I think Chris' comments above are most relevant.
As far as I know there is no cooling fan fitted.
My general experience with product design has been that if the packaging and shielding has been designed correctly EMI is less likely to be a problem, and measured performance if anything would improve.
As far as I know there is no cooling fan fitted.
My general experience with product design has been that if the packaging and shielding has been designed correctly EMI is less likely to be a problem, and measured performance if anything would improve.
Measuring jitter of the crystal source is a nice to have. Measuring the impact of the jitter on the source side is pretty straightforward and more important. A Jtest type signal (FS/4) to a high res FFT and look for sidebands. I doubt any of significance would show up. For the ADC jitter shows as an increased noise floor.
Either ADC or DAC measurements so far would have shown a problem and would have been addressed already.
Hi JensH,
Anything new regarding using AK4497?
It would be great to replace AK4490 with AK4497 if the THD and noise can be further improved.
@PaulBC
I haven't had much time to look at the AK4497 lately. According to the data sheet it should be an improvement over the AK4490. The dynamic range is definitely higher. I still need to verify the distortion.
@Philipp23
I normally use audioTester, but I have also used Arta and Steps for some measurements, which audioTester cannot do.
I haven't had much time to look at the AK4497 lately. According to the data sheet it should be an improvement over the AK4490. The dynamic range is definitely higher. I still need to verify the distortion.
@Philipp23
I normally use audioTester, but I have also used Arta and Steps for some measurements, which audioTester cannot do.
I'll wait for the software end 'till the equipment shows up. You never know what platform will be considered the least of a PITA to work with either.
Just upgraded Fedora 24 (buggy on that computer) to 25 workstation. So far, huge improvement. Maybe it just didn't like the hardware (although the Lenovo machines have been some of the best I've used).
-Chris
Just upgraded Fedora 24 (buggy on that computer) to 25 workstation. So far, huge improvement. Maybe it just didn't like the hardware (although the Lenovo machines have been some of the best I've used).
-Chris
Chris no need to wait; the software end will not work differently than it works with whatever is your current sound card. So you can start training right now
Jan
Unless these measurements were performed by loopback with the same device ... as then ADC and DAC are commonly clocked.
I agree that having a common clock may blur the picture.
I just made a couple of measurements, using two analyzers, one as generator and one as analyzer.
I measured the FFT with signals at 1 kHz and 12 kHz. I did not use a JTEST signal. I am not quite sure whether the JTEST signal makes sense in this case, since there is no clock regeneration.
The noise spikes at the high end of the frequency spectrum are generated by the DAC. They change depending on the input frequency and the level, but I don't think they are related to jitter. They are most likely a product of the delta-sigma process.
I just made a couple of measurements, using two analyzers, one as generator and one as analyzer.
I measured the FFT with signals at 1 kHz and 12 kHz. I did not use a JTEST signal. I am not quite sure whether the JTEST signal makes sense in this case, since there is no clock regeneration.
The noise spikes at the high end of the frequency spectrum are generated by the DAC. They change depending on the input frequency and the level, but I don't think they are related to jitter. They are most likely a product of the delta-sigma process.
Attachments
Hi Jan,
Yes, but this way my mind is on the job in one go.
My computer was just hit with a nasty trojan and it looks like I lost everything. I'd rather wait until the audio analyser is ready, who knows what computer I'll be using then. I'll probably dedicate a machine to the bench equipment anyway.
-Chris
Yes, but this way my mind is on the job in one go.
My computer was just hit with a nasty trojan and it looks like I lost everything. I'd rather wait until the audio analyser is ready, who knows what computer I'll be using then. I'll probably dedicate a machine to the bench equipment anyway.
-Chris
A dedicated PC is a good idea. Especially as it does not need to be a super fast/large memory unit. Audio and measurement tasks don't even stress an ancient '486 - remember those ;-)
My 1.2GHz Core2Duo Windows 7 notebook (6 years old, with 6GB RAM) doesn't seem to be fast enough when running 128k bin size FFT with 32bit/192kHz samples