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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz

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#9,422
#9,425
soekris said:
As stated maybe a million times before before, the dam1021 have the Si514.
Click to expand...

Sorry, I missed the million times.

But I didn't miss the million times you stated the SI570 is a very high performance part, even used in Rockna ad MSB DAC.

And now after you've praised the performance of the si570 countless times I find that you use the SI514, the 5 EUR lower grade version (RMS Phase Jitter 0.8 ps 12 kHz to 20 MHz integration bandwidth!).

I'm a little confused, now I have difficult to follow your reasoning
 
#9,426
andrea_mori said:
Sorry, I missed the million times.

But I didn't miss the million times you stated the SI570 is a very high performance part, even used in Rockna ad MSB DAC.

And now after you've praised the performance of the si570 countless times I find that you use the SI514, the 5 EUR lower grade version (RMS Phase Jitter 0.8 ps 12 kHz to 20 MHz integration bandwidth!).

I'm a little confused, now I have difficult to follow your reasoning
Click to expand...

The Si514 was selected for the dam101 at first because it meet the performance requirements, was reasonable priced, and had low power consumption to not stress the linear 3.3V power supply.... You know, engineers have to balanced things....

Most of my later dams and dacs use the Si570. For your experiements, maybe the dam1121-1 would be a better choice.... It use the Si570 and the clock don't go though the FPGA.
 
#9,428
soekris said:
The Si514 was selected for the dam101 at first because it meet the performance requirements, was reasonable priced, and had low power consumption to not stress the linear 3.3V power supply.... You know, engineers have to balanced things....

Most of my later dams and dacs use the Si570. For your experiements, maybe the dam1121-1 would be a better choice.... It use the Si570 and the clock don't go though the FPGA.
Click to expand...

It doesn't really matter much since as soon as I have measured the phase noise I will replace the front end.

Only you've always praised the SI570 so I thought you used it on all your devices.

However as you know I would have never used any of the Silabs VCXO so not much difference.
Maybe jitter < 1 ps in audio application is not appropriated since the 12 kHz to 20 MHz integration bandwidth used for the measurement is not suitable for mobile applications either.
 
#9,429
"CONCLUSION

In order to determine the maximum acceptable size of jitter on music signals, detection thresholds for artificial random jitter were measured in a 2 alternative forced choice procedure. Audio professionals and semi-professio-nals participated in the experiments. They were allowed touse their own listening environments and their favoritesound materials. The results indicate that the threshold for random jitter on program materials is several hundreds ns for well-trained listeners under their preferable listening conditions. The threshold values seem to be sufficiently larger than the jitter actually observed in various consumer products"

Whats wrong here?

(PDF) Detection threshold for distortions due to jitter on digital audio

//
 
#9,432
TNT said:
"CONCLUSION

In order to determine the maximum acceptable size of jitter on music signals, detection thresholds for artificial random jitter were measured in a 2 alternative forced choice procedure. Audio professionals and semi-professio-nals participated in the experiments. They were allowed touse their own listening environments and their favoritesound materials. The results indicate that the threshold for random jitter on program materials is several hundreds ns for well-trained listeners under their preferable listening conditions. The threshold values seem to be sufficiently larger than the jitter actually observed in various consumer products"

Whats wrong here?

(PDF) Detection threshold for distortions due to jitter on digital audio

//
Click to expand...

Seven hypotheses from my side:
1. The level of jitter of the playback system was not regarded. The laptop may have had large jitter from itself, masking the added jitter. Depending also on the jitter suppression in the DACs itself.
2. The jitter was simulated. It may be that not all artifacts caused by jittery sources were properly simulated.
3. The level of jitter in the source material was not regarded.
4. The listening setup was not documented. Was this done with headphones or speaker systems? What was the quality of reproduction?
5. The source material was not documented. Was very high quality recorded material used? Were sufficient high frequencies present?
6. What kind of DACs were used? R2R, DS? What sample rates?
7. The investigation was targeted for distortion. I do not think that this is the most severe problem caused by jitter. I'd think frequency modulation would be more audible than amplitude problems. Also, factors like stereo image and long-term listening comfort should be considered...
 
#9,433
TNT said:
"CONCLUSION

In order to determine the maximum acceptable size of jitter on music signals, detection thresholds for artificial random jitter were measured in a 2 alternative forced choice procedure. Audio professionals and semi-professio-nals participated in the experiments. They were allowed touse their own listening environments and their favoritesound materials. The results indicate that the threshold for random jitter on program materials is several hundreds ns for well-trained listeners under their preferable listening conditions. The threshold values seem to be sufficiently larger than the jitter actually observed in various consumer products"

Whats wrong here?

(PDF) Detection threshold for distortions due to jitter on digital audio

//
Click to expand...

I don't know if there is something wrong.

My empirical experience is much different, and even the experience of those who have improved the master clock replacing the oscillators with better ones.

Of course, everyone is free to stay with the Silabs VCXO and to live happy with it.
I respect different opinions but I keep mine.
 
#9,434
analog_sa said:
It is rather simple. The distinction helps create an interesting pricing structure with the 1121. Few buyers will be persuaded by the higher precision resistors, but throw in a better clock and the 02 becomes the obvious underdog.

Have you never sold anything?
Click to expand...

No sorry, we are hobbyist not audio professionals with business interests.

Our target is the best as possible regardless of the cost, just the spirit of audio diy.
 
#9,435
fedde said:
Seven hypotheses from my side:
1. The level of jitter of the playback system was not regarded. The laptop may have had large jitter from itself, masking the added jitter. Depending also on the jitter suppression in the DACs itself.
2. The jitter was simulated. It may be that not all artifacts caused by jittery sources were properly simulated.
3. The level of jitter in the source material was not regarded.
4. The listening setup was not documented. Was this done with headphones or speaker systems? What was the quality of reproduction?
5. The source material was not documented. Was very high quality recorded material used? Were sufficient high frequencies present?
6. What kind of DACs were used? R2R, DS? What sample rates?
7. The investigation was targeted for distortion. I do not think that this is the most severe problem caused by jitter. I'd think frequency modulation would be more audible than amplitude problems. Also, factors like stereo image and long-term listening comfort should be considered...
Click to expand...

I subscribe all of your points and I would add for those who have not yet experienced:

try yourself the comparison so you can draw your own conclusions.
 
#9,436
chris719 said:
Indeed, it is. There is no data, nothing, nada showing that close-in phase noise is an audible problem, nevermind at -80 dBc @ 10 Hz offset.

Please don’t take this as an invitation to debate further in Soren’s thread. I have no interest anyway. You have your own thread to discuss solutions to imagined problems. I do admire your work, I just don’t think it’s nice to beat people up over reasonable design decisions in their own thread.
Click to expand...

Hear, hear!
 
#9,437
Indeed, although I have all the rights to comment around the design choices because I'm a customer and we are on a diy audio forum, since many users don't like my posts I have opened a dedicated thread.

But if you think I don't even have the right to open my own thread you can ask the moderators for closing the thread.
 
#9,438
@Andrea,

Of course you're entitled to your opinion, however that doesn't include posting claims about products without providing factual data to back up those claims, as then it quickly becomes slander, and slanderous posts are just something we don't want or need.

If I were you I'd provide irrefutable measurement data for your claims as then the discussion becomes technical, and unlike opinions, technical discussions are based on facts and thus can be checked and verified.
 
#9,439
Just for a little distraction, and of course to console my own curiosity (which is of a far, far lower level [emoji18]):
I‘ve been lurking around quite some time now, and have visited soekris site, too, and still am a little overwhelmed...
Are the DACs from the oem-line available to the diy-community, and would it be reasonable to build a single one 1921? Or are there too many constraints—for a unextperienced builder that I am?
 
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