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Auralic LEO GX DAC Clock Review

lszomb

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#41
Thanks Amirm, I was under the same impression. However, with that, shall I say following statements made by dCS:

"In a digital audio system, samples must be accurate in level and time but jitter, which exists in all digital systems, can result in timing errors in these samples, causing the analogue signal to be reconstructed inaccurately."
Ref: https://www.dcsltd.co.uk/products/vivaldi-clock/

are completely trash talk? I knew there are many big names also produce masterclock for Hi-Fi.

It is just hard to believe they all try to sell sneak oil to us.

Some other useful testing reference: https://www.soundonsound.com/techniques/does-your-studio-need-digital-master-clock


Well, this is what he did:
View attachment 46727

That is half a millisecond of jitter which is HUGE! I measured 0.5 nanoseconds in recent measurement of the minidsp udio-8 and called that bad. This is 1000 times more jitter! Even with that, he got a tiny, tiny blip.

Here, we are talking about network and USB playback anyway. In both cases the input is a data pipe and its jitter is immaterial. THe clock would be locally generated by the DAC since the input is not synchronous.
 
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amirm

amirm

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Thread Starter #42
I suspect the device needs to warm up and stabilize and that might be responsible for the long boot period.
Long boot is the OS. After that, there is a one hour countdown for the clock heater.
 
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amirm

amirm

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Thread Starter #43
hanks Amirm, I was under the same impression. However, with that, shall I say following statements made by dCS:

"In a digital audio system, samples must be accurate in level and time but jitter, which exists in all digital systems, can result in timing errors in these samples, causing the analogue signal to be reconstructed inaccurately."
Ref: https://www.dcsltd.co.uk/products/vivaldi-clock/

are completely trash talk? I knew there are many big names also produce masterclock for Hi-Fi.
It is poor language. As I explained, in audio we don't care about absolute timing. If your song takes 362 seconds or 362.1 seconds, it will absolutely not make a difference. What makes a difference is if each audio sample is output at a slightly faster or slow time and keep changing (jitter). I test for this in my DAC reviews and with some rare exceptions, I can't find jitter that rises to the level of audibility. The fix for this is better implementation of the DAC and its local clock, not some external clock.

As a matter of pure engineering, there is no way to make an external clock as good as an internal one. The cable will degrade the signal by adding noise and attenuation to it.

If you read the dCS marketing material, it quick jumps to listening tests which are of course not described.
 
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amirm

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Thread Starter #44
It is just hard to believe they all try to sell sneak oil to us.

Some other useful testing reference: https://www.soundonsound.com/techniques/does-your-studio-need-digital-master-clock
This has already been explained. If you have two DACs after just a few seconds or minute or two they will drift away from each other. A "44.1" kHz signal may actually be 44.101 KHz or 44.09 kHz. This won't make an audible difference but if you are trying to fade form one source to another in a live situation, the two will be out of sync. To solve this, you use a single clock that every DAC runs "slave" to it. That way, everyone marches to the same clock and stays in sync. This is a functionality thing and has nothing to do with fidelity.

This notion has been bastardized for home listening which has no use for syncing. Instead they are being sold as better clocks which is completely wrong.
 

lszomb

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#45
One more clarification:

"I test for this in my DAC reviews and with some rare exceptions, I can't find jitter that rises to the level of audibility."

Is this due to the input data are indeed jitter free? What is the normal jitter range introduced by CD transport, USB port, or BNC cable in different types of audio formats?
I knew there are some articles mentioned that those were hard to measure.

However, if we cannot measure how we can tell if we eliminated those successfully?

Thanks and Regards,



It is poor language. As I explained, in audio we don't care about absolute timing. If your song takes 362 seconds or 362.1 seconds, it will absolutely not make a difference. What makes a difference is if each audio sample is output at a slightly faster or slow time and keep changing (jitter). I test for this in my DAC reviews and with some rare exceptions, I can't find jitter that rises to the level of audibility. The fix for this is better implementation of the DAC and its local clock, not some external clock.

As a matter of pure engineering, there is no way to make an external clock as good as an internal one. The cable will degrade the signal by adding noise and attenuation to it.

If you read the dCS marketing material, it quick jumps to listening tests which are of course not described.
 

Mnyb

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#46
One more clarification:

"I test for this in my DAC reviews and with some rare exceptions, I can't find jitter that rises to the level of audibility."

Is this due to the input data are indeed jitter free? What is the normal jitter range introduced by CD transport, USB port, or BNC cable in different types of audio formats?
I knew there are some articles mentioned that those were hard to measure.

However, if we cannot measure how we can tell if we eliminated those successfully?

Thanks and Regards,

All properly designed DAC’s attenuate source jitter so good that it hardly make a difference anymore
 

Blumlein 88

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#48
One more clarification:

"I test for this in my DAC reviews and with some rare exceptions, I can't find jitter that rises to the level of audibility."

Is this due to the input data are indeed jitter free? What is the normal jitter range introduced by CD transport, USB port, or BNC cable in different types of audio formats?
I knew there are some articles mentioned that those were hard to measure.

However, if we cannot measure how we can tell if we eliminated those successfully?

Thanks and Regards,
Jitter in usb is of no consequence. It is transporting data which is buffered and asynchronous to the playback clock. The data is clocked out by the free running clock in the DAC which is the lowest jitter way to do it.

Various SPDIF or AES connections will have jitter, but usually nowhere near enough to be audible. It is one big overblown concern where there is no need for it.
 

miero

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#52
I think turned off the Master clock as suggested in the menu to compare the two modes and I was greeted with this:

View attachment 46694

The clock rate was all over the place as were the rest of the numbers. Clearly the DAC had lost its mind, I mean clock source. So much for any ability to compare. It took a reboot with its lengthy period to get functionality back. This is a serious bug as comparing the modes is exactly what you would want to do when you first get this clock.
IMO it is more probable that this is not a bug but a "feature" to support sales of external atomic clock!
 

Jimster480

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#53
This is so rediculous! They charge $9000 for a clock? There is no improvement that it could make for $9000 that would ever justify that price.
There are full units that cost less than 1/3 the price of the clock that beat both of these devices in performance...
 

Jimster480

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#55
"LEO GX is a breakthrough in digital audio system clocking — the first master clock ever that can feed a DAC directly with a working signal so precise we had to use new benchmarks to measure its performance. "
Yes, they had to make up new benchmarks because real benchmarks showed no improvements ;)
 
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amirm

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Thread Starter #56
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#57
I am just shocked that they would charge double the price of the DAC for the clock. They have gone to a school of economics I have not heard of....
Such economics actually make sense for luxury stuff
https://en.m.wikipedia.org/wiki/Veblen_good

However such consumption pattern seems to be dying out with more focus on yourself (yoga, travel, fancy food, experiences) rather than buying and storing stuff, however that depends on country and age
 
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#60
If you are wondering why distributed databases use atomic clocks you can read this Research paper.
what kinf of atomic clock do they put it inside? Rubidium? That could explain the price. I think they are also used for the GPS system.



ntp synchronization between data centers which are phisically complicated is difficult to get accuratly. Some at least use atomic clocks to get the time right (like the gps system).
Things are difficult in complex data centers. That's why key network archtects get paid what they do.
If you are wondering why distributed databases use atomic clocks you can read this Research paper.
what kinf of atomic clock do they put it inside? Rubidium? That could explain the price. I think they are also used for the GPS system.



ntp synchronization between data centers which are phisically complicated is difficult to get accuratly. Some at least use atomic clocks to get the time right (like the gps system).
Do you mean to say geographically dispersed data centers? You kind of missed the point. Even if atomic clock is local - client stations will not use icmp to synchronize. Ping by defination is used for other purposes not time. That was the minor correction , not to go on tangent on data center design- That's for a different forum . This is audio forum Let's close it -:).
 
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