The craziest DAC ever #9038AP with distortions analyzer onboard.

[digititus]

@IVX шикарный проект!

 

[ZeDestructor]

Or master clock in/out to keep multiple boards in sync despite having separate USB connections - just stack up as many as you need for your channel count.

Do the individual DACs go out of sync more than a few cycles worth anyways?

 

[scott wurcer]

How about a self-calibrating DAC?

Where is the reference "perfect" sin wave here to calibrate against.

 

[gvl]

Where is the reference "perfect" sin wave here to calibrate against.

If there's DSP to run FFT it can conceivably also generate the sine and feed it to the DAC? With some hw changes of course.

 

[scott wurcer]

If there's DSP to run FFT it can conceivably also generate the sine and feed it to the DAC? With some hw changes of course.

That sin wave (analog out) is then only as good as the DAC. The AP generates a precision analog sine wave as stimulus that sets the limit of what can be measured. If you want to calibrate a voltmeter you need a standard voltage to put into it that is as good or better than the resolution of the voltmeter.

 

[gvl]

That sin wave (analog out) is then only as good as the DAC. The AP generates a precision analog sine wave as stimulus that sets the limit of what can be measured. If you want to calibrate a voltmeter you need a standard voltage to put into it that is as good or better than the resolution of the voltmeter.

I do have some grasp of metrology, although it is a couple of decades in the past now... It's a DAC, so having a sine wave that is as good as the DAC is a reasonable goal? Perhaps I misunderstood the product, but the way I read it you can monitor the FFT of the output of the DAC in real time and tweak the ESS THD compensation registers at the same time. You could generate a "perfect" digital sine wave, feed it to the DAC, and automatically adjust the THD compensation for the lowest harmonics values all using onboard hardware/firmware is what I meant by self-calibration. What am I missing?

 

[scott wurcer]

Perhaps I misunderstood the product, but the way I read it you can monitor the FFT of the output of the DAC in real time and tweak the ESS THD compensation registers at the same time. You could generate a "perfect" digital sine wave, feed it to the DAC, and automatically adjust the THD compensation for the lowest harmonics values all using onboard hardware/firmware is what I meant by self-calibration. What am I missing?

I'm just having trouble with the wording of the OP, I assume it's not just a DAC but includes an analyzer and needs some processing power.

 

[gvl]

I'm just having trouble with the wording of the OP, I assume it's not just a DAC but includes an analyzer and needs some processing power.

That's how I read it.

 

[carlosmante]

Where is the reference "perfect" sin wave here to calibrate against.

"Where is the reference "perfect" sin wave here to calibrate against"?
There is not " perfect" in Metrology.

 

[gvl]

"Perfect" is a term.

 

[flowjm]

An inexpensive high performance DAC with volume control and DSP/room correction would sell very, very well in my opinion, and I'm honestly surprised that there are basically no such products available.

 

[gvl]

Yup, being able to set PEQ by reading REW-produced filters file would be nice.

 

[Max]

An inexpensive high performance DAC with volume control and DSP/room correction would sell very, very well in my opinion, and I'm honestly surprised that there are basically no such products available.

Totally agree. This market is important and the existing solutions are either very expensive or limited (like minidsp tied to Dirac)

 

[gvl]

REW/PEQ/Convolution on PC is free, but if you need to room correct your CD player then I agree a simple inexpensive solution is missing.

 

[somebodyelse]

Do the individual DACs go out of sync more than a few cycles worth anyways?

I guess that's down to the tolerances on your individual DAC clocks, and how long you leave it running before doing something that effectively resyncs them. The alsa docs do explicitly mention it though.

 

[IVX]

gvl, "perfect" sine-wave in the digital domain isn't a big deal, right? DSP does that within its resolution 24/96, I see no difference DSP digital sine vs AP digital sine, 9038 has exactly the same THD. And you are right, you can tweak 2nd and 3rd harmonic compensation, and see the resulting harmonics online. In fact 9038AP is DAC+HPA+"AP-like analyzer at single frequency 1kHz". In the same way, as you can adjust THD of ES9038 at standard 1kHz, if you have a real AP analyzer, you can do the same with my 150x50mm board without AP analyzer.

 

[gvl]

gvl, "perfect" sine-wave in the digital domain isn't a big deal, right? DSP does that within its resolution 24/96, I see no difference DSP digital sine vs AP digital sine, 9038 has exactly the same THD. And you are right, you can tweak 2nd and 3rd harmonic compensation, and see the resulting harmonics online. In fact 9038AP is DAC+HPA+"AP-like analyzer at single frequency 1kHz". In the same way, as you can adjust THD of ES9038 at standard 1kHz, if you have a real AP analyzer, you can do the same with my 150x50mm board without AP analyzer.

Sounds like I understood the product correctly. So the onboard DSP is already sending 1kHz to the DAC chip? Must be.

 

[JohnYang1997]

How you deal with thermal drift? And how many frequency points does it work at?

 

[IVX]

gvl, sure the only way to measure the THD in that case I believe.

 

[IVX]

JohnYang1997, why I should care about your thermal environment? You may perform distortions measurement any time you wish, cold either hot whatever, next save the preset with 2nd/3rd harmonics correction and name it "calibration at +35C" or "calibration at -10C"