Measurements and Review of Schiit Yggdrasil DAC

[Deleted member 65]

However the measurements done by Atomicbob over at Superbestaudiofriends (yes, I know, not great friends with audiosciencereview it seems ) paints a different picture on the measured performance.

Both measurements align, interpretations differ.

 

[Dimitrov]

Both measurements align, interpretations differ.

If that's the case when why are they up in arms over it? If it's just mere interpretation you would think their reactions would be different, but the guys over there are going a bit bonkers over the results as if to say that Amirs measurements were either outright wrong or fudged.

 

[Don Hills]

It's simply the bellowing of sacred oxen being gored.

 

[DonH56]

Anyway I’m a horse but don’t no one go thinking about taking me for a ride, it won’t go well for you

Hmmm... I used to ride some pretty gnarly horses, but only had to stay on for 8 seconds. Of course, I have read audio memory is only about 6 seconds, so maybe that's enough?

What's this thread about again? Does anyone care anymore?

 

[tili]

it’s about psychology

 

[rebbiputzmaker]

Hmmm... I used to ride some pretty gnarly horses, but only had to stay on for 8 seconds. Of course, I have read audio memory is only about 6 seconds, so maybe that's enough?

What's this thread about again? Does anyone care anymore?

DAC measurements.

 

[amirm]

However the measurements done by Atomicbob over at Superbestaudiofriends (yes, I know, not great friends with audiosciencereview it seems ) paints a different picture on the measured performance.

No, I don't post over there.

Now I'm not sure whose measurements are more accurate/reliable as I don't have any frame of reference and I don't have any experience in that field. It would be good to know either way!

I think the problem here is that hardly anyone has actually looked at atomicbomb's measurements. They are a sea of graphs, thrown out there with no comparison to any other products and darn difficult to sift through. If one focuses though, you can find similarities in his measurements and mind. Here is an example for example: jitter. I took his busy screen snapshot and annotated the main graph. First let's look at my measurement and then his:

Notice that I plot the full audible range and a bit more at the upper end to 22 kHz. Let's look at his:

Immediately we see the same jitter components hugging each side of our test tone. He is testing 44.1 kHz and mine is 48 Khz so the tone frequency is a bit different but same problem remains.

The distance between our main tone and the two sidebands is the jitter frequency. They are pretty close to the main tone which indicate they are pretty low frequencies and most likely mains/power supply related. Unfortunately his measurement only goes down to 7.5 kHz, making it impossible to confirm that. Look at my graph however and you see the problem right away with that yellow arrow.

This problem is very common in DACs so I don't see why he would not measure it, or investigate the cause of those low frequency jitters.

To a small extent, he also cuts off high frequencies after 14.5 kHz. Why? If anything the higher the jitter frequencies, the more audible they are (due to lack of perceptual masking).

Paul Miller's jitter suite used to do this and stereophile would publish them the same way but that was due to limitations in his gear. We have no such limitation in our modern equipment so the only reason to ignore low and high frequencies is to not want to see potential problems!

Also, as I explain in my audio measurement tutorial the software for our audio analyzers let's select the "FFT size." This is a software parameter that is adjustable. The larger the FFT size, the lower the measured noise floor. Of course nothing actually changes the noise floor of a DAC. We use this tool as to dig deeper in the noise floor for distortion spikes. Unfortunately he does not document the FFT size for his jitter measurements so there is no way to compensate for that difference. Seeing how his noise floor is lower than mine, he likely used a larger FFT.

Summary
The data is not as inconsistent as they are positioning them. By posting tons and tons of graphs and no per-measurement insight and comparison, they make it impossible to make sense out of what is there. People just zoom in on his summary line that Schiit products are excellent and wonder why the difference between his views and mine. As you all know, I put every graph in context, only post the bare minimum to capture everyone's eyes and explain what is there, what should be there, etc. While differences do exist in the measurements, the commonality is lost in all the back and forth. That common theme does indicate problems in this class product/price range.

 

[Rene]

I think the problem here is that hardly anyone has actually looked at atomicbomb's measurements. They are a sea of graphs, thrown out there with no comparison to any other products and darn difficult to sift through. If one focuses though, you can find similarities in his measurements and mind. Here is an example for example: jitter. I took his busy screen snapshot and annotated the main graph. First let's look at my measurement and then his:

Notice that I plot the full audible range and a bit more at the upper end to 22 kHz. Let's look at his:

View attachment 10848

Immediately we see the same jitter components hugging each side of our test tone. He is testing 44.1 kHz and mine is 48 Khz so the tone frequency is a bit different but same problem remains.

The distance between our main tone and the two sidebands is the jitter frequency. They are pretty close to the main tone which indicate they are pretty low frequencies and most likely mains/power supply related. Unfortunately his measurement only goes down to 7.5 kHz, making it impossible to confirm that. Look at my graph however and you see the problem right away with that yellow arrow.

This problem is very common in DACs so I don't see why he would not measure it, or investigate the cause of those low frequency jitters.

To a small extent, he also cuts off high frequencies after 14.5 kHz. Why? If anything the higher the jitter frequencies, the more audible they are (due to lack of perceptual masking).

Paul Miller's jitter suite used to do this and stereophile would publish them the same way but that was due to limitations in his gear. We have no such limitation in our modern equipment so the only reason to ignore low and high frequencies is to not want to see potential problems!

Also, as I explain in my audio measurement tutorial the software for our audio analyzers let's select the "FFT size." This is a software parameter that is adjustable. The larger the FFT size, the lower the measured noise floor. Of course nothing actually changes the noise floor of a DAC. We use this tool as to dig deeper in the noise floor for distortion spikes. Unfortunately he does not document the FFT size for his jitter measurements so there is no way to compensate for that difference. Seeing how his noise floor is lower than mine, he likely used a larger FFT.

Summary
The data is not as inconsistent as they are positioning them. By posting tons and tons of graphs and no per-measurement insight and comparison, they make it impossible to make sense out of what is there. People just zoom in on his summary line that Schiit products are excellent and wonder why the difference between his views and mine. As you all know, I put every graph in context, only post the bare minimum to capture everyone's eyes and explain what is there, what should be there, etc. While differences do exist in the measurements, the commonality is lost in all the back and forth. That common theme does indicate problems in this class product/price range.

Amir, the difference I see between the jitter measurements is that your file shows spurs at about 250Hz and Bob's at what looks like 60Hz and 120Hz. I wonder if these are production variations. Did you see any difference between the two Yggis you tested at Max's?

 

[garbulky]

Can low frequency spurs actually cause jitter in the resulting dac signal?

 

[amirm]

Amir, the difference I see between the jitter measurements is that your file shows spurs at about 250Hz and Bob's at what looks like 60Hz and 120Hz.

I have those too. Here is the zoomed version I post in the initial review:

I didn't put a market at 60 Hz but it is also there in addition to 120 and 240.

 

[amirm]

Can low frequency spurs actually cause jitter in the resulting dac signal?

Of course. The power to the clock circuit is modulated by mains frequencies and that shows up in the output of the DAC. It can also bleed into the reference voltage for the DAC.

 

[Jimster480]

Hi there. I was asking more about the technical performance than outright sound quality because the latter is far more controversial and subject to personal opinion, but if it measures better in almost every department it would be reasonable to suspect it would either :

1) Sound better
or ...
2) Sound the same, because the measured differences are still far below audible thresholds

I have no opinions on the Yggdrasil as far as sound quality goes, but I'm curious about the poor (relative) measured performance compared to far less expensive products. However the measurements done by Atomicbob over at Superbestaudiofriends (yes, I know, not great friends with audiosciencereview it seems ) paints a different picture on the measured performance.

No, I don't post over there.

Now I'm not sure whose measurements are more accurate/reliable as I don't have any frame of reference and I don't have any experience in that field. It would be good to know either way!

If there are inexpensive DACs that can rival or outperform far more expensive options then I'm all for it and IMO, the public should be made aware of it.

BTW, when I say outperform, I'm referring to the technical measured performance. If someone like me can spend $200-300 and achieve performance on par/"better" than a product costing $2000 then why not?

IMHO it would be hard for me to trust anything posted at SBAF because they are a chest-beating Schiit fanboy site. If you read through a few of their threads you will find the average member is extremely immature and they basically bash anyone who isn't buying schiit products or suggests that there is a better product outside of a schiit product.
When you find people like that, you realize that they are heavily bias and whatever they say should be taken with a grain of salt from that point on.

I was originally looking to sign up on that site as another place to talk about audio related topics, but after I checked out a few threads I really wasn't interested in being a member.

And if you read the thread about "amirgate" you will see just how disgusting they can be which further makes them lose credibility.

 

[garbulky]

Of course. The power to the clock circuit is modulated by mains frequencies and that shows up in the output of the DAC. It can also bleed into the reference voltage for the DAC.

If I'm reading you correctly, these low frequency spurs you showed on the graph cause some sort of jitter/aberration to be produced of which impact can be measured in some way on the rca or xlr analog outputs of a typical dac? I.e. it would change the analog output signal from what it should be?

 

[amirm]

If I'm reading you correctly, these low frequency spurs you showed on the graph cause some sort of jitter/aberration to be produced of which impact can be measured in some way on the rca or xlr analog outputs of a typical dac? I.e. it would change the analog output signal from what it should be?

That is exactly what I am measuring! The analog output of the DAC.

Some people measure the clock that drives the DAC but that requires opening the unit and at any rate, shows faulty information because not all of the contributions from the clock get to the output of the DAC.

 

[garbulky]

That is exactly what I am measuring! The analog output of the DAC.

Some people measure the clock that drives the DAC but that requires opening the unit and at any rate, shows faulty information because not all of the contributions from the clock get to the output of the DAC.

Ah okay, I didn't understand that. Thanks for calrifying. So in this case whatever signal you fed it somehow produces an addition -90db signal at the bottom end due to jitter issues? I didn't realize that jitter could create a new signal. I thought it was about timing.

 

[amirm]

Correct. Jitter changes the timing in time domain. The graphs show that in frequency domain. There, we get symmetrical sidebands on each side of our tone proportional to the frequency of jitter.

 

[amirm]

BTW, it is quite excellent that you figured that out by yourself! It is a complex topic and without intuition.

 

[garbulky]

Correct. Jitter changes the timing in time domain. The graphs show that in frequency domain. There, we get symmetrical sidebands on each side of our tone proportional to the frequency of jitter.

I guess that's where I'm getting confused with the low -90 db spur. That's a real tone right at -90 db? Much higher than the two smaller spurs. And it's at a totally different frequency. So it's not just timing, it's creating new tones somehow?

 

[amirm]

Do you mean the extreme spike on the left side? If so, that tends to be an anomaly of measurements (creating DC signal).

 

[March Audio]

I guess that's where I'm getting confused with the low -90 db spur. That's a real tone right at -90 db? Much higher than the two smaller spurs. And it's at a totally different frequency. So it's not just timing, it's creating new tones somehow?

There are many sources of spurious signals that can appear in a dac output.

Jitter - This is a variation in the timing of the clock signal that the dac chip uses. In simple terms If the clock speeds up and slows down this directly changes the frequency of the signal the dac is producing. So if we play a fixed tone, such as the 12kHz in Amirs plots, you can see the frequency of the variation as discrete signals either side of the fundamental tone. The clock signal can also be affected by more random like noise and this appears as skirts at the bottom of the signal. AS Amir said the clock signal can get polluted by many sources including mains 50 or 60 Hz. You will usually see harmonic multiples of these frequencies, 100,150hz and 120, 180Hz. You often see this at those frequencies and as sidebands either side subtracted and added to the fundamental tone you are measuring.
Also the source of the clock has an impact. Asynch usb uses a clock signal generated by a component in the dac close to the dac chip. This minimises problems. Spdif and aes carry the clock from the source and it is extracted by the receiving dac using a circuit called a phase locked loop. Variations in the source and limitations of the PLL can allow jitter components to appear. Also data patterns can creaate jitter. Whilst many dacs are extremely good at extracting the clock from spdif/aes, some are not. USB avoids these issues.

Harmonic distortion - Non linearity in the dac chip or the following output amplifier can cause muliples of the fundamental frequency to appear, 2,3,4,5 x etc.

Intermodulation distortion - related to harmonic distortion, again if non linear, where there are two different tones they will create further tones at frequencies of the two signals added and subtracted from each other. Several types of test show this, you will typically see 19 and 20kHz tones producing a 1kHz tone and 60Hz and 7kHz tones producing modulated sidebands of 60Hz around the 7 kHz tone.

Of course mains pick up is insidious and you can see 50 and 60 Hz plus harmonics on some dac outputs.

Other spurious signals can include idle tones produced in the dac chip and tones picked up from the general digital noise in the dac. Amir had already mentioned poor dac reference voltages and noise.

So really we are looking for anything that shouldnt be there, the above is a very general guide to the most obvious

I will add some pictures to this post later to help clarify.