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Author Topic: Proper word clock implementation  (Read 104256 times)

Nika Aldrich

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Re: Proper word clock implementation
« Reply #210 on: March 24, 2005, 07:51:03 pm »

Dan,

You keep talking about how Apogee is out of line with their marketing that cables can "induce jitter" and that there's, therefore are better because they are "low jitter cables."  You keep discussing the word "induce" as a straw man argument, discussing how cables can't "induce" and therefore Apogee's argument is bad.

Please tell me, where does Apogee discuss cables "inducing" jitter in their marketing text?  

What I read in Apogee's marketing of "low jitter cables" is that their cables provide greater jitter rejection.  Why is this reading erroneous?

Nika
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danlavry

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Re: Proper word clock implementation
« Reply #211 on: March 24, 2005, 09:42:37 pm »

Nika Aldrich wrote on Fri, 25 March 2005 00:51

Dan,

You keep talking about how Apogee is out of line with their marketing that cables can "induce jitter" and that there's, therefore are better because they are "low jitter cables."  You keep discussing the word "induce" as a straw man argument, discussing how cables can't "induce" and therefore Apogee's argument is bad.

Please tell me, where does Apogee discuss cables "inducing" jitter in their marketing text?  

What I read in Apogee's marketing of "low jitter cables" is that their cables provide greater jitter rejection.  Why is this reading erroneous?

Nika


Nika,

This time I have done the footwork looking for quotes through previously written posts. Next time please do it yourself. And so here is the outcome of my footwork below:

Max said:

Finally, let it be clear to the end user that you are deceiving them with another semantic argument when making reference to our cables. Of course cables don't lower jitter, but cables do create jitter, some more than others. Apogee's Wyde-Eye cable creates less jitter artifacts than other cables. We did not call it the "jitter free" cable or even the "jitter reducer", so this blatant attack is a deception.


I say:

You see, Max said “cables do create jitter”. He then decided not to continue but the “Apogee regulars” picked up the argument by pointing to a particular section in Julian’s paper. It was Logichead 3-23-05. That is where Julian uses the phrase Cable induced jitter in context to AES data link.

Of course right after I explained that cables don’t make jitter, he came back with the quote from Julian’s paper as if it is some kind of a bible, beyond Maxwell’s laws of Physics….

So Max said that my comments were deceitful because cables do create jitter. The few “pro Apogee guys, no matter what”  found a poor phrase “Cable induced litter” and of course some still do not get that there is no such thing as cables generating jitter, that cables do not induce jitter, and that Julian paper was not referring to what I am talking about which is ultra low jitter word clock cable, where higher bandwidth may not always be a plus.

There are a lot of people in audio that do not understand jitter but know it is a “concept” and it is “bad”. So one can sell stuff by marketing all sorts of products as “low jitter”.

From the Word Clock Cable literature at the Apogee website one finds this misinformation:

"The 110 ohm cable maintains the exclusive double shield system of gold foil and braiding for improved clarity and RF rejection. Discerning high-performance audio enthusiasts can now enjoy the benefits of this ultra-low jitter and temperature
controlled cable, which has become the leading choice of cable for mastering engineers and the professional audio industry in general since its intoruction in 1993."


Since you and Max worked together in sales at Sweetwater it is possible that you got “numb” to all sort of claims. I am an engineer and of course think of the consumers in a different way than a salesman. Obviously, an innocent person may believe that he/she will have less jitter by buying a cable that is touted to have ultra-low jitter. The words temperature controlled as you well know, sound impressive to a non-technical person. I will show you an example of an innocent victim: Logichead really believed that cables induce jitter. This belief was based on a misuse of one word in an otherwise relatively ok white paper that does not apply to work clock.

Dan Lavry
Lavry Engineering, Inc.

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Nika Aldrich

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Re: Proper word clock implementation
« Reply #212 on: March 25, 2005, 07:23:31 am »

Dan,

First, to correct your spreading of misinformation, Max, nor anyone else at Apogee, has ever worked in sales at Sweetwater.  

Second, the quote you refer to is clearly referencing 110ohm cable, which is AES/EBU cable, which even YOU say can "induce" jitter according to Hawksford, Dunn, et al.  That quote clearly does not refer to 75ohm wordclock cable, does it?  And even IF the website were referring to 75ohm wordclock cable (which it very clearly is NOT) the Apogee website information would STILL not be incorrect, for the wordclock cable could REJECT more jitter than other cables (from EMI, RFI, etc.)  and thus indeed be a "low jitter" cable.  Yes?

It seems that Max's quote that "cables can create jitter" was correct in regards to AES/EBU cable, and that their website says the same thing.  You seem to be extrapolating from these quotes from Max that ALL cables can create jitter, including wordclock cables, but Max says no such thing.  He also doesn't say that Cat5 cables can induce jitter, that romex can induce jitter, or that aircraft cable can induce jitter.

But let's go a step further.  I will say here that ALL cables can induce jitter - it just depends on what you use the cable for.  If you transmit pure square waves on the cable (word clock pulses, like BNC cables are TYPICALLY used for) then the cable itself will not "induce" jitter.  It can certainly help "reject" jitter, however.  If, on the other hand, you use the cable to transmit more complex digital data, such as SPDIF, AES/EBU, ADAT format, MADI, or whatever else, and you intend to extract the wordclock from that signal then indeed the cable CAN "induce" jitter.  Since 75ohm cable can be used for both wordclock AND for SPDIF, it is indeed fair to say that coax cable CAN "induce" jitter, depending on what it's used for.  Apogee sells their 75ohm cable in various terminations for wordclock AS WELL AS formats that are sensitive to cable-induced jitter, such as MADI, video applications, and SPDIF.

I'm sure that, in light of this, you would agree that Apogee should go back and clarify their website and more correctly say that BOTH their 110ohm and their 75ohm cable are "ultra-low jitter cable," rather than just their 110ohm cable as in the quote you referenced last night?  After all, we want complete and accurate information, yes?  

Nika
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danlavry

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Re: Proper word clock implementation
« Reply #213 on: March 25, 2005, 01:04:57 pm »

Nika Aldrich wrote on Fri, 25 March 2005 12:23

Dan,

First, to correct your spreading of misinformation, Max, nor anyone else at Apogee, has ever worked in sales at Sweetwater.  

Second, the quote you refer to is clearly referencing 110ohm cable, which is AES/EBU cable, which even YOU say can "induce" jitter according to Hawksford, Dunn, et al.  That quote clearly does not refer to 75ohm wordclock cable, does it?  And even IF the website were referring to 75ohm wordclock cable (which it very clearly is NOT) the Apogee website information would STILL not be incorrect, for the wordclock cable could REJECT more jitter than other cables (from EMI, RFI, etc.)  and thus indeed be a "low jitter" cable.  Yes?

It seems that Max's quote that "cables can create jitter" was correct in regards to AES/EBU cable, and that their website says the same thing.  You seem to be extrapolating from these quotes from Max that ALL cables can create jitter, including wordclock cables, but Max says no such thing.  He also doesn't say that Cat5 cables can induce jitter, that romex can induce jitter, or that aircraft cable can induce jitter.

But let's go a step further.  I will say here that ALL cables can induce jitter - it just depends on what you use the cable for.  If you transmit pure square waves on the cable (word clock pulses, like BNC cables are TYPICALLY used for) then the cable itself will not "induce" jitter.  It can certainly help "reject" jitter, however.  If, on the other hand, you use the cable to transmit more complex digital data, such as SPDIF, AES/EBU, ADAT format, MADI, or whatever else, and you intend to extract the wordclock from that signal then indeed the cable CAN "induce" jitter.  Since 75ohm cable can be used for both wordclock AND for SPDIF, it is indeed fair to say that coax cable CAN "induce" jitter, depending on what it's used for.  Apogee sells their 75ohm cable in various terminations for wordclock AS WELL AS formats that are sensitive to cable-induced jitter, such as MADI, video applications, and SPDIF.

I'm sure that, in light of this, you would agree that Apogee should go back and clarify their website and more correctly say that BOTH their 110ohm and their 75ohm cable are "ultra-low jitter cable," rather than just their 110ohm cable as in the quote you referenced last night?  After all, we want complete and accurate information, yes?  

Nika



Dan,

First, to correct your spreading of misinformation, Max, nor anyone else at Apogee, has ever worked in sales at Sweetwater.

OK. I will take it back. I thought everyone that worked in Sweetwater was in sales or sales support. He was the ProTools expert at tech support was he not? I call it sales, but I can take it back.

In fact, I saw his comments on the Sweetwater forum about big Ben “Call it what you want, but the difference is not subjective”.
   
   http://www.sweetwater.com/forum/showthread.php?s=7601e1c4241    f8c6123aa04414285de93&threadid=6715&perpage=15&p agenumber=4

Not subjective means what? It means objective. That goes against the present marketing which is about subjective listening!

Second, the quote you refer to is clearly referencing 110ohm cable, which is AES/EBU cable, which even YOU say can "induce" jitter according to Hawksford, Dunn, et al.

Wrong. I got that quote from their SPECIFIC WORD CLOCK CABLE description! (Go to Apogee site, click on store and nevigate to Word Clock Cable (not AES cable) or click on the link below)

That quote clearly does not refer to 75ohm wordclock cable, does it?

You just pointed out another error in their marketing. They are selling 110 Ohms cable under their WORD CLOCK.  

   http://www.digitalriver.com/dr/v2/ec_MAIN.Entry10?xid=28122& amp; amp; amp;    amp;PN=1&SP=10023&V1=331437&DSP=&CUR=840& ;amp ;amp ;amp ;PGRP=0&CACHE_ID=0

So is that another BIG ERROR in the marketing department? Or are they selling 110 Ohm cables instead of 75Ohms. to people that use 75Ohm termination? Why did not go and see for yourself? You don’t even see that you are defending an error. Your bias is showing.

And even IF the website were referring to 75ohm wordclock cable (which it very clearly is NOT) the Apogee website information would STILL not be incorrect, for the wordclock cable could REJECT more jitter than other cables (from EMI, RFI, etc.) and thus indeed be a "low jitter" cable. Yes?

No. you are getting off track! I am not going to get into a pissing match about one word or another.

The issue is not about a single phrase such as “ultra low jitter word clock” cable. It is not about a single phrase “temperature controlled cable” (which you selectively ignore!). It is not about some people saying (or not saying) that they like what they hear. Apogee is trying to make it into an issue of the ear against the technology, and it is not that either.

All of this back and forth started as a technical discussion. My recent posted graphs are what technical is about, not all of these words. It was not intended to become a “David vs. Goliath” of audio. Remember our other run-ins where you kept me busy with your daily inputs.

I do my best on this forum to educate about the technical, to give theory and info that will help individuals themselves ask questions have a better understanding of some aspects of audio. So I got into talking about clocks and AD’s.

Apparently what I said “did not sit well” with Apogee. Apogee engineer Lucas stated his position on this forum. I accepted it. Amazingly enough, Apogee did not. Someone’s requested farther dialog recently, and I did not even reply. Then Max came in and said that Apogee did not participate in a dialog, as if Lucas had not said what he did. That was the point where I renewed my comments, including the word clock cable comment.

One does not make a judgment of a product based on one piece at a time. One looks at how the pieces interact together. So let me show you how the later cable comment ties into this thread:

I can assume that Apogee and I agree that less jitter is a good goal. I say so all the time. Their stand is indicated by the fact that they are selling an ultra low jitter cable. We all agree that jitter is bad.  

That by itself provides enough grounds to reject and some crazy suggestions by some (trying to explain the impossible) that adding jitter explains the sonic improvements when driving an AD externally via a cable.

I stated that generally speaking, internal clock is better whenever possible. Apogee said otherwise.

Here is what technology leadership means:

If Max is right and cables make jitter, Apogee should be telling people that buy their box to keep connections short. Apogee should have made some effort to QUANTIFY jitter (learn how much) say 100 foot cable adds to a their clock box BEFORE getting into an argument with me about internal vs. external clocking. Even if my other un answered arguments are wrong (they are not wrong), that one by itself needs a TECHNICAL answer. They chose a marketing answer – ultra low jitter cable.

If Max is wrong and cables do not make jitter (and that is the case), then we have a company that claims technology leadership but is not a technology leader. I used to tolerate it, until Max and Lucas came here storming with impossible claims, trying to “create impressions” that they represent the 21st century and I should be disregarded as a 20th century type. I defended my position well. I was forced to back Apogee “up against the wall”. It was about telling people the best way to use their gear.

It is not about taking a single phrase to a product. It is about technical leadership vs. the claim for technical leadership. It is about how marketing leadership is willing to step all over what is technically correct, disregarding what is really good for the industry and the customers. And Goliath can and does get away with it. With huge exposure, advertising resources, claims to be the best in the world in print all over, with year after year tech awards that are about name recognition and do relate to advertising money, not technology.

I am not a King Kong with overseas manufacturing. We make everything in the U.S. I take time to help uplift the industry by running a forum and Apogee had to come here and try to muck with my honest efforts, stopping at nothing. Did you see what Max wrote about me at Fletcher site? He was not at Apogee when it was in start up mode and his facts are all screwed up.  

But they are losing that argument because they are technically so very wrong! They may continue to sell a lot of gear but they lose the technical arguments here. I have to assume the reason they sent you here is because no one with technical chops would back them up. So why are you here? I call it Chutzpa.

Your tone is inappropriate and disrespectful. Such technical people and better people do exist, you are not one of them. I already saw you are not up to par technically to come up against me. You argued and made some terrible mistakes on this forum, don’t you recall. struggling with the issue of relating dynamic range to bits, which was remarkable for someone writing a book about the subject. There was that idea of common clock for AD and DA to cancel jitter, with you suggesting a flash audio AD and DA which was extremely indicative of your lack of hands on and any design experience. There were some comments about filters that left a lot to be desired…
.
As far as I am concerned you are a recent graduate with no design experience and you share something in common with Apogee. Commercial ties? Maybe so, maybe not so. But you both are into creating the impression of technical leadership. They are not talking or answering anyone’s questions.

Once again you are taking too much of my time. I cannot accept you coming in here as if you were some technical guru, splitting hair about words, and misstating facts. I certainly did not agree that cables induce jitter.


Dan Lavry
Lavry Engineering
www.lavryengineering.com
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Fletcher

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Re: Proper word clock implementation
« Reply #214 on: March 25, 2005, 02:41:49 pm »

danlavry wrote on Fri, 25 March 2005 13:04



You just pointed out another error in their marketing. They are selling 110 Ohms cable under their WORD CLOCK.  

     http://www.digitalriver.com/dr/v2/ec_MAIN.Entry10?xid=28122& amp; amp; amp; amp; amp;      amp;PN=1&SP=10023&V1=331437&DSP=&CUR=840& ;amp ;amp ;amp ;amp ;amp ;PGRP=0&CACHE_ID=0

So is that another BIG ERROR in the marketing department? Or are they selling 110 Ohm cables instead of 75Ohms. to people that use 75Ohm termination?


Apogee may very well be full of shit... and none of us should ever stop making sure that each and every manufacturer [be that manufacturer Apogee, Lavry, Digi-Design, Studio Projects, or Behringer] can support each and every claim they make 100% with scientific evidence.  

Subjectivity aside [we are in ways a community of artists that employ technology for artistic purpose] anything less than 100% supportable/factual claims must be challenged at all expense, within reason... with that in mind I quote the immortal words of Albert Einstein [who I'm told was a hell of guitar player] "As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality."

In this [one] particular case Apogee isn't full of shit [doesn't mean they're not somewhere else, just not in this case], the link to the store on Apogee's site is general description of all their cable products, not any one specific cable product.

"Digital River" is what's known as a "fulfillment house".  A fulfillment house, in this case "Digital River" hasn't the slightest remote clue of anything technical.  The purpose of this fulfillment house is to warehouse hardware,offer it for sale via the internet, take orders, process those orders and ship those orders.  For all anyone at "Digital River" knows or cares these things could be TV's, Ginsu Knives, or talking bears.

Why Apogee has chosen to employ this fulfillment house to hawk their wares is a mystery... and personally I think it's rather unnecesary [I would think that now wouldn't I Twisted Evil ] and frankly, counterproductive... but it's not my place to tell them what to do.

The "official" Apogee cable description page http://www.apogeedigital.com/products/wydeeyecables.php does indeed have the correct product descriptions and designations.

At this point, as one of the administrators here at R/E/P, I have to say that this 14 page thread has run it's course.  All threads over time and multiple pages will tend to mutate from the original call and response, this one has done just that.

At this time, this thread will be locked.

I wholeheartedly encourage the various participants of this thread to begin new "sub threads" that focus specifically on the myriad of concepts and concerns that began and were continued through a couple hundred posts scattered over 14 pages.

As is the charter for Dan's forum, subsequent threads that will grow from this thread will be based firmly in science, and that all statements made in these subsequent threads can be backed up with empirical data.

On behalf of the staff and management of R/E/P I would like to thank each and every participant for their time and knowledge in these areas, and sincerely hope to see several productive threads spawned from the seed planted here.

Peace.



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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch.  
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

Sin x/x

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Re: Proper word clock implementation
« Reply #215 on: August 21, 2006, 11:50:54 am »

It's very simple to me:

A properly engineered converter will sound the same, no matter what cable or master clock you use.
It should accept data from the serial input signal and regenerate its own clock.
Audible differences simply mean poor design.
Things like that simply don't belong in a professional environment.

The questions about cable jitter are therefore total nonsense.

Keep up the fight Mr. Lavry.
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Fletcher

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Re: Proper word clock implementation
« Reply #216 on: August 21, 2006, 07:09:50 pm »

Sin x/x wrote on Mon, 21 August 2006 11:50

A properly engineered converter will sound the same, no matter what cable or master clock you use.


Yes, a properly engineered converter will sound like a properly engineered converter, the sound of a converter is very much dependent upon that converter's clock, and jitter can indeed be induced by cabling.

An external master clock can make an inferior converter design [see RME for details] sound better.  An external master clock can make an entire system sound different [see your sense of aesthetic for "better or worse"].

I put a Big Ben on my RADAR V system.  I thought it fucked up the sound.  I put the RADAR V clock on my Lavry "blue series" converters [which I use for most mixes] and thought it fucked up the sound.  We use Apogee AD and DA-16x devices on our DAW... which have a similar clock to the Big Ben.  We clocked those units from both the RADAR V and the Lavry "Blue Series" [at different times of course] and found those clocks fucked up the sound [in our opinion].  However, all of these different converters and different clocks were different sounding... there were differences within our own camp as to which sounded better and which sounded worse.  Each of our staff has their own opinion.

My personal opinion is to use each converter working on it's own internal clock, but YMMV.

Peace.
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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch.  
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

Sin x/x

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Re: Proper word clock implementation
« Reply #217 on: August 22, 2006, 01:37:54 am »

A properly engineered DA-converter should have at least 2 separate pll's.

One for the FM data separator. This pll is much to jittery to drive the DAC directly, but unfortunately most manufacturers use just this one. And now you will hear cable and masterclock differences.

The other PLL (or a couple in series) you need to drive the DAC itself. This PLL gets fed by the PLL of the FM data separator. This PLL should have high damping and regenerates the clock signal without any jitter.

If this is the case jitter has no effect on the analog audio signal.

The jitter of the AES/EBU signal should be of cause within certain limits. Otherwise the first PLL can't lock. But if the jitter is within these limits and you have a properly engineered converter, everything is fine: No jitter at all.

Its analog to error correction, If the errors are within certain limits you can retrieve the original signal.
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danlavry

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Re: Proper word clock implementation
« Reply #218 on: November 16, 2006, 01:04:57 pm »

The "Proper word clock implementation" thread is back after a year and a half.




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Dan Lavry
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crm0922

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Re: Proper word clock implementation
« Reply #219 on: November 20, 2006, 02:45:26 am »

Maybe Apogee will come back and answer the (still unanswered) questions posed to them:

Quote:

I. QUESTION: WHICH SOLUTION PROVIDES LESS JITTER AT THE AD LOCATION?

1. A REASONABLE FIXED CRYSTAL
2. BIG BEN DRIVING A CLOCK INTO A CHASSIS EQUIPPED WITH A PLL VIA A 10 FOOT CABLE?

II. QUESTION: CAN ONE EVER CANCEL OR REDUCE A RANDOM NOISE AT ONE END OF A CABLE WITHOUT KNOWING WHAT KIND OF JITTER ACTIVITY IS OCCURRING AT THE OTHER END?
(can one cancel, remove or reduce the receiver and PLL noise, some of it unknown, some totally random, by driving it with a clean low jitter clock? Driving it with any clock?)


Can't wait.

Chris
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Lucas van der Mee

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lavry
« Reply #220 on: November 21, 2006, 01:31:57 pm »

The answers to those questions we have given several times before in this thread. But to make it easy for you and not have to search for it I’ll say it again:

Jitter at the converter chip will be lower, in most cases, when clocked to internal. There is no doubt about that, no mystery, we never claimed anything else. However, we do say a number of things that are beyond this question.
1.   Big Ben is an excellent solution if you need a master clock. It is low jitter and offers a lot of features the competition does not have.
2.   If you need to clock to a jittery source, for instance a SPDIF output of a computer or a commercial cd player, having the Big Ben re-clock the data first, will very often improve the sonic and MEASURABLE quality of the converter used. The amount of improvement is all dependent of the quality of the PLL circuit of said converter. In other words, the better the PLL, the least improvement will be noted.
3.   For this one I will be quoting Max, because he put it so well:

“Yes, Jitter is a deficiency that causes a certain type of distortion to the signal. However, the ear, being a non-linear device with respect to frequency, will not hear all jitter the same. It is very easy to create a scenario whereby two signals can be induced with jitter, one of which has significantly more jitter than the other, but sounds audibly more ACCURATE to the ear. The distortion due to jitter on the one with more jitter can be relegated to frequencies that are entirely out of the human audible spectrum in various ways, whereas the other can have far less jitter, but at frequencies that are much more audibly apparent.

It is certainly possible to design an external clock in such a way that the increased amount of jitter that results will have less of an audible impact than the internal clock by itself. For this reason one cannot claim that an internal clock will always be more accurate - merely that it will theoretically always have less jitter. There is a significant difference between the two, and the testimony we have been seeing on the market and in our own testing with respect to Big Ben over the last few years certainly attests to this.”

I would like to add to this: There are numerous examples in technology, where we find that an actual reduction in performance of one parameter can lead to a perceived and sometimes actual improvement, in others. A good example in audio is dither, (noise shaped especially). By adding dither we actually reduce the dynamic range, yet we improve the perceived noise floor by masking the annoying noise of rounding errors.

My last word on this topic is, people do perceive more than science can explain. Our senses are intrinsically subjective, however the more experienced we become, the more we train our perception, the more OBJECTIVE we can become and obviously, your mileage may vary.

Lucas van der Mee
Sr. Design Engineer
Apogee Electronics
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Lucas van der Mee
Sr. Design Engineer
Apogee Electronics
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