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Why No World Clock Function For So Many DAC's???

97.89.27.103
Posted on October 30, 2009 at 09:38:04
Dynaudio_Rules
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 I have noticed that very few is any consumer DAC's have word clock abilities yet pride themselves on wanting the best possible audio reproduction. Is it really that difficult to have a Word Clock connection for DAC's?

Certainly DAC manufacturers don't think their DAC's can be improved upon by a external clock...do they?

As far as I am concerned I would never consider buying a DAC without it...


World should be WORD


Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
Internal Clock vs. External Clock, posted on November 4, 2009 at 17:43:27
Dynaudio_Rules
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Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
RE: Why No World Clock Function For So Many DAC's???, posted on October 30, 2009 at 20:40:47
Sunya
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 A DAC needs an Word Clock output which should be connected to the Word Clock input of the transport (or of the sound card if you use a PC as source). The point is to slave the data source to the DAC's clock and in this way the DAC will not have to use a PLL and extract the embedded clock in the SPDIF stream which will be disregarded and will be controlled directly by its low jitter internal clock in the conversion process (where jitter maters).
Exactly what Lessloss does..., posted on October 31, 2009 at 12:43:37
clio09
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 using the CEC TL-51X transport. I own this combo and feel that it is a sound concept. Not sure why we don't see this more in digital designs.

RE: Why No World Clock Function For So Many DAC's???, posted on October 30, 2009 at 16:14:54
John Swenson
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 Are you talking about word clock in or work clock out? Word clock out can get complicated. Sending the clock out is easy. You also need a way to switch over to the internal clock from the receiver generated clock.

Then the hard part, you need some way to select the sample rate. You need some form of UI to select it and display it, and preferably a way to display the sample rate of whats coming in.

Then there is the option of do you make this sample rate selection available on a remote or does the user have to select it with front panel controls?

Its a lot of extra controls to have to explain to someone that just wants to plug it in and listen to music. Thats probably why its not done very often, very few people will use it, and for those that do it needs a lot of extra stuff that is hard to explain to the ones that don't want it. Maybe a separate control panel that is an option for those that want it?

And as Steve mentioned, its only as good as the local clock. For some reason there are several "pro" companies that actually implement a clock out, but the local clock is so bad its almost useless.

As to clock IN, you need a PLL frequency synthesizer to generate the internal clocks from the word clock. This then generates its own jitter and is susceptible to cable type, length, connector all that other fun stuff about digital cables. The one advantage here is that the external clock generator gets to have the UI for specifying the sample rate. IF the local clock is terrible then the external clock might wind up being better, but that is really a put down on the local clock, not that an external word clock is the best way to go.

IF the external clock is an mclock (say running at 11.2896MHz rather than a word clock running a 44.1 KHz) you don't need a PLL which is a much better situation, but you still have to deal with cables and connectors, reflections etc. A properly done local clock is still probably going to be better. A well done local clock (not the best on the planet, but still very well done) can be made for say $20, this is still probably going to have lower jitter than an external mclock even if its a $10K super duper atomic clock. The cable, connectors, board traces etc can add enough jitter to nullify any advantage the external clock has. If the DAC uses a cheap $5 clock then the external clock box could very well be better.

In either case the architecture of the DAC has to be designed so some form of non interface clock can be used otherwise known of as an asynchronous interface of some sort. Now that might be an ASRC with local clock.

If the DAC is of the form - "interface receiver -> clock extracted from interface -> DAC" then there is no place for any type of external clock, in or out.

John S.
RE: Why No World Clock Function For So Many DAC's???, posted on October 30, 2009 at 23:09:27
fmak
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 You have explained things very clearly; thanks for the time you have taken.

This is why I adopted relocking as the strategy, using Big Ben, a Meridian 518, a Digital Lens, and clocks of my own making. I have tried quite a few 'super' local clocks as well, plus feeding word clock back to the transport/processor.

All these schemes sound different and there is no 'best' method. As you say, cables and connectors are important. My UA 2192 has clock cleaning , internal clock, clock output, and clock input modes. UA claims very low jitter like anyone else but clock cleaning sounds as good as the other schemes. For clock input, the single 25 cm 75R BNC cable from the Big Ben or dCS 972 makes a BIG difference.!

Most word clock generators in the pro world sold at sub $500 prices are not very good. Superclocks are even worse. DIY cuperclocks carry big claims, but the output waves shapes are often very poor, highly assymmetric, with very skewed zero points, ground bounce of a high order etc. They can sound very different and or 'ordinary' compared to stock units.

Attention to detail is apparently one of the most important factors in the digital audio world.

RE: Why No World Clock Function For So Many DAC's???, posted on October 30, 2009 at 16:33:18
Dynaudio_Rules
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 Ok I was talking about a word-clock in...

I understand what you guys are saying BUT, I have heard with my own two ears 3 different clocks connected to various pro DAC's. And in each case there was a very noticeable improvement in sound. More coherent, extended with a better presence in every respect to sound stage...much more 3D. The clocks in question are the Black Lion, The Big Ben and an Antelope Audio OCX clock. Now granted, I may be crazy, stupid, and have rose colored ears making me pron to some grandiose placebo affect. But after hearing these impressions I started to Google around and search threads here as well....all of my perceptions are echoed by countless other people. In you guys opinion none of this should be, in fact what I and countless other should be hearing is a degradation in sound not an improvement.



Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
RE: Why No World Clock Function For So Many DAC's???, posted on October 31, 2009 at 13:16:04
John Swenson
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 I don't doubt it. As I said the jitter of the local clock in a fair amount of pro gear is not very good. So using an external clock even with all its problems could still wind up sounding better.

From what I have seen many pro devices use a frequency synthesizer for their local clock so they can easily change the frequency without having to have multiple fixed oscillators. These synthesizers are never all that great. One very famous one that a number of people on this board have freely admits that its local clock has 700ps of jitter, and are very proud of it because its quite a bit less than the competition!

Given this situation a good external clock WILL sound better. But if the manufacturer had used a good low jitter clock in the first place it would be even better than what you can get even with the best external clock.

I understand why they do this, since in real life most studios WILL be using external clocks to synchronize all their boxes, why should the manufacturer bother putting low jitter clocks in the box when nobody is going to be using them?

But thats not the situation in home audio where very rarely are people needing to sync a whole bunch of boxes together.

So you have a choice, find an audiophile company that puts a good clock in the box, has good analog stages etc and is expensive, or go with a pro box that costs a lot less but needs an expensive external clock to get into the same ballpark.

John S.

RE: Why No World Clock Function For So Many DAC's???, posted on November 9, 2009 at 09:55:14
Dynaudio_Rules
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 why should the manufacturer bother putting low jitter clocks in the box when nobody is going to be using them?

I dont want to put words in your mouth....but it seems that if this is true...which I dont doubt. That many pro DAC's esp. those with Word Clock connections might not have the best of clocks inside and in fact will probably have worse clocks than a comparable consumer DAC.



Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
Bingo, posted on November 9, 2009 at 11:15:47
audioengr
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 You are starting to get it. Pro Audio is not a panacea IME.

RE: Bingo.....I WIN!!!!!, posted on November 9, 2009 at 11:27:02
Dynaudio_Rules
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 Interesting....

I mean it makes sense...esp from a business stand point.

And most all studios who use clocks do so to sync up all their digital gear....which is why most word clocks have multiple outs.

Ok, ok....I get it. But that leads me back to square one...:-(



Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
Word-Clock, posted on November 9, 2009 at 13:55:47
audioengr
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 Syncing up all of the clocks only allows the data to move around from one device to the next, ala using a master word-clock generator that feeds all of the other devices. It's not for playback usually and does not really address jitter that well. It's the low jitter of the MASTER CLOCK that really addresses the playback jitter issue.

RE: Pro Audio DACs with good internal clocks, posted on November 8, 2009 at 14:55:29
cfmsp
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"So you have a choice, find an audiophile company that puts a good clock in the box, has good analog stages etc and is expensive, or go with a pro box that costs a lot less but needs an expensive external clock to get into the same ballpark."

Actually, there's another choice - get a pro audio DAC that does have a high quality clock in the box - which will cost considerably less than audiophile equivalent performance due to the much higher margins in audiophile gear.

I recommend the Metric Halo ULN-2 or the Metric Halo ULN-8.

cheers
clay

PS, John, you've got Charlie drooling over here as you damn all the pro audio gear in one feel swoop.
Stop making sense!, posted on November 6, 2009 at 19:39:37
Charles Hansen
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 Many people don't want to hear the truth...

RE: Why No World Clock Function For So Many DAC's???, posted on October 30, 2009 at 23:13:07
fmak
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 The 'improvement' relates not only to clocking, but to the dac and the rest of the set up. Yes, with a good setup, there is great improvement.

Change the cable with anyone of the clocks and you hear the difference as well.

Which clock in your opinion sounded 'best'.

RE: Why No World Clock Function For So Many DAC's???, posted on October 31, 2009 at 07:24:18
Dynaudio_Rules
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 IMO the Antelope Audio clock sounded way better than the others, BUT it was really not a side by side comparison. Different days in different places. So like you said it could have been the associated equipment as well...



Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
RE: Why No World Clock Function For So Many DAC's???, posted on October 31, 2009 at 07:32:02
fmak
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 The difference between the Antelope and the Big Ben is that the former is a clock whereas the latter is a clock/relocker/format converter. The Antelope will not deal with issues of the poor PC aes/spdif output.

Next time, change the word clock cable and hear what happens. Use the Big Ben as a relocker. Admittedly mine has had the voltage regulator changed to a better one. It is really poor that they would use a $1 part with poor performance for this function.

RE: Why No World Clock Function For So Many DAC's???, posted on October 31, 2009 at 11:01:44
audioengr
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 I have modded the Big Ben in past years (I dont mod anymore), adding superclocks and improving data paths etc.. It was good technology then, but things have improved a lot.

RE: Why No World Clock Function For So Many DAC's???, posted on October 31, 2009 at 12:15:12
fmak
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 Why do vendors like yourself continually want to score points? I have explained in response to John Swenson's excellent summary above on word clocks and posted my own experience.

From your past postings, I do not believe that I am any worse than you in judging sound quality. I certainly don't try to sell any approach or any products, and I don't care what have have modded in the past.

I2S, posted on October 30, 2009 at 16:58:43
audioengr
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 Word clock input is not the right way to do it either. What you must understand is that all modern D/A chips dont use word-clock as a clock. They only use it as another "data" signal. This means that even if Word-Clock has low jitter, the other clocks that must be generated from it may not because they must use some type of PLL for a high-frequency clock to lock-onto the low-frequency Word-Clock.

The best way to bring external clocks into a DAC is I2S IMO. Like John S. says above, bring in the Master Clock with low jitter. This is exactly what I2S does. It's beyond me why many companies dont adopt it. Probably either they dont know how to implement it or dont trust it to become an industry standard or both.

There are several I2S standards that have been implemented by at least 5 different companies, all with different pinouts, connectors and even SE versus differential. Making a standard out of this is difficult.

Steve N.

RE: I2S, posted on October 30, 2009 at 23:14:21
fmak
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 Ho, I2S is just as sensitive to cabling etc.

RE: I2S, posted on October 31, 2009 at 11:04:38
audioengr
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 Definitely. I2S cable is critical, just like the AES/EBU or S/PDIF cable is critical. Good ones sound great. Termination, impedance control, construction and conductor metallurgy are all important.

I Wonder What The Makers Of Clocks Have To Say About This, posted on October 30, 2009 at 19:03:30
Dynaudio_Rules
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 And the makers of DAC's with word-clock in abilities.

I need to make some emails to some clock makers...




Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
RE: I Wonder What The Makers Of Clocks Have To Say About This, posted on October 31, 2009 at 11:25:49
Tony Lauck
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 In recording studio applications it may be necessary to use multiple converters simultaneously if more channels are being used than a single converter supports. For obvious reasons, these converters need to be accurately synchronized, and so it is necessary for converters to have clock inputs. It would be best if master clock inputs were used, but the problem is that the master clock rate depends on the converter design. Hence there is a need to specify some clock that is related to the sample rate, which is why pro DACs have word clock inputs.

Some converters also have master clock inputs, which allow multiple converters of the same design to be ganged at potentially better jitter performance.


Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

RE: I Wonder What The Makers Of Clocks Have To Say About This, posted on October 31, 2009 at 11:06:38
audioengr
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 Send an email to audiocominternational.com

They make the best clocks IMO. They start with a sine-wave oscillator. This reduces low-frequency jitter better than a digital clock with a good power supply, which most of the other clocks use.

Steve N.

RE: I Wonder What The Makers Of Clocks Have To Say About This, posted on October 31, 2009 at 12:06:13
fmak
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 The certainly make expensive ones, with no spec and no data.

I do not agree that their products stand up to the claims. I was one of the first to use them.

What evidence do you have that the sine wave output iomproves jitter?. The waveshape of their non sine ones was nothing to write home about either.

RE: I Wonder What The Makers Of Clocks Have To Say About This, posted on October 31, 2009 at 14:46:08
audioengr
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 I have compared a number of clocks. Even the monlithic clocks that I use have identical specs or better than the Superclock4. Guess which one sounds better? The Superclock4. The Ultraclock is even better than that. It's not so much how it measures, its the spectra of the jitter that matters more IME.

I imagine that you tried an older version Superclock. They have improved significantly over the past 3-4 years. Also, when you tried it did you connect it with a 6+ GHz BW coax cable and connector? Did you match the impedance on the board with trace and termination? Did you run a separate power cable or share the ground return? What type of power supply did you use?
RE: I Wonder What The Makers Of Clocks Have To Say About This, posted on October 31, 2009 at 23:04:10
fmak
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 The all important issue is how you compared the clocks; with what equipment and player; with PC output only or with a mixture of sources?

And whether you used your 'best sounding' Foobar 0.8.3 on WDM not ASIO?

RE: I Wonder What The Makers Of Clocks Have To Say About This, posted on November 1, 2009 at 10:17:00
audioengr
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 The clocks were compared using several tracks and USB and reclocker interfaces. It was apples to apples. There was no contest.

My system is extremely resolving too. I hear the differences in offset and format differences between ALAC and AIFF, upsampling etc. Everything is modded.

Steve N.

Question For You, posted on November 2, 2009 at 14:35:31
Dynaudio_Rules
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 Honestly....can you pick out the best sounding DAC based purely on measurements?

Can musicality REALLY be measured?

Accuracy sure, but musicality and accuracy are two different things...And I AM SURE, you try to blend those two in your products.



Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
RE: Question For You, posted on November 3, 2009 at 11:19:45
audioengr
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 "Honestly....can you pick out the best sounding DAC based purely on measurements?"

Not with current measurement techniques.

"Can musicality REALLY be measured?"

Certainly, but not sufficiently using the current measurement metrics.

This is improving however. Those with the deep pockets are making contributions, such as Nordost, who did recently some groundbreaking work on cable measurements and correlation to audibility. This was presented at RMAF.

"Accuracy sure, but musicality and accuracy are two different things...And I AM SURE, you try to blend those two in your products."

It's all about the music and its effect on your brain. It has been proven that music is essential and built-into human genetics, both Genetics and Epigenetics (the chemistry that activates or deactivates genes). My plan is always to optimize every little design aspect as much as I can, as well as thinking outside the box for the concepts. Then when I have something, I do a lot of critical listening. Often it leads to choosing one manufacturer over another, even for the same chip. Lots of tuning also.

Steve N.
Again, moving clocks make jitter, posted on October 30, 2009 at 13:48:33
Gordon Rankin
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 Dyna,

Anytime you have to sync to a word clock input, that means the master clock will have to move with it.

That in itself means there will be significantly more jitter than one that does not offer word clock input.

Thanks
Gordon
J. Gordon Rankin
Huh?, posted on October 30, 2009 at 15:28:22
Dynaudio_Rules
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 No way!

Do I understand you correctly that a DAC with a word-clock input [connected to a clock] will produce more jitter than a DAC without a word-clock input 'not' connected to a clock?

Reason being is because the clock within the DAC needs to sync up with the word-clock.



Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
He's correct, posted on October 30, 2009 at 17:02:46
audioengr
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 For a single clock connector on a DAC, Word-Clock output is the only one that makes sense, and this is a complicated implementation, as described well by John S.

RE: Why No World Clock Function For So Many DAC's???, posted on October 30, 2009 at 12:36:54
audioengr
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 Word Clock output on DAC is interesting ONLY if implemented well and the clock is a very good one. Then it can be excellent. You will be very lucky to get one or both IMO.

Adding the circuitry that automatically switches between an async incoming clock and an internal clock is non-trivial. It has to work whether there is a word-clock cable attached or not.

Once you have a poor clock or clock implementation inside a DAC, there is literally no help for it. Nothing you feed that DAC will sound very good, even really low jitter signals. All you hear is the internal clock. It's like so many upsampling DACs. You just hear the jitter of the upsampling clock. Even if you are lucky and it's implemented well, you are usually stuck with it and cannot upgrade the clock as clock technology improves over time.

RE: Why No World Clock Function For So Many DAC's???, posted on October 30, 2009 at 15:36:26
Dynaudio_Rules
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 "Word Clock output on DAC is interesting ONLY if implemented well and the clock is a very good one. Then it can be excellent."

Of course you realize that statement can be made about DAC's as well or any audio component for that matter. So let's assume the plan is to find a well implemented design and a good quality product.



Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
RE: Why No World Clock Function For So Many DAC's???, posted on October 30, 2009 at 23:28:02
fmak
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 No, audioengr is right, the dac ia all important as well.

There are 'super duppa highly spec'd' dacs that will never sound very good; notably the mid priced ones with 110 kHz resampling and or cheap opamps and coupling capacitors. They also use cinch connecors for everthing.

On a PC, I had the ineteresting experience of using a word clock input module for the RME 968, itself highly praised by JA of Stereophile. The WCM actually made the board sound worse and changing all the Epson XOs to Tent XO plus cleaning up the power supply did nothing.

The 968 simply isn't a very good sounding card.

On the otherhand, the newer 9632 with I think has FGA produced clocking ( I haven't looked too closely) sounds very good and much better (transparency) than my cleaned up Lynx AES16. Both output thru the Big Ben and the same system with different good cables. The Lynx has some hf ringing on the aes output but it is not hf that suffers, rather a less resolving lf which can be the effect of jitter.

Why? Who knows? I do know that the PCs power supply has a major influence as well.

RE: World clock?, posted on October 30, 2009 at 10:36:25
rick_m
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 That would be what, a DAC with a WWVL receiver? There must be 50 things in my house that display time, don't need another.

Rick
RE: World clock?, posted on October 30, 2009 at 10:41:38
Dynaudio_Rules
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 So in your view World Clocks are useless which means you think they can't and don't make a difference [improvement] in sound.

Too bad, your either deaf or never had the pleasure of hearing a DAC slaved to a world clock.



Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
No... Rick is alluding to your usage of "World" instead of "Word". N/T, posted on October 30, 2009 at 10:47:48
carcass93
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 N/T

Oh....Let Me Got Fix That, posted on October 30, 2009 at 10:51:50
Dynaudio_Rules
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 .

Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
RE: I should have resisted..., posted on October 30, 2009 at 12:53:27
rick_m
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 ... but it's been a slow morning, the market's bad, etc. I beg your forgiveness.

For home audio using LAN makes the most sense to me. I don't care exactly when the music starts playing as long as it does it consistently once it gets going. Having the client playing away and just sending out for another packet when the buffer gets down seems ideal to me. I've been looking at the Squeezebox stuff but I think I'm too old for it, I'd just as soon that my stereo not engage in 'social networking' and folks that keep changing the names of their applications annoy me. I also don't want to run complex SW on the server side.

What's this have to do with the word clock? Well, if the client only does audio maybe I can arrange to run it and the D/A off the same clock. It wouldn't be as grandiose as a world clock however, rather more of a closet clock...

Regards, R.

RE: I should have resisted..., posted on October 30, 2009 at 13:14:06
Dynaudio_Rules
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 I agree LAN does seem to be the way to go....

Oh and its ok about the word thing....the market has been bad for the past few days. Normally that would be a good thing if I had money to buy...:-)



Scrutiny Strengthens The Truth and Breaks Down Lies 音楽は天国と地球のかけ橋
RE: I should have resisted..., posted on November 3, 2009 at 08:08:01
regal
 These soundcards with wordclock input use a PLL to do the timing, there is very little jitter reduction because the clock is compromised by the PLL.

RE: I should have resisted..., posted on November 6, 2009 at 14:42:09
Tony Lauck
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 If the DAC uses its master clock to run the conversion and if it sends the master clock to the sound card, then the sound card will send back samples at the correct average rate. A small buffer in the DAC will eliminate any jitter coming from the transport. Hence, any jitter in the soundcard PLL will have been eliminated by the DAC.

It may be that the DAC doesn't work that way. If so, then it is a poor design. It makes no sense to generate a clock locally, send it out a cable, take it back in another cable and then use the doubly degraded clock rather than the pure original.


Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

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