Jitter blocking

[Guido Tent]

A crystal is always high Q.

Strictly spoken, the environment of the crystal also defines Q

best

Guido

 

[Lucifix]

   Hello,
 this is my test board which I made last year. It uses SRC4392 as S/PDIF receiver and jitter cleaner, the Master Clocks being provided by the on-board PLL1708. I know that it needs some customization to improve sound quality at its outputs this is why I would be happy if you could give me some advice or share your impressions with me.

 Best regards,
  Lucifix

 

[rossl]

Actually, looking at the jitter attenuation specs:

the CS8416 rolls off at about 20dB/decade above 12KHz with a 2dB peak in the passband.

the LMK03000 rolls off at about 40dB/decade above 6KHz with a butterworth response.

Does this make a difference? I've no idea. Is it better? Certainly seems so but are there any disadvantages like slow lock time?

Well you've peaked my interest enough to look at the price

$13 is OK, but the LLP package isn't very DIY friendly.

The loop filter may be able to be weaked to be acceptable for audio. However, the part needs a micro to load it's registers at power on. That make it more expensive.

The jitter spec is worse for clock recovery mode that it is for clock distribution mode.

The Wolfson SPDIF receiver can just power up in hardware mode.

And, like you point out, I can solder the Wolfson part myself but would need to go to an assembler with a reflow machine to correctly solder down the LLP part.

For all the trouble, I'm not sure it will be any better than the WM8804.

 

[rossl]

Dustin

I find it difficult to understand how your ASRC can be ready for production 18 months ago and now it's gone no further. Now you have a DAC which seems to be going along teh same route.

Isn't it time you brought home the bacon?

Gopher

I don't know if Dustin is still following this thread, but this information is available to the public on the web:

http://blog.stereophile.com/ces2008/011008ess/

http://www.esstech.com/techsupp/sabrewp.pdf

 

[Iain McNeill]

In my mind, it seems like jitter will manifest itself in the audio as frequency modulation. If the jitter spectrum is noise (I assume this is the case) then the jitter will cause random frequency modulations of the audio signal.

Would I be correct in assuming that as the jitter worsens, the frequency deviation of the modulation components (sidebands) gets greater while the amplitude stays the same?

Psychoacoustically, the actual audio signal will then mask the jitter components until it gets bad enough. But then what will it sound like? A harshness perhaps? These jitter components won't be harmonically related.

Has anyone done any work on this before I go and make my head hurt with the math? I guess what I'm interested in knowing is a) what does jitter sound like and b) at what point does jitter become audible.

 

[abzug]

Hi Dan,


Well the ASRC project hasn't gone much further as a standalone part. The DAC however is done and is being sampled now to customers. The basic idea is that it is a 8 channel DAC capable of 128dB DNR and 120dB THD+N in 8 channel mode. It can aslo be run in 2 channel mode with 132 dB DNR and 120dB THD+N. Now im going to work on an audio ADC which should be fun. Anyways, im not sure where the marketing group is in what they call the "rollout" but I do know there should be some news of the part being made public soon. If there is a particular project or product you have in mind for this DAC, let me know and ill see if I can get you some engineering samples if you like.


THanks

CLD

Is this it? http://blog.stereophile.com/ces2008/ess.jpg

I made a new thread before I realized the connection: http://www.diyaudio.com/forums/showthread.php?s=&threadid=117026

 

[Guido Tent]

In my mind, it seems like jitter will manifest itself in the audio as frequency modulation. If the jitter spectrum is noise (I assume this is the case) then the jitter will cause random frequency modulations of the audio signal.

Would I be correct in assuming that as the jitter worsens, the frequency deviation of the modulation components (sidebands) gets greater while the amplitude stays the same?

Psychoacoustically, the actual audio signal will then mask the jitter components until it gets bad enough. But then what will it sound like? A harshness perhaps? These jitter components won't be harmonically related.

Has anyone done any work on this before I go and make my head hurt with the math? I guess what I'm interested in knowing is a) what does jitter sound like and b) at what point does jitter become audible.

soundwise jitter manifests itself in various areas:

- harsh sound, makes me want to reduce the volume, or worse, switch off completely
- "stress" in music, impossible to listen to it in a relaxed manner
- reduced definition of small signals
- soundstage and focus. Focus is not as sharp as possible, soundstage less clear
- ambiental reproduction, the sense of being there is reduced, if present at all

best

Guido

 

[dusfor99]

Hi Gopher,


In responce to the following


"Dustin

I find it difficult to understand how your ASRC can be ready for production 18 months ago and now it's gone no further. Now you have a DAC which seems to be going along teh same route.

Isn't it time you brought home the bacon?

Gopher "

The DAC didn't fall into the same abyss that the ASRC did and is now available. Thanks RossL for puting the links. I haven't been following DIY closely because I was dissapointed about the path the ASRC went and I really dont have many samples to give to people, so I lost interest. Now that the DAC is out and avaible, I will follow this more closely


Thanks


CLD