Will clocking MOTU 828 mkI to Mytek Stereo192 improve DA of 828?

[nas]

I plan on upgrading my front end with a Mytek Stereo192 AD and will have a MOTU 828 mkI slaved to it through the SPDIF. I'm bypassing the 828 converters and just using it as a FW audio interface. My question is will clocking the 828 to the Mytek improve the sound quality of the 828's DA because it is locked to a more stable clock? is this something that is quite noticeable?

[nas]

hello... hello... hello... is there anybody in there? just nod if you can hear me ... is there anyone at home? come on.. now....

[Roc Mixwell]

Originally Posted by nas

I plan on upgrading my front end with a Mytek Stereo192 AD and will have a MOTU 828 mkI slaved to it through the SPDIF. I'm bypassing the 828 converters and just using it as a FW audio interface. My question is will clocking the 828 to the Mytek improve the sound quality of the 828's DA because it is locked to a more stable clock? is this something that is quite noticeable?

If you have both units in question; why not test it and report back your findings.

[nas]

nope don't have both units just the 828.. that's why I'm asking. I am planing on purchasing the Mytek ADC and want to see if it will improve my DA as well until I can afford to upgrade to a dedicated MYTEK DAC later on.

[Roc Mixwell]

Originally Posted by nas

nope don't have both units just the 828.. that's why I'm asking. I am planing on purchasing the Mytek ADC and want to improve my DA until I can afford to upgrade to a MYTEK DAC later on.

The Mytek has a better clock. But its a better converter anyway, so that is to be expected.

[guard dawg]

I have a motu traveler clocked by a mytek 96ad and the da on the motu has improved the image is wider and better defined.I also have a mytek96 da but there is no comparison to the motu traveler, i have a benchmark dac and i find the traveler clocked to the mytek a bit better but not as smooth as the benchmark.

[nas]

Originally Posted by guard dawg

I have a motu traveler clocked by a mytek 96ad and the da on the motu has improved the image is wider and better defined.I also have a mytek96 da but there is no comparison to the motu traveler, i have a benchmark dac and i find the traveler clocked to the mytek a bit better but not as smooth as the benchmark.

Thanks for that info - that's exactly what I was wanting to know. thumbsup

[theblue1]

Originally Posted by nas

I plan on upgrading my front end with a Mytek Stereo192 AD and will have a MOTU 828 mkI slaved to it through the SPDIF. I'm bypassing the 828 converters and just using it as a FW audio interface. My question is will clocking the 828 to the Mytek improve the sound quality of the 828's DA because it is locked to a more stable clock? is this something that is quite noticeable?

There is an extraordinary amount of outright misinformation and pervasive misunderstanding of this issue.


Slaving a given converter to an external clock source virtually always tends to increase jitter (irregularity of sample timing).

Slaving to an external clock source does not remove a supposedly 'inferior' clock circuit from the process -- indeed, the converter's internal clock circuit is STILL the source of internal timing -- but NOW it must do the much more difficult job of continually trying to maintain sync with the external clock by a phase locked loop.

This is more difficult than simply keeping good internal time. And -- crucially -- it tends to increase jitter, which means decreased sample accuracy (the samples are measured at the wrong point in time).


So, why do so many people have this strange notion that trying to sync to an external clock can improve sound?

Good question. Much of the problem relates to a marketing campaign by a certain mid-high level maker of converters and external clocks (external master clocks can be helpful in big rigs, since even thought he best option is often to use the clock in the 'lead' converter for the master, it can be more convenient to have a central clock with multiple i/o options).

This campaign featured a number of celebrity endorsers who claimed their rigs "sounded better" simply from being slaved to Brand X (or should I say Brand A?) master clocks. The company says that THEY never claimed that but that they have many endorsements for people who say it's so.

But that company has since backed away from some of the more outrageous claims and now says that those who want to buy one of their master clocks simply looking to improve the sound of a converter should simply buy one of their converters instead. (Which makes considerably more sense, at least if one thinks their [quite well-liked] converters are worth the moderately substantial buy-in.)


Anyhow, if you want to read a LOT about the issue, there's a mammoth thread that involves many heated exchanges between digital design legend Dan Lavry and some other heavyweights arguing againt a number of "true believers" and even some representatives from the unnamed manufacturer above:

PSW Recording Forums: Dan Lavry => Proper word clock implementation


But... why do so many people think their converters "sound better" if the jitter is almost certainly greater?

Both Dan Lavry and Digidesign's tech staff (in a white paper they wrote on the issue) have suggested that these folks are either fooling themselves (precious few seem to have pursued double blind ABX testing) or that these folks may simply like the distortions produced by jitter.

Digidesign white paper on external clocking and jitter: http://akmedia.digidesign.com/suppor...er_J_33269.pdf

[nas]

Originally Posted by theblue1

There is an extraordinary amount of outright misinformation and pervasive misunderstanding of this issue.


Slaving a given converter to an external clock source virtually always tends to increase jitter (irregularity of sample timing).

Slaving to an external clock source does not remove a supposedly 'inferior' clock circuit from the process -- indeed, the converter's internal clock circuit is STILL the source of internal timing -- but NOW it must do the much more difficult job of continually trying to maintain sync with the external clock by a phase locked loop.

This is more difficult than simply keeping good internal time. And -- crucially -- it tends to increase jitter, which means decreased sample accuracy (the samples are measured at the wrong point in time).


So, why do so many people have this strange notion that trying to sync to an external clock can improve sound?

Good question. Much of the problem relates to a marketing campaign by a certain mid-high level maker of converters and external clocks (external master clocks can be helpful in big rigs, since even thought he best option is often to use the clock in the 'lead' converter for the master, it can be more convenient to have a central clock with multiple i/o options).

This campaign featured a number of celebrity endorsers who claimed their rigs "sounded better" simply from being slaved to Brand X (or should I say Brand A?) master clocks. The company says that THEY never claimed that but that they have many endorsements for people who say it's so.

But that company has since backed away from some of the more outrageous claims and now says that those who want to buy one of their master clocks simply looking to improve the sound of a converter should simply buy one of their converters instead. (Which makes considerably more sense, at least if one thinks their [quite well-liked] converters are worth the moderately substantial buy-in.)


Anyhow, if you want to read a LOT about the issue, there's a mammoth thread that involves many heated exchanges between digital design legend Dan Lavry and some other heavyweights arguing againt a number of "true believers" and even some representatives from the unnamed manufacturer above:

PSW Recording Forums: Dan Lavry => Proper word clock implementation


But... why do so many people think their converters "sound better" if the jitter is almost certainly greater?

Both Dan Lavry and Digidesign's tech staff (in a white paper they wrote on the issue) have suggested that these folks are either fooling themselves (precious few seem to have pursued double blind ABX testing) or that these folks may simply like the distortions produced by jitter.

Digidesign white paper on external clocking and jitter: http://akmedia.digidesign.com/suppor...er_J_33269.pdf

wow! - this is very interesting. I have indeed heard the exact opposite numerous times but have yet to try it out myself. Once I acquire my new ADC I will give it a try and report back what I "prerceive" to sound better - to slave or not to slave? Of course in the end it will be somehwat of a moot point as I plan on also upgrading my DAC as well... but it will be interesting to give it a try. In the meantime I will check out those threads you posted - thanks for that thumbsup

[theblue1]

Like I said, a lot of misinformation and confusion on this topic.

I would commend anyone who wanted to go beyond what I've written (which is basically just a sum-up of the info I've collected on this issue over the last few years from expert sources) to follow through the links in my previous post.


With regard to checking it out yourself, this is a reasonable idea -- but only if you institute a rigorous double blind testing regimen (neither the test-giver or -taker knows the actual identity of the sources being compared).

Why?

Can't we trust 'recording engineers' to be able to use their ears?

In a word, maybe not. (OK, two words.)

Since the late 19th century, the scientists who study human perception have noted that expectation and perceptual bias play a big part in the perception of sound.

Not only did they find that a test-taker who knew the source of two given perceptual phenomena he was comparing would bring his own bias and perceived pre-knowledge to the task -- but that even when the test-taker didn't know the answer that a test-giver who did could subtly (or not so) influence the test-taker's answers. (One reason why the so-called "Pepsi Challenge" was thoroughly bogus.)

So it became standard procedure to insist on a double-blind methodology in order to neutralize the chances of bias/contamination.

Now, many audiophile types -- not a particularly well-grounded-in-science lot to begin with -- will go into conniptions when one mentions double blind test methodology -- because, when push comes to shove, many of the tweaky little unscientific toys they have (Clever Little Clock, wooden cable lifters, green markers, etc) tend to make no difference when put through rigorous perceptual testing.

It's also very pertinent to remind folks here (who really should know this already) that when listening to even the best monitors in a moderately well-treated room a difference in listening position of only a few inches can make as much as 12 or more dB of difference in perceived loudness between two frequencies of the same playback level.

Turn your head a few degrees, and the tone will tend to shift. Our brains use these shifts in perceived sound in order to 'self-locate' in our environment and, unless one listens carefully, he may not even be aware of these changes in perception. But they can be large, even in a well treated room. And they can be huge in an untreated acoustic environment.

[Roc Mixwell]

Originally Posted by theblue1

Like I said, a lot of misinformation and confusion on this topic.

The only way to figure this out is to try it yourself in your studio. End of story. Buy a Microphone if you don't get it. End of story.

[theblue1]

Originally Posted by Roc Mixwell

The only way to figure this out is to try it yourself in your studio. End of story. Buy a Microphone if you don't get it. End of story.

Roc

Do you think I don't get it?

And what on earth does a mic have to do with anything? We're talking about whether or not slaving a given converter to an external clock source increases jitter in that converter.


Your buddy Fletcher decided to have a go at me on this issue a while back. He didn't offer much in the way of meritorious or factual argument and I doubt you will, either. From HC: Lo and behold, I can hear my converters after all - and they sound like crap! - Page 2 - Harmony Central Musician Community Forums

[Roc Mixwell]

Originally Posted by theblue1

Roc

Do you think I don't get it?

And what on earth does a mic have to do with anything? We're talking about whether or not slaving a given converter to an external clock source increases jitter in that converter.


Your buddy Fletcher decided to have a go at me on this issue a while back. He didn't offer much in the way of meritorious or factual argument and I doubt you will, either. Lo and behold, I can hear my converters after all - and they sound like crap! - Page 2 - Harmony Central Musician Community Forums

I was speaking in general terms and not directing this at you. You say there's a lot of mis information going on. Reading posts won't solve this for any one. How are we to believe posts and 3rd party speak. You have to listen for yourself, and if you don't hear anything, don't buy a master clock, buy something else that will benefit your studio. That was my point. Not a bash, or a flame, just the truth.

[theblue1]

Ah... sorry. I've been in a few tussles on this topic... it's kind of second nature.




With regard to hearing for oneself, it's certainly an important aspect of the whole evaluation process.

But while the auditory system (ears/brain) is the most important tool a recordist has -- and certainly the most sophisticated and complex -- it is not ideal for making detailed comparisons between different sources or for taking objective measure.

And that is why double blind ABX testing is crucial for really determining subjective preference between two similar sound sources.

Perceptual scientists have realized for well over a century that preconceptions influence perception tremendously and for that reason double blind testing is a bedrock of preference evaluation.

So, if double blind testing shows that one does, indeed, prefer one sound source over another, no one can argue with that preference.


However, it's nonetheless important to remember that when we're evaluating the performance of a converter that there are some very important objective measurements that inarguably reflect the accuracy or lack thereof of the conversion process, and one of the most fundamental and critical of these is measurement of jitter (irregularity of sample timing). If one prefers a sound that is measurably less accurate, ultimately, it's a personal decision -- but it's important in public discourse to keep the personal/subjective and the universal/objective carefully in their own boxes.

[guard dawg]

All I can say is that i saw and improvement the sound stage is wider switching back to the motu clock was so narrow it felt like mixing in a shoe box .like Roc said the only way is to find out for your self,but trust me you would not be disappointed

[theblue1]

Originally Posted by guard dawg

All I can say is that i saw and improvement the sound stage is wider switching back to the motu clock was so narrow it felt like mixing in a shoe box .like Roc said the only way is to find out for your self,but trust me you would not be disappointed

Here's one possible explanation for the perception of a wider sound stage in the stereo image deriving from slaving to an external clock:

Lower sampling accuracy means greater divergence from the accurate signal in every channel. Greater divergence from accuracy means more difference from channel to channel -- and that means a less coherent stereo image.

This ain't rocket science.


Use your ears, sure.

But also use your brain.

[Roc Mixwell]

Originally Posted by theblue1

This ain't rocket science.

Actually, it is, but you don't need to understand any of it to hear a change, with ALL KNOWN VARIABLES ACCOUNTED FOR. Anyway, I'm not going to carry on here. I just don't think you're going to be able to prove anything in either camp without being in the same room with each other. And even then results are inconclusive between testers. I've seen it happen, but best believe, I'm not going to degrade my experience no matter what.

[nas]

I'm always interested in discovering or learning new things about audio, equipment, engineering, music etc... and there is much valuable information to be digested and utilized, however, ultimately I believe it is really a judgment call. Yes a double-blind test can help even the playing field a bit provided that several other factors are also taken into consideration as was mentioned earlier. But at the end of the day whether I can hear enough of a difference to warrant a purchase - sometimes worth several thousand dollars - I believe is a subjective issue, regardless of how "objective" the parameters of a given test or shoot-out are.... and this is also taking into account that the higher you go the more you will start to experience diminishing returns.

I simply do not want to over-think it... If I like what I hear, if I feel it's worth the additional $$, and I know it is from a reliable and reputable manufacturer... then I buy it and forget about it. After all ... I'm much more interested in getting creative and have my tools "get of the way" so to speak so I can get on with it. My ultimate objective is that simple... and I agree it certainly doesn't hurt getting good feedback, assimilating valuable information, experimenting and ultimatley drawing one's own conclusions through experience.

[theblue1]

Originally Posted by Roc Mixwell

Actually, it is, but you don't need to understand any of it to hear a change, with ALL KNOWN VARIABLES ACCOUNTED FOR. Anyway, I'm not going to carry on here. I just don't think you're going to be able to prove anything in either camp without being in the same room with each other. And even then results are inconclusive between testers. I've seen it happen, but best believe, I'm not going to degrade my experience no matter what.

I have a [day job] client who is into racing sailboats. One of the members of his team is a brain surgeon. People are understandably fascinated.

When folks ask about it, he tells them, "Brain surgery? Well... you know... it's not rocket science."




FWIW, Roc, I'm not trying to prove anything. What folks prefer is what they prefer. (At least when they actually know they prefer it. See rant on double blind testing.) I'm just trying to make sure that folks have the generally accepted facts on the increased jitter likely to result from slaving a converter to an external clock source.*

(Of course, setting one master clock source and slaving all other clocks to it is absolutely necessary when yoking multiple converters together. Still, it can be better, in some respects, even there, to use the internal clock of one of the converters as the master; since, in that circumstance, at least one converter will not have internal jitter increased by attempting to maintain sync with an outside clock source.)


*BTW, it's not that difficult to get confused about what a certain external clock maker says about their jitter correction technology. If one is less than rabbinical in his approach to some of that company's representatives' comments, one can get the false impression that they are claiming their jitter correction technology can somehow clean up the bad internal clocking of converters slaved to it. However, all a dedicated wordclock generator can really do is put out accurate, pristine clock signal, nothing more.

It cannot pass any positive voodoo down the clock wire. A given dedicated clock may well be able to clean up incoming clock signal, removing jitter and making it a better clock signal -- and when necessary that ability should be golden -- but that juju is internal. What it passes out to slaved clients is, at best, simply good, clean clock signal. If those slaved converters have bad clock circuits that can't keep their own internal time it's very likely that they will also do a bad job of the much harder task of keeping sync with an outside clock signal. No matter how clean that external clock is.

[jamwerks]

TheBlue1,

I'm pretty sure that it was in that thread that Dan Lavery stated that external clocking might be better if the internal one is of really low quality. I myself asked him that question. Not 100% sure but that's my recollection.......

[theblue1]

Originally Posted by jamwerks

TheBlue1,

I'm pretty sure that it was in that thread that Dan Lavery stated that external clocking might be better if the internal one is of really low quality. I myself asked him that question. Not 100% sure but that's my recollection.......

It's my recollection (and I revisit parts of that thread from time to time to refresh myself) that he allowed that that was a possibility but that it was quite unlikely for the reasons outlined above (which I have cribbed shamelessly from Mr Lavry).

I'm more than happy to correct myself, if I've erred, I think that's important. But I'm pretty sure I've got the gist of Lavry's reasoning here.


As I noted indirectly, one place where the kind of juju that a good external clock can really come in handy is in a complex rig where one is forced to slave to a dicey clock source (for whatever reasons)... In that case, the abilty of something like a Big Ben to correct for jitter and clean up incoming clock and then pass that "de-jittered" signal down the line would, indeed, be valuacanble. But, typically, I suspect most folks with a smaller rig would use a properly terminated daisy chain, or, if the rig is more complex, perhaps a dedicated clock either at the front of a daisy chain or in a one-to-many routing.

[Dan Lavry]

Originally Posted by theblue1

It's my recollection (and I revisit parts of that thread from time to time to refresh myself) that he allowed that that was a possibility but that it was quite unlikely for the reasons outlined above (which I have cribbed shamelessly from Mr Lavry).

I'm more than happy to correct myself, if I've erred, I think that's important. But I'm pretty sure I've got the gist of Lavry's reasoning here.


As I noted indirectly, one place where the kind of juju that a good external clock can really come in handy is in a complex rig where one is forced to slave to a dicey clock source (for whatever reasons)... In that case, the abilty of something like a Big Ben to correct for jitter and clean up incoming clock and then pass that "de-jittered" signal down the line would, indeed, be valuacanble. But, typically, I suspect most folks with a smaller rig would use a properly terminated daisy chain, or, if the rig is more complex, perhaps a dedicated clock either at the front of a daisy chain or in a one-to-many routing.

The only "possible argument" I ever heard in favor of external clocking is that the AD had a poor internal clock. I pointed out that this argument is unlikely, and here is why:

In order for the argument to stand, one will first have to find an AD with TWO clocks.
1. A poor fixed frequency internal clock oscillator circuit for internal clocking.
2. A better quality variable clock oscillator circuit for external clocking.

It is unlikely that the same designer would use a poor clock for a fixed frequency internal operation, and a better variable clock for external. A fixed crystal is inherently more stable then a pullable frequency oscillator.

But even if that extremely unlikely assumption were to take place, when using external clocking, other factors come into play, and I did mention them. There is the additional PLL circuitry, a cable with termination tolerance, separate grounding between clock and AD and more.

Take a good clock circuit and connect it with a reasonably short and direct path to an AD. This is the best you can ask for. The whole notion that the SAME clock circuit is a better4 clock just because it is in another chassis, further away is bogus! So even conceptually there is no reason to accept that external clocking is better. Add to it the real life factors (PLL, cable, termination, grounding…) and the argument really falls apart.

Given the above, and much more that I already stated in past posts here and elsewhere, it is sad to see so many people fall for BS that serves commercial interests at the expanse of audio quality. I am not against external clocking when it is needed. I too provide external clocking capabilities, and I do my best to make external clocking be as near as possible in quality to my internal clocking. But that is very different then claims that external clocking is better then internal.

Sadly, arguments such as “try it, you will like it” often trump principles of physics and iron clad logic. Converter technology is very complex and demanding. Clocks are a low tech technology relatively to converters. If your conversion is not good enough, get a better converter, not an external clock to drive a lesser converter.

Regards
Dan Lavry