What does jitter sound like?

Like the sound of one hand clapping.

Jitter is present on all digital transmission systems, in a digital audio system it is only of importance in 2 places, the sample clock on an ADC or a DAC. However digital audio data is transmitted it doesn't matter how much jitter is present on the data stream provided it doesn't cause a data error.

The downstream device would be expected to generate a sample clock of adequate stability whatever the incoming data jitter.

Jitter on the DAC sample clock is measurable by measuring noise sidebands on the audio output.

Interestingly, purveyors of so called jitter busters never seem to publish such measurements, you can draw your own conclusions from that!!!

Dr. Digital,

Would you expect higher jitter to affect the emotion, musicality, and overall foot-tapping nature of the music?

Is it the difference between looking through a net curtain, and opening the window?

Will it make my blacks blacker, and sound-stage more three dimensional?

Would jitter be more audible in the evenings when the electricity is cleaner and the musicality is at its peak, or would the clean electricity actually reduce the jitter than offset this additional insight?

Regards,

follow this one...

I think modern day jitter artifacts sounds like glasses on versus glasses off. If you hear a difference, then jitter will be just as audible. But if you're listening for differences between having your glasses on or not you're probably not listening to the music anyway so it's sorta pointless.

"Oh, Ive gotta follow this one..."

lol :)

I hear jitter, people....

Tim

I've lost the will to live!!!

Ash

You might try this one: http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=26508
I think the post by John Swenson sums it up nicely

One problem with any discussion of digital audio is that the technical description of error requires metaphors that differ from those that describe, however imperfectly, the properties of an analog system. In digital audio there are at least two major variables. One is bandwidth (16 bit/44 kHz, 24 bit/192 kHz, etc). Increasing the information density increases the fidelity of a recording to the original sound. There is an easily perceived video analogy: a bluray dvd delivers a better picture than a standard dvd for the same reason. Second, the quality of a digital audio system also crucially depends upon the fidelity with which the information is retrieved from the source, a CD or a hard drive. This is where jitter comes into play; basically, it is timing error. How does one hear that? We do not hear "jiiter," per se, but if a series of measurements shows that our perception of the sound of a digital audio system varies in a way that is consistent with the amount of this measured property, we are entitled to say, other things equal, that jitter affects sound quality. Here again a video analogy comes to the rescue. Anyone who has watched an old 8 mm home movie made with a cheap camera has probably noticed that the picture flickers. That "flicker" is the film analogy to jitter. An image that flickers causes video fatigue just as listening to a jittery CD player causes audio fatigue, and perhaps one could say that this fatigue is itself evidence for the audibility of jitter. The fact that we are limited to technical descriptions of a phenomenon does not mean that the phenomenon is not real, only that we need a different vocabulary to describe it.

Jitter on a DAC sample clock produces noise sidebands either side of the wanted signal, the level of these sidebands can be calculated and unless the DAC system is really bad the noise sidebands are well down at or below the noise floor.

Hifi gurus often spout theories and scientific fact without any quantitative data to demonstrate the magnitude of the effect especially if they have a magic product to sell.

There are thousands of words by such people on this forum but without solid supporting data they are just words circling a drain!

Ignore them and get on with enjoying your music, leave them to their obsessions about Jitter, the quality of the 0s and 1s, the crystal structure of their cables and any other 'problem' they can invent a magic cure for!

Tim!

For some people, jitter is a voodoo science of digital audio. Bits are bits right? Perfect sound forever, remember…? It turns out it’s not that simple.

How would you pronounce “cho pho use?" Think about it for a while. Sound it out.

What if I wrote it as “chop house?” :)

All I’ve done is change the timing in which the data has come to us. When it comes to audio, a DAC expects data to come let's say, every 1/44100 seconds. If the data comes in a fraction of a second too early, the sound card buffer can overfill. If the data comes in a fraction of a second too late, the DAC has to “guess” at what kind of data it needs to send out. This corrupts the audio resulting in worse fidelity.

If the data comes in a fraction of a second too early, the sound card buffer can overfill. If the data comes in a fraction of a second too late, the DAC has to “guess” at what kind of data it needs to send out.

I wonder if this is correct.
A traditional DAC slaves its clock speed to the incoming data stream.
Therefore there will be no over- or underrun.
If it happens the DAC is not able to correct, it simply loses its lock.

If both source and DAC have word clock, you can slave the source to the DAC.
In recording studios they might use a master clock slaving all devices.

Today’s sound card do buffer the input.
Overrun is a bit unlikely or a matter of a bad driver (most communication inside a computer is bi-directional).
Underrun clould happen but I don’t think a sound card will conjecture up a value (it is not CD error correction) but simply play a loud pop/crackle or any thing else clearly audible.

Streaming audio players are a different kind, they are build with interrupts (internet technology) in mind. They have a large buffer and read this with their own clock. An excellent method to free the DAC from input jitter.

For the ones who do not use asio drivers on windows domain, here's a DPC latency checker that analyses the capabilities of a computer system to handle real-time data streams properly:

http://www.thesycon.de/eng/latency_check.shtml

It may help to find the cause for interruptions in real-time audio streams, also known as drop-outs. ;)

Jitter can sound different depending on the clock that sources the stream to the D/A, but in general in my system it sounds like a "veiling" or for a visual analogy, a film on the window that I'm trying to look out. The glasses on, glasses off analog is a very good one too.

Jitter is modulation of the D/A conversion, so it is a complicated artifact that should be characterized not only in the time, but frequency domain. There are literally no manufacturers that publish the frequency domain data. I believe this jitter is also affected by the digital filtering inside many D/A chips, so what happens is the jitter is actually more damaging using one D/A chip than another.

To give you some examples:

AES papers that I have read (with dubious synthesized jitter stimulus I might add) conclude that jitter below about 20nsec is not audible to humans. Well, the specs on my standard oscillator is 2psec of RMS jitter and the Superclock4 is also 2psec of RMS jitter. The difference in sound between these two however is immediatly apparent in most systems. The Superclock4 is more musical (vivid) and the standard clock is very detailed, but a bit dry sounding. The difference in jitter amplitude between what the AES says I should hear and these oscillators, which I can plainly hear is a factor of 10,000. I think there is some kind of disconnect here.

I believe it is the spectra or frequency content differences that make one more musical than the other. I dont have $50K to spend on test equipment to attempt to quantify and correlate this. I only know what sounds good. Based on the differences between these two clocks and what the AES believes to be audible, I think measurements are black hole anyway.

It's like amplifier measurements. Lots of amps out there that measure perfectly, but sound lousy. Lots of amps that have high distortion and other poor measurements, but sound like real music.

The problem of inadequate measurement techniques is pervasive in audio equipment IMO. Dont even mention cables.....

Steve N.
Empirical Audio

.....ang judging by these replies, the answer is, it doesnt really exist as an audible quantity.

I would say there are other more apparent audio problems that cause audio listening fatigue than little old jitter.

Loud mixes are one..........

As someone else states on this forum, if it sounds good it is good! If it doesnt then jitter would be well down my list of culprits in computer based audio.

"Jitter can sound different depending on the clock that sources the stream to the D/A, but in general in my system it sounds like a "veiling" or for a visual analogy, a film on the window that I'm trying to look out. The glasses on, glasses off analog is a very good one too."

An excellent pair of time-tested analogies. But if they're valid here, surely these effects would be easily measurable as an attenuation of frequencies by a clearly audible amount?

Tim

"But if they're valid here, surely these effects would be easily measurable as an attenuation of frequencies by a clearly audible amount? "

You would think so, but every time I go to measure these differences, there is no difference. Particularly with a steady-state signal, such as a sine or square-wave. With music data, what do you measure???

I ran into this same enigma when measuring cables that I designed. Two cable sounded radically different, and yet all of the classical measurements showed they were identical. to test this, I suggest that someone reading this builds a cable or takes two identical interconnect cables (digital or analog) and performs the following experiment:

Immerse one of the cables or cable pairs in liquid nitrogen. This shocks all of the materials in it.

Then listen to both cables and hear the difference.

Then go to the bench and measure L, R, and C and do some frequency sweeps to compare them. Use a spectrum analyzer if you have one.

The result will be that they are identical and yet they sound different. I've done this experiment.

Then, find a Time-domain-Reflectometer and do a TDT (Time-domain-Transmission) measurement on the cable with a high-speed step. You will find only tiny reflections at ultra-high frequency as a result of the broken crystal lattice of the conductor metal.

So, how does this affect an audio frequency analog cable? how can you possibly hear this?

Only God knows the answer right now.

Steve N.
Empirical Audio

Perhaps it's more a matter of use of language than one of divine measurement. When I think of "veiled," or "glasses on, glasses off," I think of great chunks of frequency response missing. You must be speaking of something much subtler than I have in mind.

Tim

It's not frequency response.

The problem with 99% of consumer (and most pro gear), is transient response, not frequency response. This is the response to an impulse function.

Most gear compresses the impulse function. This is never in the measurements.

Transient response is anything but subtle. Its how the kettle drums sound when they are beaten with gusto on the start of Also Sprach Zarathustra. What happens with jitter is the transient response is "smeared" and defocused. It's mostly high frequencies affected.

Steve N.
Empirical Audio

Steve,

Quote:
The problem with 99% of consumer (and most pro gear), is transient response, not frequency response. This is the response to an impulse function.

Most gear compresses the impulse function. This is never in the measurements.End Quote.

I presume you have measured this and therefore have the figures to back this up? If so could we see them for ourselves please.

Also a transient response of your USB DAC with valve in it would be intertesting, come to think of it distortion figures would be useful as well.

I hope you can oblige

He said and I quote: "A man who knows how much he knows, knows how little he knows"

The problem with this and all audio discussions and also the reason why scientists and engineers are so intolerant of Audio is that knowledge is limited and misinformation rife. If you consider the USB specification which was developed by Compaq, HP, Lucent, Intel, Microsoft, NEC and Philips, plus plus a few more A4 sheets full, that comprise a Who's Who of the Industry, all who are technical leaders in their particular fields and likely to have done a proper job, you may question why anyone of lesser provenance might believe he knows better.

The best people to judge the merit of these discussions are those with the greatest knowledge and experience. No one with anything less is able see the disagreements as more than probably irreconcilable differences of opinion. Hence the suggestion that we be more laid back about it. The reality is that the ones who could provide clarification wouldn't be or haven't been recognised and as a result they left audio frustrated. It's been happening for many years and must be a significant factor in the decline of the Industry. The best engineers design the best products.

The fact is that contributors to this particular thread have ascending levels of knowledge, don't recognise those with more and so plough on delving deeper and deeper into minutae that means nothing poor old audiophiles who just want their computers to be the main source of their Media and a good sound. Worse than that, it may persuade some of them to buy something expensive for one part of a system that has more serious problems elsewhere.

It's not a good situation and it's not helpful, but worse still it is likely discourage the wider and considerably larger audience that is currently switching to home media computers and limit the scope of this Forum to the tiny and marginalised minority of audiophiles. Shenzi had some ideas that could help, but I do think we need to consider these issues more carefully and not try to dismiss them as differences of opinion, because many are actually contradictions of provable fact.

Ash

Supernatural effects makes a change from quantum effects, I suppose.

The trouble with a lot of listening tests is that it is differences which are claimed and without references to the original recording, how do you tell which is the improvement? A device may sound hard and can be modified to sound warmer, more dimensional, etc but what if none of those things were on the original.

Back to the jitter bugging.

Supernatural effects makes a change from quantum effects, I suppose.

The trouble with a lot of listening tests is that it is differences which are claimed and without references to the original recording, how do you tell which is the improvement? A device may make a piece of music sound hard and clinical and can be modified to sound warmer, more dimensional, etc but what if none of those things were on the original recording? Maybe the producer aimed for hard and clinical.

Back to the jitter bugging.

"minutae that means nothing poor old audiophiles who just want their computers to be the main source of their Media and a good sound."

Have we met? You seem to know me so well.

Actually, I'm thankful for Steve's last response. If jitter mostly effects transient response (which I did not understand is unmeasurable) then I can relax, certain that I need to concentrate on listening. The speed and precision of my system, it's ability to reproduce the impact of the attack of cymbals, bells, drums, etc, is so much better than it was in the old days. Really, I know where to put my money, should I ever come across any - speakers. And then wait patiently for the industry to get over "loudness."

Tim

"Worse than that, it may persuade some of them to buy something expensive for one part of a system that has more serious problems elsewhere.

It's not a good situation and it's not helpful, but worse still it is likely discourage the wider and considerably larger audience that is currently switching to home media computers and limit the scope of this Forum to the tiny and marginalised minority of audiophiles."

Tell it, brother Ashley. Can I get an amen?

To all new to computer audio: It is simple and cheap. Take the shortest path, hook it up to your system and listen. Really. The most complicated thing you might need to do is put an inexpensive DAC, outside of your computer, in line on the way to your system.

If you really love complications or believe you can tweak it to perfection, there will be plenty of time for that later.

Tim

No ..you have definately lost me...
When I first started looking at computer audio I was captivated by the new words that sprang up on many of the sites. Those same sites that were brim full of esoteric amps, dacs and tubes that could be rolled if you were really cool. then there was jitter, complete with dire warnings about its pervasive nature and how any fool would know that it must be destroyed at all costs. To do this may involve handing over a sizable wedge of cash to a very nice man with a jitter demodulator (Bel Canto may have one) or a side pod gizmo usb to spdif jitter deregularizor from Empirical.

I'm sure jitter is real and may well be evil but if you can hear it you will either be totally mad or have a perfect recording.

Me? I'm more concerned about recording quality but I may be tempted by those solid kryptonite isolation platforms from papua New Guinea.

Yours with a mild fever

Tog

Tim, Amen and Hallelujah!!!!!!!

Were we separated at birth?

On behalf of our host and the rest of the loonies in the bin, welcome to CA. I love this place as there seems to be room for tweakers and pragmatists alike, with a fair amount of humor preservation in the mix.

Tim

If you consider the USB specification which was developed by Compaq, HP, Lucent, Intel, Microsoft, NEC and Philips, plus plus a few more A4 sheets full, that comprise a Who's Who of the Industry, all who are technical leaders in their particular fields and likely to have done a proper job, you may question why anyone of lesser provenance might believe he knows better.

Well spoken, I think everybody knows that if any of these companies embark on something like e.g. USB it is always with top quality audio as one of their highest priorities.
The quality of their engineering is unequalled indeed, that's why Microsoft Windows never crashes.
B.t.w. The Who's Who lost a couple of their members years ago (Compaq and Lucent don't exist anymore as independent companies. Hired the wrong engineers?)

Might it be that a site called Computer Audiophile is the right a place to discuss Audiophile topics?

"I presume you have measured this and therefore have the figures to back this up? If so could we see them for ourselves please."

Sure, I make measurements, but there is no standard for transient response measurements, so how can one compare apples-to-apples anyway?

The only thing that is done routinely is a square-wave, which is insufficient. As for slew-rate, my new DAC does .24V/usec with a 1kHz square-wave at -12dB. This tells you nothing about how it will sound.

Transient response should be measured over a wide variety of stimulus, including:

1) different amplitudes
2) different frequencies
3) different loads

I believe that when it's consistent for all of these then it starts to sound like real music. If the industry were to adopt standard stimulus and the above three measurements, then we could start making some valid comparsons among equipment.

Steve N.

If there is no standard way to measure something there are no valid comparisons that can be made but a great deal of tail chasing and head scratching will inevitablly result in someone trying to sell us a device to deal with it - whatever it may or may not be....my head hurts.

Yours in a spin, tog

Given that the adverse effects of jitter are not measurable, may not be audible, are at least arguable and, if real, likely to only be revealed by the most revealing systems, I'd venture that the practical path would be the one Ashley suggested: Start with an inexpensive DAC and see how it sounds. If it doesn't sound as good or better than your cdp did, use it as a reference when auditioning other DACs, clocks, black boxes, etc, and don't buy any that won't take a return with no questions asked. If it does sound as good or better than you cdp, get off the internet and listen to music.

Been there, done that, with the simple 16/44.1 Burr-Brown built into my digital transport.

Tim

...currently doing that with a toslink in to the dac in my receiver. A week into the world of computer audio and it sounds fine. Anything more complex will have to work for a living (an A-D as well as a D-A, for example).

"Given that the adverse effects of jitter are not measurable, may not be audible, are at least arguable and, if real, likely to only be revealed by the most revealing systems, I'd venture that the practical path would be the one Ashley suggested: Start with an inexpensive DAC and see how it sounds. If it doesn't sound as good or better than your cdp did, use it as a reference when auditioning other DACs, clocks, black boxes, etc, and don't buy any that won't take a return with no questions asked. If it does sound as good or better than you cdp, get off the internet and listen to music.

I'd suggest this is a definitive answer. Way to go Tim (and Ashley :)). I specifically champion the "return with no questions asked" part.

--
djp

Tim is exactly right but it occurs to me that the sound of your system can be quite be quite fickle anyway. last night whilst listening to a high bitrate VBR MP3 - no alcohol - no cahnges to the system and the sound was perceptably better than the previous night. Now the loons over at extremeaudiophilespending.com would no doubt say that the mains supply may have been cleaner or that my amps had run themselves in and recommend that I rub linseed oil on my toslink ends....but whatever the reasons the sound was much better. Perhaps I imagined the improvement or there was less wax in my ears but I would swear that the sound was much better than the previous night.

Does this mean that for all our concerns over jitter there are some very real ambient or psychological factors at work?

Indeed does it work both ways ...did I imagine there was a problem with the sound the previous evening?

Yours sober, tog

My hearing is a constant (except that is slowly degrades over the years).
My perception of what I hear is not a constant, it changes in the long run (taste) and it changes in the short run (mood).
Everything 'fickle' in the sound, I attribute to perception
Everything in the sound which is a constant over time I think is real.
If it sounds great today and dull tomorrow it is me.
If it sounds dull today and tomorrow and does so for 3 month in a row, I have bought the wrong stuff.

Mood, energy level, distraction...a million things can change the way you hear the same system from one night to the next. But let's not forget the most important one -- were you listening to the same recordings?

Oh, and Shenzi, I have the opportunity to listen to lots of AV receivers daily, most in that zone between the high reaches of mid-fi (a term I really don't accept as valid) and the entry level of hifi (a term which has more to do with price than performance). Most of them sound very good, even through pretty highly-resolving speakers. I don't know what your AV receiver is or what DAC it contains, but I suspect I would make any potential replacements work hard for their money as well.

Tim

Some interesting reading here,
http://forums.slimdevices.com/showthread.php?t=56425&page=1

As for computer audio, well most of it is pure rubbish, people repeating what someone else speculated without any evidence.

My computer experiences still leave me preferring my CD systems, my music is currently playing through a computer, spdif direct from mobo, high jitter, high clock error, etc etc.

Thankfully, re-clocking and removing the bloody jitter gives audible results. For the guys who do not hear jitter, and that have superior Macs and AVI kit, instead of stating rubbish such as its all unsubstantiated foo, why not leave teh thread alone. Many companies still address such issues you state as imaginary, why not give em a bell and offer them a sugar pill, LOL.

My receiver is a fairly most Teac Legacy 700. I've no idea of the type of DAC inside other than it is 24bit, 96kHz. But as I've said, it sounds fine. Actually the whole receiver sounds fine and I'll be interested to see how the conventional rig compares when it emerges from enforced hibernation.

But thanks for the info on what you've heard. I read a while back that Earl Geddes uses a receiver to dem his comparatively high-end speakers, whiich upsets the golden ear brigade no end.

I may go into business manufacturing heavy-guage, high-end metal enclosures to retro-fit over the top of a modest stereo to pretend it's something more boutique ...

From the earliest days of cd, right through to the present, the overall sound quality of digital is largely dictated by the absence or presence of jitter. Jitter basically destroys the precision of transient signals, resulting in sound that may be described as harsh, cold, smeared, or any of the manifold adjectives that have been used to describe"digititis".Any digital -to- digital transfer is inherently jitter-prone unless re-clocking or other preventative measures are taken. The removal of jitter brings digital audio into another realm, where musical enjoyment is not only possible but predictable. The maturation of digital can be directly traced to jitter reduction throughout the recording &playback chain today. While there are other factors, if significant amounts of (the bad kind) of jitter are present, quality of analogue circuitry, power supply , etc,. will not matter. Only if jitter is residualised will other design aspects surface as important. Jitter elimination remains the key goal in digital audio. Thank You-CA

Hi sastusbulbas - I'm a little slow today as I don't really get what your mean by your statement:

"...As for computer audio, well most of it is pure rubbish, people repeating what someone else speculated without any evidence..."

I get what you're saying in the rest of your post but I'm really interested in reading an elaboration on the above comments.

Thanks sastusbulbas!

Being somewhat familiar with digital data and controls I have always wondered why there was so much press given to the jitter specs of digital transmission devices and protocols. It seems to me that a small bank of dual-ported RAM designed as a FIFO buffer could be used to write the incoming digital data stream, using the transmitting clock for synchronization. Then the data could be read from the FIFO and clocked into the DAC using a very accurate local clock. I believe this would completely eliminate jitter introduced by the digital transmission, leaving only the jitter associated with the local clock, which should not be difficult to minimize below a measurable threshold considered to be acceptable. (Of course any jitter introduced during the sampling of the original audio signal would always be present, but no DAC can overcome that.) Given the cost of medium to high end DACs, I can't imagine that the cost of such a RAM FIFO and local clock would add that much. Perhaps I have oversimplified and overlooked a significant technical issue, can anyone here explain why this approach wouldn't work, or isn't widely used?

Hi John - Welcome to Computer Audiophile. Thanks a lot for the nice post. It clearly sounds like you know what your talking about, but I really like the fact you haven't ruled out every other possibility. Those who know more realize there are many things they don't know. Said another way, those who claim to know it all know nothing. I don't have the answer to your question unfortunately. I just want to thank you for the informed post that does leave the door open for other readers to offer a compelling opinion that hasn't already been shattered by sophomoric internet banter.

Thanks John!

can anyone here explain why this approach wouldn't work, or isn't widely used?
This is exactly how streaming audio works.
- galvanic isolation (network card or wifi)
- big buffer (to avoid drop outs)
- DAC reading the buffer at its own clock speed (no need to lock on a source)
- strict (TCP/IP) or a less strict protocol (UDP)

Yes, it is widely used, any Squeezebox proves this point
No, not in the audiophile world, there stoneage protocols like SPDIF rules.
Same could be observed in case of USB DACs. The first where not from any big name in audio. Now the traditional audio brands are slowly catching up.

Chris asked regarding,

"...As for computer audio, well most of it is pure rubbish, people repeating what someone else speculated without any evidence..."

I get what you're saying in the rest of your post but I'm really interested in reading an elaboration on the above comments.

Thanks.

Hi Chris, a little elaboration, I guess what I am getting at is some of the sweeping statements and sliding remarks made against various areas of performance. Looking through various threads shows a bit of speculation not to mention what seems like the dismissal of jitter (amongst other things) as having any relevance and of anyone who thinks it relevant seeming to be "wrong" regardless. Of course this also includes me, I also repeat others writings, as most only post what they have re-read elsewhere, which is why many question dismissive comment, hence my comment. Stuff such as below,

"Interestingly, purveyors of so called jitter busters never seem to publish such measurements."

"Hifi gurus often spout theories and scientific fact without any quantitative data to demonstrate the magnitude of the effect especially if they have a magic product to sell."

"Given that the adverse effects of jitter are not measurable."

If my memory serves me correctly, many "jitter buster" producers DID provide measurable data backed up with audible benefits, I also think that considering this development really took off during the 90's when manufacturers were starting to get to grips with digital audio, it seems a little naive to dismiss jitter when may companies still seem to be attempting to address it during product design, and many magazines seem to be quite capable of producing measured results. In fact in the late 90's many "jitter busters" were found to only address narrow band jitter at certain frequencies, companies such as Meridian, Genesis and such clearly showed there could be improvements and I think much of this early work helped pioneer development, as many of today's equipment is reported to deal well with jitter.
As companies are prepared to still work on this area, AV equipment for example having extremely high jitter levels via spdif and HDMI, with some speculation as to detrimental performance, 50psec versus 7660psec via HDMI in one recent article stated as debilitating then clearly some still put some importance into what people here are dismissing due to some other guys opinion.
I consider some reason must exist for CD manufacturers to address so many issues of playback performance, clock accuracy, jitter levels, build quality, chip choices, careful circuit layout, power supplies etc, all chosen in many cases for beneficial reasons, and at times cost implementation. Yet so many seem to give variables in measured and audible performance.

Computers have only recently gained in popularity as audio devices, many attempted as early as the mid 90's with audio and computers at home, I still remember hospitality boards on the first PowerMacs allowing connection to a HiFi, with costly CD drive hardware and software such as Toast, and the staggering cost of HD storage, and the subsequent loss of interest during late years due to various detrimental issues regarding SMPs, RFI, and other such things. These days things have moved on, but I think little has been done with computer hardware with regard to audio performance. Hence why I think Macs are popular, there are less variables with performance in comparison to PC, though it is only in recent years Macs have caught up to PC with regards to OS and storage and such. I still remember limited hardware for Macs, and they are still limited in comparison cost to PC spec.
Though no one will specify jitter or clock accuracy, the effect of a SMPS or a GPU interface, which now seem to be dismissed as having no bearing on performance, we seem to have as many opinions as facts with no absolutes or factual evidence.

Don't get me wrong, computer audio is going somewhere, what else is giving such a head start in HD audio and high res music for such costs! and sites such as this help considerably, but I think there is still a lack of knowledge and little naivety in place. The more we see them used for audio at home, the more product may be developed with Audio performance in mind, and teh more people will investigate component performance, for now though just about every Mac and PC is a compromise with the product developed with many other areas in mind.

I myself play with older equipment, we do not all use the same equipment and such, I mainly use 16/44.4 and I prefer an old NOS DAC in my system. I have used Mac and PC through the years, but always preferred my CD transports. I am currently interested in turning an old PC into a music box for upstairs (for 16/44.4) as both my (Old) Macs have failed in succession (HD failures). I will continue to use Mac and PC even though they have higher jitter and clock errors than my CD transports. And even after jitter removal and re-clocking I prefer the CD transports.

Of course this may change if I build a better computer for the audio, not sure what performance increase I will get with a decent sound card instead of spdif direct with this old PC. When more 24/192 music of my liking is available I will go down that route.

There is a danger that computer audio will be hijacked by those to whom cash is a substitute for sound and pseudo science is a replacement for sense. I like good design and great sounds and that is it. I am not going to obsess about bit oversampling jitter creep when listening to music.

yours jitter free, tog

I believe in jitter, but I have yet to see any published figures that put it firmly within the range of audibility when involving well-implentead DACs of reasonably contemporary design. More importantly, I don't hear it. And that is a small wonder, given that expert descriptions of what to listen for range from glare in the treble to dullness in the treble, to the kinds of esoteric audio descriptions that could be attributed to almost anything if they ever rose above the completely subjective.

It would be naive to assume that jitter does not exist. It would be even more naive to assume that most of us, even those of us with pretty highly resolving systems, should not put it way down our list of concerns.

Tim

I think these discussions are ignoring the progress that has been made over the last few years. Firstly DACs that are extremely resistant to jitter were developed and now receiver chips that reduce it to below levels of significance, and if you want more SRC will eliminate it altogether. May I suggest that those interested Google the part numbers of the different DACs available and read the application notes to see how each cope with it.

We're also of the opinion that if a DAC doesn't sound right, a punter will not know why, only that he doesn't like it.

Ash