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Auralic LEO GX DAC Clock Review

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Audio clocks as far as I've seen in a friend's studio may make sense when you want to use a dedicated dac with and a instrument interface (such as M-audio) to synchronise its digital outputs (Toslink or Coaxial SPDIF usually) with the dac, thus bypassing the analog outs. It doesn't have to be external, the dac could implement it too. My friend's M-audio interface had clock sync BNC coaxial connectors to sync with an Adat as another comment said above but I guess you can use an external source aswell such as the Auralic or dcS. In multithousand dollar studios you may hear the improved sound.
 

digicidal

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Whoever your source for the y2k wasn't a big issue, ignore them from now on, it's BS. It was a big issue, but lots of people fixed it before it happened, it's a classic case of people dismissing something they didn't understand.
Yup... I remember working 80+ hour weeks for several months prior. In hindsight I should have demanded a "grossly overpaid consultant" be hired instead. Dealing with patches, replacements, certifications, etc. was a total nightmare.

Of course, at the time I was working for a large industrial laundry company... and the amount of hardware and software controls designed in the 70s and 80s that was still in active production was ridiculous. Nice thing was that at least (for once) we didn't have to lobby the CFO for every single purchase - although that only changed when the news was finally on top of the situation. The prior years of trying to update/upgrade anything was always met with a firm "meh" from the bean counters. :mad:
 

jackenhack

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Well, if you want to go crazy, just get a used rubidium atomic clock or GPSDO from eBay for a pittance. Connect it to my frequency generator card, where you can get eight different frequencies at 0 PPM and replace all your oscillators in your DAC. It won't sound better, but it will be insanely exact. And total cost will be a coupe of hundred dollars.

https://www.jackenhack.com/si5351c-i2c-frequency-clock-generator-breakout-board/
 

PenguinMusic

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Hi guys,

If I read most of the comments here, a lot of fun is made of the Auralic Clock becasue it sells an "Atomic Clock" for 8000$ and that clock does make no audible difference ?

Where is the threshold for audible difference ?

Because I am a little new here, but I am under the impression that the differences for most of the DAC tested on this site lately are all beyond audible difference, assuming they're decently designed.

Of course, I may be wrong as I am a perfect noob...

Please do NOT GET ME WRONG : I am not saying that this thing is worth buying (I can't agreee more on the fact it is not except if you have 8000$ that you really want to throw away for just a nice looking box...).
 
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Hi amirm,
Thanks for your insight in this clock option. I am surprised you couldn't measure nor hear the difference.
Looking at you spectrum analysis showed a very clean performance even without the clock option.

For those who are skeptic, the idea of an external clock makes a lot of sense in a few applications:

The first is when you have a disk player and a DAC. If these devices are connected via spdif, toshlink or AES/EBU it is almost impossible to get a really low clock jitter. These connections are flawed in getting the data and clock across. Even the best PLL will always show some residue of data induced jitter.
20 years ago I was involved in a connection called i2s.e, developed by Ultra Analog for Sonic Frontiers. It was system that transported clock and data over separate wires inside a multi coax cable. This connection always sounded better than any other.
So if you clock the DAC and clock the transport from the same clock you can remove this problem. This could be done by using a nice clock in the DAC and slave the transport or slave both to an external clock (= more expensive, and not necessarily better unless the internal clock is poor)

The second application (which I think Auralic tried to solve here) is when you have a streaming DAC that can also lock to a transport. This kind of DAC uses 2 VCXO crystal oscillators. One for the 44.1kHz family and up, and one for the 48kHz family and up.
They are VCXO's (voltage controlled x-tal oscillator) because the incoming clock from a transport can be relatively off. So a circuit measures the difference between the incoming clock and the VCXO clock and adjusts the latter with a PLL to lock to the incoming clock and it wil try by using a low frequency filter to clock with as little jitter as possible.
This is a good method, and better than most VCO's which are a lot cheaper but less accurate. (the X is missing from X-tal) The original digital audio input chip from Crystal Semiconductor, the CS8412 and CS8414 were such solutions. They were used in virtually all DACs 20 years ago and didn't do a good job with respect to jitter.

But now this same DAC is used as a streaming DAC. This is an asynchronous method. The DAC is master and the data from the streaming engine (USB or Ethernet) is asynchronously put into a small buffer and filled in the rate the DAC is eating the data.
Now the VCXO of the DAC is not in a locking mode, but in a free running mode. Often they just supply half the supply voltage to the VCXO control pin to put it in this stable middle control position.
But the fact that the VCXO can be controlled makes it less precise. Noise on the control pin will result in jitter of the clock. Now the use of VCXO is not the best method, but a fixed X-tal would be, but will cost extra.

So feeding it with a clean external clock could be beneficial. Using a rubidium (atomic) clock is BS, as it doesn't say anything about the jitter. It only makes sure that the track is finished at exact the run-time and not plays 20ms longer or shorter.
The trick of the external clock is that it should have an extreme low jitter and the absolute frequency if it is within a few ppm doesn't really influence the sound.

Your test proves to me that the Auralic DAC (in standalone not locked mode) has a very clean clock. The external Leo wil most likely only make the absolute time more precise but didn't improve on jitter.
The fact that the unit locked up when you removed the clock proves to me that their VCXO was in a bad controlled state until you rebooted.

Just my 5 cents in this discussion.
 
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vkvedam

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LOL...

Totally understand your feeling even though I never really liked the NAIM sound...
But I would be the same if they did it with Linn :) or with SimAudio/Moon.

Cheers.
Linn was measured before, it did measure decently
 
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LOL...

Totally understand your feeling even though I never really liked the NAIM sound...
But I would be the same if they did it with Linn :) or with SimAudio/Moon.

Cheers.
have not tried linn or simaudio
However Naim with my Dynaudios is pretty awesome ...like they’re made for each other
 

Costas EAR

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I played through a few of my reference files and I was shocked to hear a bit more detail. There was more air between instruments. The bass was ever so slightly quicker. I don't think I have ever heard a DAC sound this good before!

Of course, none of that happened. The DAC sounded just as good as it did yesterday without the external clock. I did not try to time the tracks to see if they finish more on time so maybe they did.
I dropped coffee on myself.:p
 

Soniclife

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please no Naim lol

I’m in love with the sound and don’t want to see behind the curtain!
Just remember measurements don't change how something sounds. There is nothing wrong with liking the sound of an effects box, and the hobby would be better off if people just admitted that to themselves.
 

jsrtheta

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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.
I read a comment on Archimago's site where a guy had his signal run through TEN daisy-chained clocks, which he swore made an audible improvement. I couldn't bring myself to respond.
 

PenguinMusic

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Just remember measurements don't change how something sounds. There is nothing wrong with liking the sound of an effects box, and the hobby would be better off if people just admitted that to themselves.
Hi,

Perfectly agree...

Measures allow to give an objective description to a subjective feeling.
I think that the purpose of measures should be to explain why I like one thing and why I don't like the other.
I think that measures should not tell me what to like or not.

But from experience, you need to have at least 2000 posts to make that kind of statement without being flamed for that in here :-(
So of course, I don't think anything of the above statement I made until my next 1870 posts :)

Regards.
 

PenguinMusic

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Linn was measured before, it did measure decently
Hi,

Good to know :)
As I really love the "Linn sound" (if I am allowed to speak that way).

I could never afford an Lin pre-amp, but everything that is behing pre-amp used to be Linn.

Basically :
- Oppo BDP105 used as pre-amp => feeding 2 X Linn 5125 with active cards => feeding 2 Linn Keltiks (front) and 1 Linn 5120 (center).

I had other Linn amps to power the Linn Kaber used as rear speakers.
But they got defective.
No money to replace that.
So I took 3 SMSL SA98e...
Not efficient enough to drive the Kaber, but for rear speakers, I'll call it enough :-(

Regards.
 
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Dear all,
I am far to be a specialist, so I do not understand how this could work with the SPDIF input of the DAC... How can the external clock act as a master clock if it is not connected to the source (PC or streamer)?
Sorry if my ignorance made me missed something...
Dominique
 
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