[Researcher]

Very helpful post. Yea, like the Xspdif2 was measured so well by ASR but its own of the worst ddc for me. I even powered it with hdplex + lps1.2

Neither did Xspdif measure well, nor it was recommended at ASR.

 

[kumar402]

Neither did Xspdif measure well, nor it was recommended at ASR.

Well if you really wanna quote ASR then you shouldn’t venture into DDC and just use USB from laptop my friend and be done with. Here is something for you from ASR
Finally, please note that we are seriously "measurebating here." I have to zoom in so much into performance of these signals that breathing on them may change things. So do not worry about any audibility issues here. Use USB if that comes with your DAC and be done with it. Don't string all these things together thinking you are doing something useful.

 

[JaMo]

ASR is not relevant or even near a role model representative for any objective or near truth HiFi performance writings. They are a community with their own, not necessarily a primarily a HiFi, agenda. Often they shoot down good techniques and praises cheap ones. Some times I wonder if they are in music listening at all... ?! Or just to miscredit the competition.. for earning money..

Choose for Yourself

 

[Flm09]

Wow! Adding U18 DDC makes things more analog sounding. Don't notice a blacker background though! This is just usb to DDC and coax out to Draco. Haven't tried I2S yet!

 

[Researcher]

Guyz please get slow! I know u had already invested in it.

Someone here claimed Xspdif is well measured on ASR. I just highlighted the truth.

 

[Crypt Keeper]

...

 

[Crypt Keeper]

Guyz please get slow! I know u had already invested in it.

Someone here claimed Xspdif is well measured on ASR. I just highlighted the truth.

You should try U 18 with good clock, nice PW cable and SR Purple fuse... My unit is also connected to power regenerator and for $ 450 it's just awesome ...

 

[kumar402]

Guyz please get slow! I know u had already invested in it.

Someone here claimed Xspdif is well measured on ASR. I just highlighted the truth.

It’s just a $450 device and not an “investment “ for anyone. Ppl here pay $450 for cable for chi-fi headphone. No one is defending it because we have “invested” in it but because it genuinely works well and if some ps jitter makes difference to whatever DAC you own then get something with less ps jitter.
Ppl in head-fi have invested in far worse and expensive items and have called out their shortcomings as and when needed. There are some long time member here who don’t think like I have “ invested” on it so let’s praise it.

 

[801evan]

Nothing is consistent with what is measured and real life usage. External psu is better than usb power on the Xspdif2 but measurement say otherwise. Topping d10 sounds better than the Xspdif2 but is noisier. While the d20 isn't perfect as it has some edge in the sound, it is blacker and less hazy.

Hard to trust this u18 measurement as it's the usual negging and that Wildism products are better than others. Just search for "su6" here and most people say the u18 is better and that's more credible.

 

[T 1000]

I do not dispute the importance of measurements, but it is obvious that measurements cannot be an indicator of how something sounds.
This is shown in the example of U18, it measures worse but sounds better.
Recently, a well-known reviewer provided evidence based on measurements that cables (all) do not make any difference in sound, of course, all supported by graphical representations of different measurements.
I believe that engineers, when listening to what they have designed, resort to adjustments (better measurements are not always better) in order to achieve a better final hearing result.
Of course this is just my guess

 

[MartinWT]

The two 'investments' that have been long standing in my system are my Usher speakers (now 14 years old) and my Belles power amp.

All other equipment stays around for as long as it's best within my buying power. The Sonore UltraRendu, Gustard X26 Pro and (newest) Gustard U18 show every sign of being long-term 'keepers'. That doesn't mean they'll last forever, but it's always the music that comes first.

 

[soumya.banerjee]

@GoldenOne
J-Test on APX can be tricky. I recall stereophile's J-Test measurements for Sonnet Morpheus being less than ideal and was called out by Cees
https://www.stereophile.com/content/sonnet-morpheus-da-processor-manufacturers-comment

I didn't expect this much deviation from Gustard's own published measurements. Assuming the unit you evaluated wasn't bad, can you tally your J-Test parameters with Gustard's depicted here in this pic.

 

[kumar402]

@GoldenOne
J-Test on APX can be tricky. I recall stereophile's J-Test measurements for Sonnet Morpheus being less than ideal and was called out by Cees
https://www.stereophile.com/content/sonnet-morpheus-da-processor-manufacturers-comment

I didn't expect this much deviation from Gustard's own published measurements. Assuming the unit you evaluated wasn't bad, can you tally your J-Test parameters with Gustard's depicted here in this pic.

So as per Cees, if any digital product has “steep digital filter” then these J-test are ok but for product that doesn’t have “Steep Digital filter “ the results are not true indicative of real life jitter. Now I took 2 example
1 . Gustard U18 - this uses below for signal processing
CLPO for signal processing, the isolated IIS signal is reshaped to remove the jitter introduced by the isolator.
2. Singxer SU-6 - “FPGA-based source synchronization technology re-shaping the isolated I2S signal”

Does it mean SU-6 may be using steep digital filter and U18 not and hence J-test may not be correct for U18? Can someone with technical know how help me understand?

 

[soumya.banerjee]

So as per Cees, if any digital product has “steep digital filter” then these J-test are ok but for product that doesn’t have “Steep Digital filter “ the results are not true indicative of real life jitter. Now I took 2 example
1 . Gustard U18 - this uses below for signal processing
CLPO for signal processing, the isolated IIS signal is reshaped to remove the jitter introduced by the isolator.
2. Singxer SU-6 - “FPGA-based source synchronization technology re-shaping the isolated I2S signal”

Does it mean SU-6 may be using steep digital filter and U18 not and hence J-test may not be correct for U18? Can someone with technical know how help me understand?

Generally we talk of filters in context of ADCs (anti-aliasing) or DACs (re-construction) which is what Cees was pointing out.
That said, APx itself has band-pass or notch filters and different windowing + averaging parameters. I am merely curious if any of these affect J-Test drastically.

Also it will be interesting to see if there is a difference in J-Test measurements when measured via a DAC fed by by the DDC.
Again, this is all purely academic ; time-domain measurements are very very tricky and never as straight forward as frequency domain measurements.
That said, I really like how U-18 sounds - more so with higher sampling rates / up-sampling via IIS.

I don't know if Gustard engage here at head-fi, but it makes sense to check with them to determine the disparity between the published and GoldenOne's measurements.

 

[GoldenSound]

J-Test on APX can be tricky. I recall stereophile's J-Test measurements for Sonnet Morpheus being less than ideal and was called out by Cees
https://www.stereophile.com/content/sonnet-morpheus-da-processor-manufacturers-comment

Sonnet's comment about the J-Test here is completely valid, and you can see it demonstrated on other DACs. The J-Test requires a steep filter to be valid, and so doing it on a NOS dac for example will seem to show very poor jitter even if that isn't the case.

On the Rockna wavedream as an example from a different manufacturer:

J-Test in NOS/'Filter Off':

But with steep filter ('Linear'):

However this is for a J-Test, which is not the test I did on the U18 (or other DDCs).
The J-Test is used to test jitter at the analog output of a DAC, but with a DDC you can simply measure the jitter directly on the digital connection's clock signal itself, which is what my DDC measurements show. And this is not susceptible to the same issue as it is not dependent on reconstruction at all.

I didn't expect this much deviation from Gustard's own published measurements. Assuming the unit you evaluated wasn't bad, can you tally your J-Test parameters with Gustard's depicted here in this pic.

There's a few odd things about Gustard's own published measurements.

1) Not really sure why they're posting a THD+N test. This is a digital device, it's either bitperfect or not. Harmonic distortion could be added in DSP but assuming a DDC is bit-perfect a THD+N test is irrelevant. (The U18 is bit perfect, I've not encountered any DDC which wasn't so far other than the Chord MScaler which is of course intended to alter/upsample audio passed through it)

2) If I use exactly the same settings as they've chosen and play real music through the device (note that they do not show what waveform they were playing), I get the following:

Very very similar so there doesn't seem to be any discrepancy.
The RMS Jitter value though has no context for settings so I can't repeat it.

But, in the full screenshot they do show, there are a couple things to note about how they've configured things:

- They have their filters configured to the 'audible range' between 50hz and 22khz, which is not really what you should be looking at for jitter.
Jitter does not create a 1:1 result, ie: jitter at 1khz does not mean that you'll have unwanted noise at 1khz on the output, it means you'll have unwanted content 1khz either side of the fundamental frequency. So if you were playing a 15khz tone and your source had a lot of 1khz jitter, you'd have unwanted content at 14khz and 16khz.
For this reason, you cannot consider jitter in terms of a straight 'audible range'.
The AES3 standard specifies a corner frequency at 700hz and the APx555 defaults to a High-Pass 700hz and Low-Pass 100khz which is what I personally use for my measurements.
AP has a pretty thorough document on jitter as a subject which may be interesting to some: http://www.audiophilleo.com/zh_hk/docs/Dunn-AP-tn23.pdf

- They are running the U18 at 192khz. This is fine, as some music is going to be at 192khz, but it is not representative of MOST music, and performance at 44.1khz and 192khz is going to be different. Additionally 48khz base rates typically perform better than 44.1khz base rates due to it being easier to clock divide between the 48mhz USB rate and 48khz sample rate than it is to go from 48mhz to 44.1khz.
This occurs on many DACs and DDCs, and is why I include J-Tests for both rates on DACs and jitter tests at both rates for DDCs.
In any case, you cannot compare 192khz performance to redbook performance.

Repeating the above test but at 44.1khz looks like this: