Digital Cable Differences

[lucey]

I'm left wondering why or how these interaction artifacts have been known for 10+ years ... but it's not common knowledge to more people who are generally in the know?

Why was this info not posted over and over again, where audiophiles were being bashed? Was it more fun to bash them than to admit that they're actually hearing something change from the effect of the S/PDIF on DA? S/PDIF is the common cable for home hi fi, and as Dan is saying it's the least robust, so it seems they were (mostly) right all along.

[24-96 Mastering]

Originally Posted by lucey

I'm left wondering why or how these interaction artifacts have been known for 10+ years ... but it's not common knowledge to more people who are generally in the know?

Why was this info not posted over and over again, where audiophiles were being bashed? Was it more fun to bash them than to admit that they're actually hearing something change from the effect of the S/PDIF on DA? S/PDIF is the common cable for home hi fi, and as Dan is saying it's the least robust, so it seems they were (mostly) right all along.

Phew, I'm kinda scared to post in this thread. And I realise those questions are probably rethorical, but I think it's worth trying to answer them anyway:

I think audiophiles have a hard time getting credibility because they have a tendency to over-generalise observational evidence to the point where it becomes religion. That usually triggers the sceptics to be just as over-generalising.

There's never a fruitful discussion on topics such as these. No audiophile wants to hear _why_ a digital connection can make a difference and how that technical shortcoming could be avoided altogether. They want the cable to make a difference. They want the actual cable to be the problem and the fix. And to be honest, I think often, they actually prefer to be unscientific so that the aura of the unexplainable remains. Makes people (or products) feel special... and makes them such easy targets for sceptics.

If you have a discussion where dozens are screaming aye and dozens are screaming naye, those that are saying "it depends" or are suggesting the original question isn't the right one to be asked usually won't be heard. And I think that had Mr. Lavry not posted his explanation of the phenomena under his real name, it would have gone largely unnoticed.

[lucey]

Originally Posted by 24-96 Mastering

If you have a discussion where dozens are screaming aye and dozens are screaming naye, those that are saying "it depends" or are suggesting the original question isn't the right one to be asked usually won't be heard.

Sounds logical, except some who parse info pretty well didn't hear it either. Are you saying you knew that "it depends on the DA" all along? Because in all these years, I've heard a lot of aye and nay, and never it depends.

[Bob Olhsson]

Most "common knowledge" comes from advertising-financed publications.

You'll never hear a peep about incompetent product design from those folks.

[24-96 Mastering]

Originally Posted by lucey

Sounds logical, except some who parse info pretty well didn't hear it either. Are you saying you knew that "it depends on the DA" all along? Because in all these years, I've heard a lot of aye and nay, and never it depends.

I believe I've heard or read "it depends on the DA" a lot. Granted, maybe that's a post yr 2000 thing, when around then (I think) manufacturers started advertising jitter resistance specs as a feature.

[Dan Lavry]

Originally Posted by pinwale

Dan, when discussing digital formats and susceptibility to the issues brought up you said "It is not the format itself, it is the physical properties that matter."

.

I do need to clarify a point. When I said that it is not the format, I was referring to the subject XLR, optical or RCA as means for transmission. I was talking about voltage (power), balanced transmission, noise rejection....

When it comes to the mechanism that Hawksford discovered, the format has a lot to do with it, as the title of his paper indicates - "Is the AES/EBU digital format flawed".

Theoretically, a digital signal has vertical transitions from say 0V to 1V. If you set the detection threshold at 0.25V or at 0.9V, you get the same detection time.
But in practice, there is a finite rise time (slop). Say the transition from 0V to 1V takes 10 nsec. If the threshold is set to 0.5V, you have 5 nsec detection delay from the start of the slop. If you set the threshold of detection to 0.6V, the detection time is 6nsec and that is 1nsec longer....

So when there is a rise time slop (in practice there always is), the relationship between the threshold and the signal has a time element to it (which may or may not matter).

If you are trying to detect a word clock, which is a simple 101010101010 having a 10 nsec slop and 0.5V is OK. If you move the threshold to 0.6V, you are also OK because all that happened is an overall 1nsec shift in time.

But to transfer digital audio, the signal is no longer repetitive. It can be 1101001001010111, and now you have "long durations" of 1's and zero's and "short durations". (Two consecutive 1's is longer then a single 1 followed by a 0). That by itself is still not a problem. But when a "long duration of 1" moves the whole signal down vertically, and a "long duration of 0" moves the signal up vertically, the threshold "meets" the signal on a different point in time on the rise time slop.

What causes the signal to move up and down (following the duration of short and long 1's...)? It is AC coupling that is the culprit. With AC coupling, give the signal enough time, and the DC level will settle somewhere. The average of 101010101010... is 1/2. The long term average of 111111000000 is also 1/2 but for a while it "favors" 1 then it starts moving towards 0. So the AC coupling "does a job" on the "short term DC average", it wobbles the signal up and down... that is a jitter mechanism.

And it does have a particular sound. As I mentioned the MSB has the most impact because it lives next to the longest time duration cell (the "sample marker"). A lot of people think that analog audio is totally disconnected (not correlated) from the digital content of 1's and 0's, but such is not the case. In most audio signals, the MSB has the same frequency as the fundamental. That does matter, because when the MSB finds its way into modulating the sound (in this case by means of jitter), the audible impact is much more deterministic than some random noise or random jitter.

For example: Take a 1KHz triangle wave between -1 and 1. When the signal is above 0 the MSB is high. When the signal below 0, the MSB is low. Now assume that a high MSB moves the detection later in time by 1nsec and a low MSB moves it earlier by 1 nsec. Guess what? You just added a square wave to your triangle wave! True, the square wave is lower amplitude, but the distortion is far from random...
If the signal is a 1KHz sine wave (instead of triangle), you still get an addition of a 1KHz square wave...

Perhaps I am being too detailed. I hope I am not losing too many readers.

Lucey is correct to say that I do not know everything. But I do know that the timing issue is not about the cable alone. There are 2 simultaneous causes, rise time (high frequency limitations) and droop (low frequency limitations, AC coupling).

The cables are not the only rise time limiting factors. The cables have nothing to do with the low frequency limitations. What you want form the cable is wide bandwidth (good flat response to high enough frequency). The cable will pass DC so the low frequency portion of the problem is elsewhere (in the gear itself).
In many practical cases, the rise time limitation is dictated by something other then the cable and focus belongs elsewhere. If you signal is say 5nsec rise before you connected a cable, and the cable rise time is say 1nsec (350MHz bandwidth), the "combined rise time" is 5.1nsec and the cable does not count much. But a 35MHz cable (10nsec rise) with a 5nsec rise makes for combined 11.18nsec thus the cable becomes the limiting factor.

From a quantitative standpoint, for cable length of a few feet, I would expect the major part of the problem to be the AC coupling (the gear itself). For very long cable runs (100 meters, 300 feet), the cable may be a major contributor. Of course those are just very general guidelines. Personally, if someone is having a problem with a 6 foot cable, I would tend to look for another cause, not the one I discussed above.

Again, short cables tend to have wide bandwidth. Long cables may be a problem. The factors that limit the cable bandwidth is a whole subject by itself. Optical links is yet another subject...

It is easy to ignore extreme nasty remarks, everyone can tell an extreme way out hostile post. But I do have to limit my posting time. I have some work to do...

Regards
Dan Lavry

[lucey]

What about a digital interface that runs on DC with a wall wart? Pros or cons there?


Bob I don't read mags about gear, I'm talking about arguments/conversations online that you and DC and others have seen and been a part of. I can't understand why until now digi cable tone was discussed and argued without clarification in such a way that when this thread began anyone with a shred of insight would have known the reason for the result. And say what you will about the technical shortcomings of the designs and the marketing blah, blah. blah .... the audiophiles were generally speaking, CORRECT all along. Cables matter. Is that not the case? That is certainly not old hat. And yet a few people seem to be saying this is all old hat.

As Arf said, the fact that files were posted was new. And most people here, I'd wager, have learned something. So where have those with the information been keeping it all this time, and why wasn't the validity of SPDIF tonal changes in hi-fi not presented more often by anyone who knew all along, to clarify the reality, assert their authority, and to stop the (misplaced) bitching about the audiophiles and the cable sellers to then talk about the reality?

[Dan Lavry]

Originally Posted by lucey

What about a digital interface that runs on DC with a wall wart? Pros or cons there?


Bob I don't read mags about gear, I'm talking about arguments/conversations online that you and DC and others have seen and been a part of. I can't understand why until now digi cable tone was discussed and argued without clarification in such a way that when this thread began anyone with a shred of insight would have known the reason for the result......... to clarify the reality, assert their authority, and to stop the (misplaced) bitching about the audiophiles and the cable sellers and to talk about the reality?

Lucey,

While you are the one talking about the need to understand cables, I was certainly surprised that you at first did not even bother to read my post due to some general negative comment I made about many audio cable makers.

It would be good if, as you suggested, everyone including yourself stays on the subject of cables. Instead, some of your focus is on attacking, first me as a "know it all" and now you are jumping all over Bob and DC. I want to know what Bob and DC have to say.

Again, I too have an issue with a huge amount of cable related BS out there. And that fact should not a cause for ignoring the message and talking about the messenger (re-read your last post).

Dan Lavry

[24-96 Mastering]

Originally Posted by lucey

the audiophiles were generally speaking, CORRECT all along. Cables matter. Is that not the case?

That claim really depends on specific circumstance and can't be generalised. Imo it should say: Digital cables can matter if the D/A is susceptible to jitter. I'm really out of my league here though, so if I'm now generalising, please someone chime in.

That is certainly not old hat. And yet a few people seem to be saying this is all old hat. As Arf said, the fact that files were posted was new. And most people here, I'd wager, have learned something. So where have those with the information been keeping it all this time, and why wasn't the validity of SPDIF tonal changes in hi-fi not presented more often by anyone who knew all along, to clarify the reality, assert their authority, and to stop the (misplaced) bitching about the audiophiles and the cable sellers and to talk about the reality?

Much of this is still focussing on the wrong question to be asked, imo.

Instead of focusssing on whether or not cable can change tone, it should be asked WHY it can or can't change tone in a specific setup.
The resulting conclusion should be that, ideally (these days at least), cable should not change tone and if it does (and if that concerns the user), one shouldn't go shopping for different cables, one should rather exchange the piece of equipment that is susceptible to jitter.

I expect cable makers to have little interest in exploring the why's or to educate their customers. Of course they'll say that their $1000 cable always sounds "more musical". I find that very questionable, whether or not they know better. Let them be ridiculed for either being uneducated in their supposed field of expertise or for intentionally misleading their customers. If they make such generalised claims, that is, and of course, not all of them do.

All that aside, this thread, as you say, is very interesting and I'm learning a lot of new stuff. How signal correlated jitter comes to be, for example. And the sound files are indeed interesting. Nothing is ever an old hat, there's always something to be learnt.

[space2012]

Originally Posted by 24-96 Mastering

That claim really depends on specific circumstance and can't be generalised. Imo it should say: Digital cables can matter if the D/A is susceptible to jitter. I'm really out of my league here though, so if I'm now generalising, please someone chime in.

Pacific Microsonics, is known by the best ears in the industry to be the best converter ever made.
if Pacific Microsonics is susceptible to jitter.
that means it can improove with an atomic clock.

if your AD/DA is not suceptible to jitter,
it has an internal FIXED jitter. they use the lowest jitter clock possible they could build to reclock the signal with SRC or Memory Buffers.
and those AD/DA converters will not improove with Atomic Clocks. that does not mean they are better.

its like RME hdsp DDS, another jitter reduction method.
sounds like crap!, when you turn DDS off, and use a better external clock,
everything sounds amazingly better.
but if you turn DDS on with ext.clock, the DDS worsens the better ext. clock to RME SteadyClock(TM) levels.

if you want to improove your AD/DA some day and your AD/DA has jitter reduction methods, that cannot be turned off. you cant improove your AD/DA.

for example: a cheap Roland MMP-2 can have more clock accuracy if clocked with an atomic clock, verry hi quality cables and clean AC power, than a Lavry AD/DA10 or any other AD/DA with jitter reduction methods that cannot be turned off.

only the analog circuit design and chip brand and model "chip design" are left to fight for a better sound. becouse in the clock depepartment is a lost battle.

if you want to know how important is a clock,
just get a digi96io or any other latest generation AD/DA that is suceptible to jitter,
and clock it with yamaha dsp factory ds2416, or emu 1820m or the clock from an old DVD consumer player. old vhs/dvd samsung combo players.

record, mix and master.
then get the best clock you can, and...
record, mix and master same thing, but with a better clock, cables, clean ac power.
bounce and Burn CD-r with the 2 files.
and hear them in every place you can.

[Schnert]

Hey, that thing looks like a spacetroll!

Originally Posted by lucey

Why was this info not posted over and over again, where audiophiles were being bashed? Was it more fun to bash them than to admit that they're actually hearing something change from the effect of the S/PDIF on DA? S/PDIF is the common cable for home hi fi, and as Dan is saying it's the least robust, so it seems they were (mostly) right all along.

Not really. Cable design becomes more of a factor the longer the runs are. What lenghts of spdif cable do audiophiles normally use? A couple of feet?

[Dan Lavry]

[QUOTE=space2012;4082231]ok, let me get this right,
you:

A) atomic clocks are worthless, and people that bought one are fools.

Not all are fools, some fell for bad marketing.

B) your converters are jitter free, better than 100 atomic clocks.

That is real ridicules! I could not do worse if I tried.

C) hi quality cables are not needed, the audio files in this thread is a collective hallucination.

I did not say that high quality is never needed. I am into defining what quality is needed.

D) the best ears in the industry bought an atomic clock becouse they got fooled by the marketing BS, not what they hear. they are easy to fool.
becouse Atomic clocks are worthless and your converters are jitter free.

Actually, a lot of the best ears in the industry are NOT using atomic clocks. You are making things up you can not back up.

E) everybody got fooled or everybody is a fool.

A fool is the person that when presented with IRON CLAD TECHNICAL REASONS chooses to ignore it and try to go on the attack. Can you think of anyone to fit that slot?

F) Audio does not require great accuracy.

Did I say that? I did not. I make great accuracy gear. Your bring up accuracy and your statement is much less then accurate, it is totally made up.

G) you are polite to me becouse you are afraid to loose the respect of people here.

I am not afraid. While very tempting, the forum rules do not allow me to call you an idiot. So I did not.

Dan Lavry

[MichaelPatrick]

If I understand aright, I hear Dan say that accuracy in audio is about good timing within an audio session.

I don't know that much about these things, but I once did computer work for a company that makes high end clocking for measurement, military, broadcast, etc., and I learned some things hanging around those guys:

Quartz crystals have a purer sine wave than atomic clocks and much lower phase noise.

Atomic clocks are used to discipline a crystal, correcting their tendency to drift over long periods of time. Cesium clocks are more stable in this regard than Rubidium, by about 100x. A hydrogen maser is the best of all worlds, but it'll cost you several hundred thousand USD and may not fit very well in the studio.

Atomic clocks are usually purchased for applications that need immunity from long-term drift when a Stratum 1 or other such reference (i.e. GPS) cannot be guaranteed to provide the needed level of discipline. Note that long-term drift is not a practical issue for audio, and there is no need to sync with global time.

Originally Posted by space2012

ok, let me get this right,
you:

A) atomic clocks are worthless, and people that bought one are fools.
B) your converters are jitter free, better than 100 atomic clocks.
C) hi quality cables are not needed, the audio files in this thread is a collective hallucination.
D) the best ears in the industry bought an atomic clock becoause they got fooled by the marketing BS, not what they hear. they are easy to fool.
becouse Atomic clocks are worthless and your converters are jitter free.
E) everybody got fooled or everybody is a fool.
F) Audio does not require great accuracy.
G) you are polite to me becouse you are afraid to loose the respect of people here.
tutt
WTF!

[Nordenstam]

Originally Posted by space2012

Pacific Microsonics, is known by the best ears in the industry to be the best converter ever made.
clearly Pacific Microsonics is susceptible to jitter.
that means it can improove with an atomic clock.

Try to reread the thread. The PM ADC is the master clock in the setup. The issue is the performance of the DAC in the setup. If I understod this correctly, performance improved when the DAC was running on internal clock - as it was designed to do.


You wrote this to Dan Lavry: "B) your converters are jitter free, better than 100 atomic clocks." and later "keep dreaming. low quality cables affect not matter if they are 1ft."

From an earlier post in the thread:

Originally Posted by Lupo

Did some tests here too, using an SPDIF line to feed a Lavry DA10. Compared to the original, the recorded files all nulled within .1dB. The only way I could find a significant diffference was to use a long stretch of cheapest sort RCA interconnect and a bunch of those badly made and unshielded RCA<>JACK adapters. With two active GSM phones(on different networks), right on top of the adapter barrels, drop outs occured. Could not replicate the drop outs using normal cables.

Originally Posted by space2012

if you want to improove your AD/DA some day and your AD/DA has jitter reduction methods, that cannot be turned off. you cant improove your AD/DA.

You can't easily improve on a well functioning design.

Originally Posted by space2012

for example: a cheap Roland MMP-2 can have more clock accuracy if clocked with an atomic clock, verry hi quality cables and clean AC power, than a Lavry AD/DA10 or any other AD/DA with jitter reduction methods that cannot be turned off.

Don't forget that the Roland will in all cases be limited to what happens with the external clock when it enters the device. The roland clock reciever circuit will probably fare worse than a well designed DAC in all cases of external clocking.

[24-96 Mastering]

Originally Posted by lucey

24-96 why not let people shop and talk about cable as they please? What business is it of yours or mine? It's not for us to condemn them for their tone quest.

Brian, you misunderstood, I have no interest in policing how others shop or talk about cable. I have no agenda here.

[Schnert]

Originally Posted by space2012

Ah, Youtube. Berkeley go home!

[Dan Lavry]

Originally Posted by lucey

So Dan, now you're telling me how I should read your posts? Who do you think you are exactly?

You are right. I should not care what you read. I put some time into a post directed to you, and I did care. It was a waste of my dear time. I no longer care what you read or not read.

Bye

Dan Lavry

[lucey]

Originally Posted by 24-96 Mastering

Brian, you misunderstood, I have no interest in policing how others shop or talk about cable. I have no agenda here.

Ah, okay thanks. I read a lot of "should" in your post and thought you were on Dan's judgmental bandwagon there for a second.


This thread is about what happens with in particular, S/PDIF and a DA. And anything that relates to same.

Pretty please...

[jayfrigo]

Well, this has been useful. Could we maybe try to keep one or two of the really knowledgeable posters around? Several have already been scared off, and it really diminishes the value of the resource. It looks like we may have to have another short-term moderation tightening. People are welcome to disagree all day long, but without the vitriol.