Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter - Page 216 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th January 2013, 02:53 AM   #2151
diyAudio Member
 
Join Date: Jan 2009
Send a message via MSN to Adrculda Send a message via Yahoo to Adrculda
AD9525 total overkill ???
__________________
Regards,
Adrian
  Reply With Quote
Old 19th January 2013, 07:51 AM   #2152
diyAudio Member
 
Join Date: Feb 2009
Location: Brisbane, Australia
Quote:
Originally Posted by iancanada View Post
I have a WaveIO USB. But Iím not happy with the 2.5ns jitter problem on I2S output caused by XMOS, though itís no longer an issue working with my FIFO.

That 2.5ns problem has got to make you wonder why TPA are spending a few years developing their own XMOS based design usb adapter
  Reply With Quote
Old 19th January 2013, 08:15 AM   #2153
TNT is offline TNT  Sweden
diyAudio Member
 
TNT's Avatar
 
Join Date: Apr 2003
Location: Sweden
Quote:
Originally Posted by Adrculda View Post
AD9525 total overkill ???
Some numbers are impressive but -89dbc/hz at 100hz is not the best we have seen.
Attached Images
File Type: png ad9.png (422.9 KB, 345 views)

Last edited by TNT; 19th January 2013 at 08:15 AM. Reason: 85->89
  Reply With Quote
Old 19th January 2013, 04:34 PM   #2154
diyAudio Member
 
Join Date: Jan 2009
Send a message via MSN to Adrculda Send a message via Yahoo to Adrculda
Quote:
Originally Posted by TNT View Post
Some numbers are impressive but -89dbc/hz at 100hz is not the best we have seen.
Yes I agree, but a lot better to hear the noise in the higher audio band where its will be more pronounced. I would rather have it where its nearly inaudible rather than in the 8K - 20K range....
__________________
Regards,
Adrian
  Reply With Quote
Old 19th January 2013, 04:40 PM   #2155
TNT is offline TNT  Sweden
diyAudio Member
 
TNT's Avatar
 
Join Date: Apr 2003
Location: Sweden
Adrian, noise in the clock manifest itself as distortion and not "noise" as in schhhsssss.
  Reply With Quote
Old 19th January 2013, 10:34 PM   #2156
diyAudio Member
 
Join Date: Apr 2010
Hi! Anybody did a listening test with the fifo between the SI530 and CCHD-957 oscillator modules ?? availability of 22.579mhz part is problematic...
  Reply With Quote
Old 20th January 2013, 05:47 AM   #2157
diyAudio Member
 
Join Date: Jul 2009
Ian

When I connected an optical source to the SPDIF, it has lock LED on but no sound at the BIII, both Mute and Lock LEDs on BIII on, the system works perfectly with WaveIO connected to the I2S backdoor. Please HELP.
  Reply With Quote
Old 20th January 2013, 08:40 AM   #2158
sp502 is offline sp502  Greece
diyAudio Member
 
Join Date: May 2006
Quote:
Originally Posted by hochopeper View Post
That 2.5ns problem has got to make you wonder why TPA are spending a few years developing their own XMOS based design usb adapter
I am curious to know why you and others are referring to the 2.5ns jitter of the XMOS chip (could be any other chip as well) as a "problem".
Do you believe that the proper and/or unique point for perfect timing accuracy should be at the chip that "translates" USB data to I2S signals?
Why to try to be perfect in timings close to the source? Should we go back to the synchronous USB transports as well?
If you use a very simple I2S re-clocking circuit, similar to the ones found here, don't you get excellent results?
(Of course there are some limits of the amount of jitter that can be compensated, but I believe 2.5ns is orders of magnitude lower).

I think that many times there are exaggerated comments about the performance of some components without the proper justification.
Many functions may be performed in various points of a telecommunication chain/system (and audio reproduction may be considered as one).
Fortunately the contemporary digital systems provide excellent mechanisms that assist the design of a system that has not to be perfectly synchronous from the one end to the other.

Ian's design proves that there are ways to connect two different clock domains and get perfect results, with the only constraint of the buffer size.
But if you use the same clock for both the USB to I2S conversion system and the DAC, one very simple re-clocking system is enough (no buffer is needed).
The DAC will get all the bits jitter-free and you can have the clock(s) and re-clocking mechanisms really close to the DAC where is more important.

"Problems" like this should be the boost for better circuit designs that may not be simpler, but may provide better results than the "simplistic" ones.
  Reply With Quote
Old 20th January 2013, 11:58 AM   #2159
diyAudio Member
 
andrea_mori's Avatar
 
Join Date: Jan 2005
Location: Italy
Quote:
Originally Posted by sp502 View Post
But if you use the same clock for both the USB to I2S conversion system and the DAC, one very simple re-clocking system is enough (no buffer is needed).
The DAC will get all the bits jitter-free and you can have the clock(s) and re-clocking mechanisms really close to the DAC where is more important.
..subscribed.. exactly what I said some posts ago.

The asynchronous way (the FIFO buffer) is the right option if you cannot synchronized the DAC with the source (USB to I2S conversion or any other source).
Anyway, IMHO, the DAC (BCLK) should be feeded directly from the MCLK, as close as possible to the DAC chip. also if you are using an asynchronous re-clock like the FIFO buffer.
  Reply With Quote
Old 20th January 2013, 01:40 PM   #2160
diyAudio Member
 
Join Date: Jul 2009
Quote:
Originally Posted by bigpandahk View Post
Ian

When I connected an optical source to the SPDIF, it has lock LED on but no sound at the BIII, both Mute and Lock LEDs on BIII on, the system works perfectly with WaveIO connected to the I2S backdoor. Please HELP.
Ian

Same problem on the coaxial input, so only the I2S backdoor is working.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
XMOS-based Asynchronous USB to I2S interface Lorien Digital Source 2112 Yesterday 11:53 AM
exaU2I - Multi-Channel Asynchronous USB to I2S Interface exa065 exaDevices 1357 3rd March 2014 08:51 PM
DAC chip selection + I2S jitter questions drwho9437 Digital Line Level 2 26th July 2010 12:50 PM
Simple FIFO to I2S CPLD, for MCU players / reclocking KOON3876 Digital Line Level 21 19th September 2008 04:00 PM
asynchronous reclocking and low jitter clocks ash_dac Digital Source 3 8th February 2005 09:22 AM


New To Site? Need Help?

All times are GMT. The time now is 04:39 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2