Clocks

[rich]

Hi all!

 

In my quest for knowledge of all things audio, I came across the concept of clocks. External clocks, internal clocks..and I understood a little bit about it.

 

Can anyone explain what it is exactly? And what the benefits of an external clock are?

 

Also, I know I am a newbie and that the users of this forum are most often professionals, and i think it would be cool to have some sort of special section explaining in detail the concepts of audio, from source to speaker, with schematics and glossary. This website is a reference and I (humbly) submit this idea to the community.

 

So thank you for all i've learned here!

 

[rich]

So either no one here knows what a clock is, or no one gives a shit about explaining. Guess it is better to discuss about how practicing voodoo will give you a better sound, or argue with Teresa about how the mini-jack output of her MacMini will give her much better sound than a High-End CD player...

 

I'm outta here, thank you.

 

[4est]

Or maybe we all thought you just had some reading to do first...

 

[Audio_ELF]

Wow.. I've just discovered this great new website. It's called Google and various county specific versions exist including www.google.co.uk which allows you to search the WHOLE of the Internet.

 

Typing "Digital Audio Clock" gave me several pages of results which allowed me to find all about how clocks relate to digital audio...

 

In seriousness, read some general information THEN if you have specific questions ask them in a forum!

 

Eloise

 

[wgscott]

The function of an external clock is to continuously flash 12:00 while you watch video tapes on your programmable VCR.

 

[rich]

....I come here with a positive, eager-to-learn attitude and what i see is elitist people who think they know so much and yet can't take 10 minutes to explain a concept that is hard to grasp (or at least for suckers like me)...but who will happily argue for a week with a troll talking nonsense about HD music via mini-jack and insulting "the idiots who listen to CD format"...

 

 

I had big respect for this forum, and didn't find any in return.

 

 

[bleedink]

I did the exact same thing you did when I first came to the site and no one would answer my very very broad questions that I didn't bother to research first.At first I thought people were just being 'elitist'...I didn't realize that people come onto the forum all the time asking very broad questions and expecting everyone to answer all their questions without them doing the work...You need to do some work yourself, then come onto the forums and try to seek clarification. If you come at the members on here respectfully and patiently, as well as having done SOME research and reading the FAQ pages and such, I guarantee you will get an entirely different response. Trust me, several people on here wouldn't even talk to me after my first post. Don't go that route. Folks on here are great if you are sincere and do some homework on your own as well. Respect is a two way street and if you are positive and eager to learn you won't let a little set back like someone not answering your question (which is a bit broad) in what you consider due time deter you from learning. I sure didn't. I kept trying to learn and join in until I garnered a bit of the respect I lost with my first post which was very similar to yours....just a bit of advice...YMMV of course...But I have found the more I put into the site the more I get out of it. Chris even suggested that this site was not for me when I presented an attitude similar to yours. And he was right. Don't burn your bridges before you've found a river you want to cross!

 

[The Computer Audiophile]

Rich - Clocking is a very difficult concept for most people including myself. I suspect this has something to do with the lack of answers to your original question.

 

A kind follow-up or more specific question may get you better results than insulting all the CA contributors who freely volunteer their time to improve other's computer audio experiences.

 

 

 

[firedog]

Rich-

 

I'm guessing that most of us don't fully understand it and we know it.

 

None of us want to give an incorrect answer.

 

In addition, a good answer would be very long and involved and involve quite a time commitment.

 

One of the pros would need to answer you, and your question is too broad to merit an answer here.

 

[Paul R]

I'm kinda sorry you feel you were being ignored. You asked a very complex question that actually takes a lot of time just to lay the foundation to explain.

But, in a nutshell -

 

Clocking is all about making two or more things do the same or complementary actions at as close to exactly the same time as is possible.

 

In very broad strokes, you can think of the inaccuracies in timing as degrading the sound. A specific instance of timing inaccuracy is what we call "jitter."

 

That is of course, a very broad generalization. A bit of thought and good research will help give you an idea of how complex and important timing is in digital audio. Perfect timing would give you perfect synchronization, which would mean much closer to perfect signal transfer between components.

 

Ergo- better sound.

 

-Paul

 

 

[rich]

I apologize if people felt insulted. I felt insulted too and that is why I was so aggressive. I will narrow my search and come back with more detailed questions and hopefully earn back the respect i lost today.

 

Peace

 

 

 

 

 

[Jud]

Here's what clocks are for (the responsibility for any errors is entirely my own):

 

Are you familiar with the way CDs, for example, work? There are "pits" (very small depressions in the surface) and "lands" (the surface between the pits) which represent 1s and 0s in "digital" (i.e., binary) code. The binary code in turn represents the analog (music) waveform. Computer audio works the same way, except there we're talking about 1s and 0s in a computer file rather than physical pits and lands.

 

In digital audio, especially "high resolution" audio, these 1s and 0s go by extremely fast. Just to get the 1s and 0s right, the timing at the DAC (digital to analog converter) stage has to be very, very good. Fortunately virtually all DACs do have the necessary timing accuracy. But even timing errors that are minute fractions of what's necessary to get the 1s and 0s right - errors on the order of nano- or even picoseconds, called "jitter" - will produce some distortions in the analog music signal.

 

It is therefore extremely important when decoding to analog to reproduce correctly the timing by which the signal was encoded to digital, down to billionths of a second . This is done by means of extremely accurate "clocks" (oscillators).

 

If there's something you don't understand in the above, please ask.

 

[Pacific.Digital]

Your interesting question addresses one of the core, critical areas of everything relating to digital and computer audio. There is an informative white paper on this subject at the Grimm Audio www.grimmaudio.com Web site. http://grimmaudio.com/whitepapers/Picoseconds%20or%20ppm.pdf

 

Basically, the accuracy of a clock, meaning what time is it, in, say, 100 years, is actually not very important. What really matters is the short-term stability of the clock, generally described as phase noise. For high-quality clocks, the phase noise over a particulat bandwidth, say 1 Hz to 100 kHz, will be in picoseconds, possibly femtoseconds. Jitter is another way of expressive phase noise. Very low frequency phase noise, from 0.1 to 1 Hz, seems to be very important for realism, presence and soundstaging.

 

Most USB-S/PDIF interfaces don't even have published phase noise or jitter specs, which often relates to the fact that their performance in this regard is poor. Rad the reviews in Stereophile and 6moons. Often the designers don't have the equipment or technical knowledge to make sure measurements in the first place. Until quite recently, good phase noise analyzers cost from $40 to $100K and up.

 

Using an excellent external reference clock may improve the performance of even high-quality DACs which have a word clock input. In addition to the Grimm CC-1, the Black Lion Audio Micro Clock MK2 has very good phase noise measurements.

 

So you're asking exactly the correct question: Why are clocks important, and how does one evaluate them? This is a beginning. If you check Wikipedia, there are some good discussions about phase noise and jitter.

 

[wgscott]

Sorry, that was a second-hand joke.

 

[spacejay]

i had a problem with linux and couldn't get to grips with some of the concepts (i wouldn't class myself as a thicko)and no-one would help me out. so i logged on as a woman and people were so very helpful.

i agree with everyone here that it is better to find stuff out for yourself though and if you can't understand something state clearly that despite your research you still can't understand.

 

 

 

[wgscott]

That is a brilliant idea! I worry about the psychiatry bills, but I'm going to try this and see if I can get an irritating iTunes problem answered on the Apple BB.

 

[AudioDoctor]

 

[Moses]

The most helpful explanation I know is here:

http://www.thewelltemperedcomputer.com/KB/Clock.htm

 

(the author sometimes posts here). Everything else on that site is also wonderful.

 

John

 

[bleedink]

they are changing genders to get answers to their important questions! An eclectic bunch, audiophiles...