Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

The Well synchronized asynchronous FIFO buffer - Slaved I2S reclocker
The Well synchronized asynchronous FIFO buffer - Slaved I2S reclocker
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 28th August 2020, 01:19 PM   #71
andrea_mori is offline andrea_mori  Italy
diyAudio Member
 
andrea_mori's Avatar
 
Join Date: Jan 2005
Location: Italy
The FIFO Lite has to be tested and optimized, so I don't think it will be available in the new GB.

The FIFO Lite has 4 x I2S input so one can implement USB, S/PDIF and so on using external converter.

External boards operate in a different domain, the FIFO takes care to isolate them from the DAC.
  Reply With Quote
Old 13th September 2020, 04:06 PM   #72
andrea_mori is offline andrea_mori  Italy
diyAudio Member
 
andrea_mori's Avatar
 
Join Date: Jan 2005
Location: Italy
Default Raspberry PI as standalone source

Since we are planning to implement a Raspberry as a standalone source for our audio system, we have developed a few boards to interface it with our new FIFO.
The source includes the Raspberry PI, the 7" touch screen and an expansion boards to connect a SSD.
The SSD expansion board is stacked under the RPI.

The first board (TWSAFB-RPI) is an interface to the Raspberry and it's stacked onto the RPI. It provides power supply for the RPI and the Touch screen, and also a rail to supply the I2S transmitter. The I2S output is isolated from the Raspberry.

The second board (TWSAFB-TX) is the I2S LVDS transmitter powered by the TWSAFB-RPI.

The third board (TWSAFB-RX) is the I2S LVDS receiver to be placed far from the Raspberry and close to the FIFO. Its I2S output is isolated from the trasmitter to avoid any EMI/RFI interference. The input part of the receiver is powered by the transmitter, while the isolated output has to be powered by the FIFO.

An ordinary HDMI cable is used to connect the transmitter to the receiver.
Attached Images
File Type: jpg TWSAFB-RPI.jpg (153.4 KB, 312 views)
File Type: jpg TWSAFB-TX.JPG (165.7 KB, 311 views)
File Type: jpg TWSAFB-RX.JPG (193.4 KB, 307 views)
File Type: jpg TWSAFB-RX-TX.JPG (287.1 KB, 278 views)
  Reply With Quote
Old 14th September 2020, 06:31 PM   #73
Supersurfer is offline Supersurfer  Netherlands
diyAudio Member
 
Join Date: Feb 2013
That looks promising Andrea!

I am wondering; why do you want to use the raspberry pi while the usbridge signature from Allo is a better solution regarding the noisyness of the rasperry pi ps components on the boards.
  Reply With Quote
Old 14th September 2020, 09:24 PM   #74
andrea_mori is offline andrea_mori  Italy
diyAudio Member
 
andrea_mori's Avatar
 
Join Date: Jan 2005
Location: Italy
I wouldn't use the PC as the source so the USB is not practicable.

The Raspberry is a simple and cheap device to be used as a standalone source.

The problem is that the Raspberry generates a lot of EMI/RFI, so some precautions are mandatory (switch off BT and WiFi, keep the RPI far from the digital chain and so on).

Finally, if the FIFO does correctly its job nothing can pass from the source to the DAC. Otherwise, if the FIFO is source dependent IMHO there is somwthing wrong.

I see many members who struggle tweaking the Raspberry, using ultra low noise regulators to supply it or even removing the on board regulators.
But as I said several times IMHO the problem is not the RPI, the real problem is the FIFO that does not isolate the DAC from the source, that's the reason why we have choosen a totally different architecture.
  Reply With Quote
Old 14th September 2020, 09:51 PM   #75
tubo is offline tubo  Philippines
diyAudio Member
 
Join Date: Apr 2007
Location: Chicago
This is very exciting andrea. I’d buy your devices once available
  Reply With Quote
Old 15th September 2020, 05:55 PM   #76
Supersurfer is offline Supersurfer  Netherlands
diyAudio Member
 
Join Date: Feb 2013
Quote:
Originally Posted by andrea_mori View Post
I wouldn't use the PC as the source so the USB is not practicable.

The Raspberry is a simple and cheap device to be used as a standalone source.

The problem is that the Raspberry generates a lot of EMI/RFI, so some precautions are mandatory (switch off BT and WiFi, keep the RPI far from the digital chain and so on).

Finally, if the FIFO does correctly its job nothing can pass from the source to the DAC. Otherwise, if the FIFO is source dependent IMHO there is somwthing wrong.

I see many members who struggle tweaking the Raspberry, using ultra low noise regulators to supply it or even removing the on board regulators.
But as I said several times IMHO the problem is not the RPI, the real problem is the FIFO that does not isolate the DAC from the source, that's the reason why we have choosen a totally different architecture.
If you succeed with a 100% isolation with your Fifo that would be awesome.

But as long as there is also sound quality to be gained with the use of special audio graded switches (Uptone Etherregen and the likes), better ethernet cables, better power supplies on your router and switch, closer positioning of your music carrying NAS to the streamer, I doubt your mission will succeed.
  Reply With Quote
Old 15th September 2020, 06:49 PM   #77
TNT is offline TNT  Sweden
diyAudio Member
 
Join Date: Apr 2003
Location: Sweden
Thats just an illusion or a very poor system in the end of that chain... I'm absolutely positive that with andreas solution in place, you wont hear any difference when changing the things you mention.

//
__________________
More distortion to the people! Time is paramount.
  Reply With Quote
Old 15th September 2020, 07:45 PM   #78
analog_sa is offline analog_sa  Europe
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Cascais
The Well synchronized asynchronous FIFO buffer - Slaved I2S reclocker
Quote:
Originally Posted by Supersurfer View Post
But as long as there is also sound quality to be gained with the use of special audio graded switches (Uptone Etherregen and the likes), better ethernet cables, better power supplies on your router and switch, closer positioning of your music carrying NAS to the streamer, I doubt your mission will succeed.

I am pretty certain no fifo can remove these effects. Their audibility is just not related to the data stream.
  Reply With Quote
Old 15th September 2020, 08:03 PM   #79
TNT is offline TNT  Sweden
diyAudio Member
 
Join Date: Apr 2003
Location: Sweden
Well, if its isolated via opto and distanced by a few meter, I cant see how that is possible. Please provide a technical explanation - I'm curious.

//
__________________
More distortion to the people! Time is paramount.
  Reply With Quote
Old 15th September 2020, 09:36 PM   #80
andrea_mori is offline andrea_mori  Italy
diyAudio Member
 
andrea_mori's Avatar
 
Join Date: Jan 2005
Location: Italy
Quote:
Originally Posted by analog_sa View Post
I am pretty certain no fifo can remove these effects. Their audibility is just not related to the data stream.
TNT has just well explained (I believe he is a RF man with the right skills), keep the source as far as possible from the DAC and then connect them via optic fiber and no EMI/RFI can affect the digital to analog conversion. Fiber optic cable is a real brickwall against ambient RF.

Only one signal has to be connected via copper, the most important for the DAC conversion, in our case the LRCK. It must be as free of jitter as possible since it drives the DAC switching.
Don't worry about the jitter coming from the optical connection, the other signals (BCK and DATA) does not affect the conversion, the only purpose of these signals is to load the registry of the DAC before the switching.

But if you continue to believe that the right way is to stack all the digital chain onto the Raspberry without any real isolation and feeding the DAC by the FPGA, then I agree, you have no chance to really isolate the DAC from the source, the FIFO will remain source dependent.

Keep in mind that using a FIFO the source and the DAC operate in different domains, so there is no reason for the DAC to be affected by the source, unless the system was not well designed.
Usually audible effects are related to poor isolation and poor clock.

I don't know if we will reach the target with our FIFO Lite, there are a few compromises to get it affordable, but I'm pretty sure we'll get there with the top version.
Surely the oscillators we have designed are a big step forward to reach the target.

Last edited by andrea_mori; 15th September 2020 at 09:41 PM.
  Reply With Quote

Reply


The Well synchronized asynchronous FIFO buffer - Slaved I2S reclockerHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Asynchronous DAC reclocker circuits ygg-it Digital Source 5 4th August 2018 06:35 AM
Ian's asynchronous FIFO kit Crom Swap Meet 2 13th October 2016 02:58 PM
FS: Ian's asynchronous FIFO buffer - a ton of stuff! NicMac Swap Meet 2 2nd October 2016 09:34 AM
Has anyone actually measured Elso's Asynchronous Reclocker? pop11 Digital Source 5 17th March 2004 02:09 PM


New To Site? Need Help?

All times are GMT. The time now is 02:41 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki