they fit into the banana plugs and spades on the market. What a shame.
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Directional cables has nothing to do with the flow of electrons. they are shielded rca cables that are not coaxial, so the shield is only connected to ground at one end, Tipically by convention at the sending end, the shield should be connected to the ground, but not be part of the signal, that would be an impedance differential, so it’s one way to do it, but coaxial transmission line type rca cables avoid that.
I'm talking about directional speaker cables!
For your explanation on interconnects, What would be the ref of such signal without ground? not to say that by Kirhof low, if you do not close the loop, there is no current! It may apply if so, if the chassis grounds are connected, of the two components, and a double grounding has a ground loop noise. Disconnecting one would be the solution. Never seen a directional interconnect comes with that explanation. It just came in general that a directional cable is better, as the other cable, does not have that feature...
For your explanation on interconnects, What would be the ref of such signal without ground? not to say that by Kirhof low, if you do not close the loop, there is no current! It may apply if so, if the chassis grounds are connected, of the two components, and a double grounding has a ground loop noise. Disconnecting one would be the solution. Never seen a directional interconnect comes with that explanation. It just came in general that a directional cable is better, as the other cable, does not have that feature...
I’m not sure what you mean by “without ground” a rca connector has two point of connection, signal and ground. you can use a twisted pair and leave it unshielded, or you can use a third wire like for turntable and screw it to the chassis, or you can use a coax transmission line, but you can’tconnect the shield to ground at both end, the shield becomes part of the return path. basically, the shielded cable I’m talking about has 3 conductor, the rca has 2, of course the current loop is closed, it’s about what to do if you want it shielded, for unbalanced connection
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There are two kinds of "directional" cables on the market:
- Cables with asymmetric construction, such as a semi-floating shield. The direction these are connected can obviously make a difference.
- Cables for which the manufacturer makes outlandish claims, for example how they listen to each reel of bulk wire in each direction in order to determine which is better, then mark the finished cable accordingly. This is snake oil.
Silver has better corrosion resistance than copper and to me seems easier to get a solid solder joint than copper. I use silver-plated signal wires and I don't have any illusions. On a Sea Hawk helicopter, all the wiring is silver plated because of the benefits stated. In a domestic environment it might take 50, 100, or 1000 years to make a difference, so we are well into diminishing returns before we add any silver, but there are advantages. Obviously it doesn't sound different than copper that isn't broken.
XLR cable assemblies are directional because they have male connectors on one end and female on the other.
XLR cable assemblies are directional because they have male connectors on one end and female on the other.
XLR: The fact that cables have a Mail connector on one end and a Female on the other, is not for directionality. It's to protect a long cable from connect Out to Out. It's for fool proof from miss connecting. No XLR naker claims for directionality. XLR is for pro audio, They seems to understand better.
What is a directionality in AC? nothing but a BS invention for the ignorants.
What is a directionality in AC? nothing but a BS invention for the ignorants.
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Silver: 1. The word better is marginal. 5.7%. A wire resistance = to the metal Q x L (in meters) / S (cross sections, in mm2). To compensate on the material conductivity, all you need to keep the formula equal, is to add 5.7% to the copper wire cross section. Doing that would result by two cable (Silver and 5.7% thicker copper) with equal conductivity or resistance. Cost wise, the silver is more than x100 times more expensive.
For corrosion resistance, it's more that the silver oxide conducts better than copper oxide. But a well made cable is not exposed to such problems. A thin coating would save the metal from oxidation. It is also NOT out there for elements, as the seahawk helicopter. Oh, the broken and 1000 years are good. lets delay the debate by 1000 years to see if you were right
For corrosion resistance, it's more that the silver oxide conducts better than copper oxide. But a well made cable is not exposed to such problems. A thin coating would save the metal from oxidation. It is also NOT out there for elements, as the seahawk helicopter. Oh, the broken and 1000 years are good. lets delay the debate by 1000 years to see if you were right
I don't disagree with any of this. We are just using 'directional' differently. Male-to-female or female-to-male are what I would call directions. I wasn't talking about the AC electricity. It doesn't care. that's why I explicitly stated I was talking about the gender of the connectors only.
I don't disagree with any of this either.Silver: 1. The word better is marginal. 5.7%. A wire resistance = to the metal Q x L (in meters) / S (cross sections, in mm2). To compensate on the material conductivity, all you need to keep the formula equal, is to add 5.7% to the copper wire cross section. Doing that would result by two cable (Silver and 5.7% thicker copper) with equal conductivity or resistance. Cost wise, the silver is more than x100 times more expensive.
For corrosion resistance, it's more that the silver oxide conducts better than copper oxide. But a well made cable is not exposed to such problems. A thin coating would save the metal from oxidation. It is also NOT out there for elements, as the seahawk helicopter. Oh, the broken and 1000 years are good. lets delay the debate by 1000 years to see if you were right
That's why I qualified what I said, with pretty much the exact same points you are making. I spent countless days in Sea Hawks getting blasted with water from all directions. I understand as well as anyone that they are different from a house.
We have no argument here.
carsknivesbeer
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Thanks, Amir. Really enjoying the digital audio processing primers. For anyone interested in learning about this stuff in a structured yet accessible way can I suggest a visit to Akash Murthy's YouTube channel starting with:
Signal Paths - Digital Audio Fundamentals
The 2nd video in the series, Sampling Theorem - Digital Audio Fundamentals, totally nails the reason that 44.1kHz was chosen as the sampling frequency for Red Book audio (CDs) and presents Nyquist Theorem in a manner that even the most die hard subjectivist will derive some appreciation from.
The videos are beautifully animated and presented in a clear and non-patronising manner and serve to give a solid foundation to the concepts that Amir has been discussing. Absolutely Ace
Akash also links to some short presentations on Psychoacoustics by Professor Susan Rogers at Berklee which explain how our ears interpret consonance and dissonance which Amir has touched on in previous videos, also very enlightening.
Thank you so much for posting these videos. They are concise, very well done, and have filled in some gaps/confusions I had.
Astoneroad
Major Contributor
I recently went into my dealer to audition speakers. I thought that I'd be able to listen to music streamed from Tidal connect from my phone (Samsung S8 plus) to their system, since I know my playlists. The owner said no, that would introduce "Jitter", so he plugged his phone into the usb connection of each system that we listened to and played my requests. He was very adamant on this point and was a little condescending when I expressed doubt. Is he correct?Yet another video, this time on topic of jitter. It is a tough topic to cover and I had to do it over and simplify it from my first "take." Hopefully you can follow it.
Article: understanding digital audio measurements: https://www.audiosciencereview.com/...derstanding-digital-audio-measurements.10523/ SPL
Phonitor X Review (DAC & Headphone Amp): https://www.audiosciencereview.com/...pl-phonitor-x-review-dac-headphone-amp.21114/
Julian Dunn on Jitter:
https://www.aes.org/e-lib/browse.cfm?elib=6111
https://www.aes.org/e-lib/browse.cfm?elib=6772 Jitter Audibility: https://www.aes.org/e-lib/browse.cfm?elib=8354
Run away. Now.
Astoneroad
Major Contributor
I did, actually. So, I'm guessing that he was not correct? I only listen to streaming "Hi res" music, and left there thinking that everything that I listened to, using my phone via WiFi to my system, wasn't what I thought, but full of "Jitter". It was disheartening until I thought... "I'm too old (65) to hear it anyways..."... lol.
“Jitter” is one of those magic terms used to scare audiophiles for fun and profit. The ONLY jitter that matters is the clock at the DAC chip. And that’s not affected at all by what you wanted to do. Either the dealer is totally ignorant about how digital audio works, or he isn’t but is happy to lie. Either way, not someone you want to trust.
Also, even for clock jitter, human sensitivity is not even close to real world values. By like a factor of a thousand.
Astoneroad
Major Contributor
Thanks, that's what I took away from Amir's vid on the topic, but wasn't sure how it related to my experience with components and facts. Well... good thing we've got Amir to prove or disprove all these "Spooky actions at a distance". Is there any truth to the rumor (that I just made up) that Amir is on the short list for a Nobel Prize?... well my short list at least.
Thanks Amir
Following your video I finally understood why we
had a skirt at the bottom of the FFT analysis of the
fundamental frequency.
So I used the paper by "Julian Dunn" that
can be found on the Net.
So I simulated a jitter on a frequency of 1 kHz,
to which I added a noise in the equation that I
limited in frequency to 30Hz low-pass filtering
1st order in audacity.
Here is the simulation, and it is very close in form to a signal
output from a DAC, here the Topping D10S.
This allows me to have a better visibility of the measurements.
So thank you thank you thank you.
Following your video I finally understood why we
had a skirt at the bottom of the FFT analysis of the
fundamental frequency.
So I used the paper by "Julian Dunn" that
can be found on the Net.
So I simulated a jitter on a frequency of 1 kHz,
to which I added a noise in the equation that I
limited in frequency to 30Hz low-pass filtering
1st order in audacity.
Here is the simulation, and it is very close in form to a signal
output from a DAC, here the Topping D10S.
This allows me to have a better visibility of the measurements.
So thank you thank you thank you.
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