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On 1/29/2021 at 8:21 AM, SwissBear said:

Hi everyone,

 

We had an interesting discussion the other day with @Miska on the subject of 10 MHz clocks. I was trying to make the point that 10 MHz clocks had an interest in music reproduction which  Jussi refuted, explaining that the conversion of 10 MHz signal to frequencies usable by DAC oscillators (multiples of 44.1 kHz and 48 kHz) added jitter and was therefore not useful.

 

At the end of the discussion, Jussi shared some measurements of his Holo Spring 2 DAC, which were in fact not comparable to the ones I had published, essentially because he was measuring multiples of 44.1 kHz to show how powerful his technology of HQPlayer was in reducing jitter, when increasing sampling frequency to PCM 1.4 MHz or DSD 256. Measurement published by Jussi and mine were not comparable because the upsampling drastically reduces jitter, at least on his DAC and also because we had no idea of the number of samples used to make the FFT in either measurements, which has a direct impact on the noise floor.

 

To come back to my point, and to the comparison of things which are comparable, here is a graph of the jitter measured at the output of an R2R DAC, in connection with an interface SU-2. 

 

Please note that you cannot compare the noise floor with Jussi's measurement as we do not know how many samples were used to produce this FFT. Also, the impulse is at 12 kHz as the sampling frequency is 48 kHz. Please also note that the x-axis has been very much enlarged.

 

In red, measurement of the jitter induced by the oscillators of the SU-2 (Accusilicon AS-318B).

In blue, measurement of the jitter when the SU-2 is connected to an external 10 MHz clock which is cold.

In green, measurement of the jitter when the SU-2 is connected to an external 10 MHz clock which is hot (after 12 hours of warming).

 

20210129102254.thumb.png.d1dd7cc20f127249a8b073d0c5d50a8e.png

 

I am tempted to infer from this graph that Yes, definitely, 10 MHz clock can have a beneficial influence on the J-test measurements of jitter, made at a DAC. I am also tempted to infer that Singxer has a good knowledge on how to implement these technologies.

 

Hope this helps :-)

 

Reference: http://www.erji.net/forum.php?mod=viewthread&tid=2216213&page=1#pid33553664

 

[EDIT] Measurements have been made by l7audiolab.com (https://hv6mkka65l5nbcgw64taospppe--www-l7audiolab-com.translate.goog/f/tmmt再出发/). The 10 MHz clock was Gustard C-18. 


This is a very helpful post. 

Text beneath is from here

Quote

SDA-6 supports external clock input, among which USB supports 10M clock input, and other interfaces support WCK input. In USB mode, it also supports 50 and 75-ohm switchable input impedance.


I’m considering upgrading my Modified SU-1 with an SU-2 which also has 10 MHz clock input. 
Since external OCXO clocks has such an positive impact on the EtherRegen, I would expect same on a USB to SPDIF Converter. 
 

I would expect the USB and clock interface and circuits is shared between the SDA-6 and SU-2.

SU-6 isn’t an option for me, as lack of external 10 MHz clock. 
Denafrips could be an option, but also lacking 10 MHz clock input.

 

So far I haven’t found any converters that’s offering 10 MHz clock input. 
 

EDIT:

(I forgot posting almost same in this tread). Thanks again for great answers. 

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  • 2 weeks later...

Got an SU-2. Not connected yet. Just on power. Should equal burn in. 
One guy told me an USB to SPDIF converter can’t use or benefit from an external 10Mhz clock. 
 

Makes me wonder where this external clock is used in the SU-2. 

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6 hours ago, R1200CL said:

Got an SU-2. Not connected yet. Just on power. Should equal burn in. 
One guy told me an USB to SPDIF converter can’t use or benefit from an external 10Mhz clock. 
 

Makes me wonder where this external clock is used in the SU-2. 

 

The goal of the SU-2 is to convert an USB flow, which is asynchronous, into SPDIF or I2S, both of which are synchronous music flows, which embark music data together with a clock signal. So connecting a high precision clock to the SU-2 will allow the output flow to be clocked by this high precision clock.

In case your DAC follows the clock signal included in the SPDIF or I2S flow, you will benefit from this high precision clock signal.

This is the case of the SDA-6 which is mentioned here.

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13 hours ago, SwissBear said:

 

The goal of the SU-2 is to convert an USB flow, which is asynchronous, into SPDIF or I2S, both of which are synchronous music flows, which embark music data together with a clock signal. So connecting a high precision clock to the SU-2 will allow the output flow to be clocked by this high precision clock.

In case your DAC follows the clock signal included in the SPDIF or I2S flow, you will benefit from this high precision clock signal.

This is the case of the SDA-6 which is mentioned here.

 

My limited understanding on the subject of clocks for digital audio is that you don't need a high precision clock. 

 

Some explanations are provided here in response to the measurements you also posted on ASR: 

 

https://www.audio “science” review/forum/index.php?threads/singxer-sda-6-influence-of-a-10-mhz-clock.19922/

 

There are also some who claim that the precision of the clock is not the issue, but all the RF going on inside the DAC (especially when inputting high bandwidth signals as USB, I2S, SPDIF...).

 

You can understand there could be some skepticism about all this, (and the cost of a REF-10 at 4000€ is significant).  This begs one question: have others done this aside from you or are you just relating your own "in house" experimentation ? Did anyone actually listen to your setup (SDA6 with and without the REF-10) aside from you ?

my blog

 

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33 minutes ago, hopkins said:

Some explanations are provided here in response to the measurements you also posted on ASR: 

 

https://www.audio “science” review/forum/index.php?threads/singxer-sda-6-influence-of-a-10-mhz-clock.19922/

 

There are also some who claim that the precision of the clock is not the issue, but all the RF going on inside the DAC (especially when inputting high bandwidth signals as USB, I2S, SPDIF...).

 

You can understand there could be some skepticism about all this, (and the cost of a REF-10 at 4000€ is significant).  This begs one question: have others done this aside from you or are you just relating your own "in house" experimentation ? Did anyone actually listen to your setup (SDA6 with and without the REF-10) aside from you ?

 

Skepticism is welcome. The reactions on the other forum you mentioned was not skepticism, but dogmatism IMO.

 

There are some high level DAC manufacturers who believe that high precision clocks are part of the game of rebuilding a decent analog signal from digital audio. Here are some examples:

https://www.dcsltd.co.uk/products/rossini-clock/

https://www.ch-precision.com/product/t1-10mhz-time-reference/

 

My intention in this thread is to show that there is no need to go for such expensive solutions and that one can find cheaper alternative in case on is sensitive to such benefits.

 

As already explained about Diretta and its benefits, not everyone is sensitive to the effets of precise clocking.

You might not be interested or skeptic. This does not make the subject irrelevant for others.

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Thanks for all this, but you did not answer my question (and I did not say this was uninteresting!).

 

BTW I also think timing is key, the question is how to achieve it...and how to make sure percieved changes are consistent, shared by others, and isolated (cannot be attributed to other factors). 

my blog

 

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14 hours ago, SwissBear said:

In case your DAC follows the clock signal included in the SPDIF or I2S flow, you will benefit from this high precision clock signal.

Can’t say how my old Theta Generation VIII deal with AES/EBU. I taught it could only be one way ?

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7 hours ago, R1200CL said:

Can’t say how my old Theta Generation VIII deal with AES/EBU. I taught it could only be one way ?


if you already own the SU-2, you are not far from getting the answer though. You can just find an AES/EBU cable and listen for yourself.

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Yes, of cause. I probably didn’t understand your first answer. 

Quote

In case your DAC follows the clock signal included in the SPDIF or I2S flow

 

As there are DAC’s that don’t benefit from the clock signal included in the SPDIF. 

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2 hours ago, R1200CL said:

Yes, of cause. I probably didn’t understand your first answer. 

 

As there are DAC’s that don’t benefit from the clock signal included in the SPDIF. 

 

I'm not sure. What I noticed with my experience with I2S is that the inability of some DACs to not use their PLL was making the use of an external clock less productive. But with AES/EBU, PLL seems to be necessary as we need to correct for the jitter introduced by the cable if I'm correct.

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Sorry if this has been already covered but I would like to know if Singxer SDA -6 has a built-in volume control and can be used directly with an active speaker such as mine?
And is it good enough to be used in this way or would I need a preamp, as I don't like to have an extra component in my system. I prefer to go DAC direct to amp.
Thanks.

Audirvana+3.0 / Qobuz Studio / Mac Mini (256GB SSD - 16GB RAM)

Lindemann Musicbook: 20 DSD, ATC EL 150ASL

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14 minutes ago, mevdinc said:

Sorry if this has been already covered but I would like to know if Singxer SDA -6 has a built-in volume control and can be used directly with an active speaker such as mine?
And is it good enough to be used in this way or would I need a preamp, as I don't like to have an extra component in my system. I prefer to go DAC direct to amp.
Thanks.

 

SDA-6 does not have a volume button. You can adjust the volume using HQPlayer as I am doing. Alternatively, you can use a small preamp. Singxer has one which is quite cheap and good. SA-1 if I'm not mistaken. See here: https://translate.google.com/translate?sl=zh-CN&tl=en&u=https://www.l7audiolab.com/f/measurements-of-singxer-sa-1-headphone-amppre-retail/

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8 hours ago, SwissBear said:

I'm not sure. What I noticed with my experience with I2S is that the inability of some DACs to not use their PLL was making the use of an external clock less productive. But with AES/EBU, PLL seems to be necessary as we need to correct for the jitter introduced by the cable if I'm correct.

 

You need a PLL when you need to recover an external clock into usable local clock. IOW, when you are a clock slave. Like in case of S/PDIF or AES/EBU (or I2S for that matter although implementations vary).

 

When you have a local clock oscillator, you don't need a PLL. IOW, when you own the master clock. Like in case you are using USB or network interface like NAA.

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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5 hours ago, SwissBear said:

 

SDA-6 does not have a volume button. You can adjust the volume using HQPlayer as I am doing. Alternatively, you can use a small preamp. Singxer has one which is quite cheap and good. SA-1 if I'm not mistaken. See here: https://translate.google.com/translate?sl=zh-CN&tl=en&u=https://www.l7audiolab.com/f/measurements-of-singxer-sa-1-headphone-amppre-retail/

That's a shame.
I have used software volume control before and it's got even better recently, but not sure if it's as good as analog volume. I was hoping Leedh processing would be the ultimate digital volume solution but it doesn't seem to have taken off.
I guess I could give software volume control another try but it's scary to send 100% volume to my active speakers accidentally.

Audirvana+3.0 / Qobuz Studio / Mac Mini (256GB SSD - 16GB RAM)

Lindemann Musicbook: 20 DSD, ATC EL 150ASL

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2 hours ago, Miska said:

 

You need a PLL when you need to recover an external clock into usable local clock. IOW, when you are a clock slave. Like in case of S/PDIF or AES/EBU (or I2S for that matter although implementations vary).

 

When you have a local clock oscillator, you don't need a PLL. IOW, when you own the master clock. Like in case you are using USB or network interface like NAA.

 


So in other words, the theory is that a converter like the SU-2 will benefit from a good clock ?

Clocks matters and play a role in USB to SPDIF conversion ?

 

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1 hour ago, R1200CL said:


So in other words, the theory is that a converter like the SU-2 will benefit from a good clock ?

Clocks matters and play a role in USB to SPDIF conversion ?

 

 

No one really has the answer to that last question! In theory a clock with 1ps precision is more than enough. In practice... 

 

USB transmits the data and provides information on the sample rate. The The data goes into a buffer at the reciever end, and it is during the conversion to spdif that the clock signal is generated. 

 

Whether a high precision clock will really translate into lower jitter during  the USB/Spdif converter is debateable. 

 

There is not much point in going into technical debates as no one here (including myself) is sufficiently competent to know what is really going on. If you ask DAC manufacturers you will also get different points of view. 

 

You can try and trust your years, as SwissBear seems to have done. 

 

My personal experience is that noise reduction in the usb/spdif converter, without any change in clocks, has a very significant impact on timing accuracy, as the clocking seems adversly affected by RF. But noise (RF) reduction in a converter is not something we can "improve" ourselves by tweaking, or at least not significantly. 

 

My 2 cents. Best to try for yourself :) 

 

my blog

 

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3 minutes ago, Miska said:

 

But why would you use something like SU-2 with SDA-6?

 

I never understood such setups. To me it is analogous to this:

- You buy a Ferrari, but you want another engine on it, so you buy a Lamborghini and connect to the two with a towing rope. And then tow the Ferrari around with the Lamborghini. And then the combination is somehow better than the Ferrari alone...

 

 

Yes, if you have a better clock at the source (USB to S/PDIF converter), then the PLL at receiver side has better chances or recovering a clean clock from the S/PDIF signal. But where do you need such converter these days where it would matter? Most of the time you can go with straight USB and skip the S/PDIF part. Of course someone may have an old DAC that doesn't have USB input or such.

 

 

You'll still need a clock at some point... 

my blog

 

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5 minutes ago, hopkins said:

You'll still need a clock at some point... 

 

Good oscillator either inside the USB-to-S/PDIF converter (if you really need to use such).

 

Or preferably inside the DAC, sitting right next to the actual D/A conversion stage. This is the normal case these days when using USB.

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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Just now, Miska said:

 

Good oscillator either inside the USB-to-S/PDIF converter (if you really need to use such).

 

Or preferably inside the DAC, sitting right next to the actual D/A conversion stage. This is the normal case these days.

 

 

Yes. You avoid jitter in the transmission. But you can also get maximum noise injection from USB into the DAC. Which is why some people like Toslink, for example. There's no ideal situation... 

my blog

 

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2 minutes ago, hopkins said:

Yes. You avoid jitter in the transmission. But you can also get maximum noise injection from USB into the DAC. Which is why some people like Toslink, for example. There's no ideal situation... 

 

But none of this requires any external 10 MHz clocks (which by definition has wrong frequency anyway).

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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1 hour ago, Miska said:

But why would you use something like SU-2 with SDA-6?

 


Maybe I should start a SU-2 tread. 
 

I don’t have a SDA-6. My idea is to upgrade my SU-1. I’m totally dependent on a converter after the opticalRendu. 
 

I’m just trying to understand if the Idea with an better clock was somewhat meaningless. As I have been told that a converter don’t use a 10 MHz clock.

 

The diagram is under developed. It won’t be clocking this way. 

 

 

E62A243D-8555-4D79-9F77-4340EEA3075F.jpeg

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1 hour ago, Miska said:

Of course someone may have an old DAC that doesn't have USB input or such.

Exactly 😀

Theta Generation VIII S3

And it’s still a very good DAC. 

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