Measurements of an ES9023 DAC

[ghg]

Originally Posted by fitzfish

Hi HP,
The R&S HPV analizer I have has some limitations.
I cannot do greater than 256K points and averaging in the FFT window is not implemented.
Dave

Well, looking at the UPV manual, it states "AVG count" in the FFT section,
give it a try.

BR

Gary

[HpW]

Dave,

Originally Posted by fitzfish

Hi HP,
What were you looking to see in this picture?

Dave

there are some symmetric waves: +/- ... 5Hz, 12Hz, 22Hz, 50Hz in the -120.. -130dB region.

We have also to consider the FFT size (256K), while as used in my measurement (2^25) this will lower the bin distance and the noise level / bin, but in the other hand clear modulated (symmetric around the carrier) will be visible.

Hp

[fitzfish]

Hi Gary,

Originally Posted by ghg

Well, looking at the UPV manual, it states "AVG count" in the FFT section,
give it a try.

That function setting (average, expo0nential, flat...) works for the calculation measured parameter calculation (THD for example) in the firmware on the UPV I have, but does not affect the FFT monitor screen available. The post FFT function is not implemented in this firmware release, which I assume is where it would be...

I'm working on a really old firmware version with the UPV I have. Version 1.4. Updates to the current version 3.2 are possible but I have to step through one or two previous versions to get to the latest. I had been waiting to do so until I sent it in for an upgrade to add the digital interface incase there was an issue upgrading and it went down.

Originally Posted by HpW

there are some symmetric waves: +/- ... 5Hz, 12Hz, 22Hz, 50Hz in the -120.. -130dB region.


We have also to consider the FFT size (256K), while as used in my measurement (2^25) this will lower the bin distance and the noise level / bin, but in the other hand clear modulated (symmetric around the carrier) will be visible.

I can see how the higher FFT point size and/or averaging is desirable. Each FFT screen update when zoomed at this level changes. There are no repeatable peaks as are obvious in the other captures I took. I will make the attempt to update the firmware to see if the added enhancements also include FFT features that will help with this measure.

Thanks,
Dave

[fitzfish]

Hi Hp, Gary,

Originally Posted by HpW

Dave,

there are some symmetric waves: +/- ... 5Hz, 12Hz, 22Hz, 50Hz in the -120.. -130dB region.

We have also to consider the FFT size (256K), while as used in my measurement (2^25) this will lower the bin distance and the noise level / bin, but in the other hand clear modulated (symmetric around the carrier) will be visible.

Hp

Firmware update successful - Updated picture of the 44.1/16 Jtest signal with 256K points, averaging 10 measurements per and zoomed in to +/- 100Hz. The 9023 looks to have good data correlated jitter rejection in our implementation ... Still limited FFT point size with the tool I have either way.

Dave

[sgrossklass]

Looks like very, very low jitter levels that nobody needs to worry about.

Your THD and IMD measurements may be limited by the analyzer, at least assuming the DAC sticks to its -94 dB THD spec and the output stage doesn't mess that up. 2nd and 3rd at -90 dB each would be entry-level soundcard level (e.g. Xonar DG) at best.

It may be interesting to run the usual intersample-over tests, though I doubt the designers of a modern-day DAC digital filter would mess up there.

[HpW]

Originally Posted by fitzfish

Hi Hp, Gary,

Firmware update successful - Updated picture of the 44.1/16 Jtest signal with 256K points, averaging 10 measurements per and zoomed in to +/- 100Hz. The 9023 looks to have good data correlated jitter rejection in our implementation ... Still limited FFT point size with the tool I have either way.

Dave

Hmm, looks like as from a different DUT.

Hp

[fitzfish]

Hi Sgrossklass

Originally Posted by sgrossklass

Your THD and IMD measurements may be limited by the analyzer, at least assuming the DAC sticks to its -94 dB THD spec and the output stage doesn't mess that up.

The THD floor is ~120db for the instrument I have.

The 9023 does not perform to -94 dB FS (2V RMS) @ 1kHz as far as I can tell, even when pretty optimally implemented. THD improves as the frequency rises and gets a little worse lower. I can verify this by measuring in 80KHz or greater bandwidth. My guess is that THD performance is a function of power in the internal opamp, or perhaps from the charge pump.

The follower buffer/LPF performs in the mid ninety dB range as implemented.

Originally Posted by sgrossklass

2nd and 3rd at -90 dB each would be entry-level soundcard level (e.g. Xonar DG) at best.

Agreed, but this sounds like no sound card I have used and measures better in every other way I have tested. @Juli and EMU0404 are all I have had to compare it to. Neither comes close to the detail, silence, or placement of instruments in the image while listening here. This is not to say that there is not something better...


I'm happy to defend the design as a whole though for its simplicity and performance vs. cost. Looking at the music in my library on an oscilloscope I have not found tracks with sustained levels at 2V RMS, or even 1.5V. In the 0.5 to 1V range the 9023 works very well and has the noise floor, dynamic range, and jitter performance to make it shine where most music I listen to is.

Originally Posted by sgrossklass

It may be interesting to run the usual intersample-over tests, though I doubt the designers of a modern-day DAC digital filter would mess up there.

Is there a standardized testing method for this?

Thanks,
Dave

[fitzfish]

Hi Hp,

Originally Posted by HpW

Hmm, looks like as from a different DUT.

Hp

Nope, same one. I have two of these buit up identically and they both perform similarly. I am reasonably sure this is the same one used for the original testing as it has not left that bench and the other is in the system to listen to...

Here are the two measurements side by side again. Any peaks and troughs in the one on the left (no averaging) are random and move around with every sweep.

I did not get the grid set up the same as all of the presets went away with the upgrade. Apologies there.
Dave

[cersepn]

Any further updates on how the 9023 sounds? No news is usually good news

[EUVL]

No news can also mean very busy making a living.




Patrick