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.

DSD adc
DSD adc
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 5th April 2017, 09:28 AM   #1
weroflu is offline weroflu  United States
diyAudio Member
 
Join Date: Dec 2014
Default DSD adc

I'm thinking about a stereo dsd adc using the pcm4222.

Does anyone know if this is a real dsd output with no decimation behind the scenes?

What is the smallest footprint toward capturing the dsd stream into a soc/small linux box/other small box?
  Reply With Quote
Old 5th April 2017, 01:51 PM   #2
lukaso25 is offline lukaso25
diyAudio Member
 
Join Date: Aug 2014
According to the PCM4222 datasheet, there is a DSD engine that converts multibit data into DSD (so there is some processing). The Delta Sigma modulators always run in multibit mode, because the device can outputs both format simultaneous.
  Reply With Quote
Old 9th December 2017, 07:19 PM   #3
alexcount is offline alexcount  United States
diyAudio Member
 
Join Date: Oct 2004
Location: NYC
Send a message via AIM to alexcount Send a message via Yahoo to alexcount DSD adc
Default The PCM4202 and PCM4204

As mentioned above, the PCM4222 is a multiple bit, multilevel Delta sigma architecture, and as the documentation states, the 1-bit DSD signal is truncated from this multibit bitstream.

The older PCM4202 and PCM4204 ADC's are internally a single bit Delta sigma architecture and output a pure and mathematically unmanipulated DSD signal, making them more appropriate for a DSD converter. I highly recommend for starting with these earlier ADC's, as they are easily obtained, well documented, and can achieve high quality results if great care in execution is taken regarding PCB design and layout, clock circuits and paths, and power supply's.

I have successfully used a PCM4202 for this purpose and found satisfactory audible improvements over PCM sampling with the same converter. This allowed me to record at 128fs or 5.6mhz.

You could achieve a very small footprint if everything was custom designed, but a lot of testing to ensure proper operation of all support components and minimal interference would be required unless utmost care in layout is taken.

The purpose-specific audio software/hardware interface for inputting a raw DSD bitstream into a *nix box is yet to be seen, unless done using general purpose hardware ( I.e. digital oscilloscope device and software, way more support hardware and software then necessary.) There is no open source software/hardware solution to this problem that I am aware of.

The output of DSD is possible now using a number if different open source libraries, but the capture of DSD is not yet a standard process and not standardized in almost any way. (Ayre QB-9/NuAudio phono converter seem to both support some kind of reverse version of the DoP standard but for recording.)
__________________
DIY DSD/DXD Blog
  Reply With Quote
Old 10th December 2017, 07:11 AM   #4
weroflu is offline weroflu  United States
diyAudio Member
 
Join Date: Dec 2014
That's great info on the pcm4202. I have also been curious about the non-native dsd stream of some newer adc's and what bearing it would have on the sound.

I have a lot of miniature power supplies already worked out here. Whether or not they are good enough or quiet enough to get into the digital world is another story. But I don't mind taking a stab at things and having it fail.

Shutterfly

do you have any thoughts on the ak557x series?

The summing mode is sort of tempting to get higher dynamic range, but then again anything over ~115db s/n seems fine for me as I'm not a low noise freak.

So it looks like the hardest part will be the coding and timing on the capture side of things. I'm curious about the recorder you built...
  Reply With Quote
Old 12th December 2017, 06:08 PM   #5
miro1360 is offline miro1360  Europe
diyAudio Member
 
Join Date: Mar 2010
and what about SAR ADC?
  Reply With Quote
Old 12th December 2017, 09:55 PM   #6
MarcelvdG is offline MarcelvdG  Netherlands
diyAudio Member
 
Join Date: Mar 2003
Location: Haarlem, the Netherlands
A SAR ADC by definition produces PCM rather than DSD. DSD is a trade name for a single-bit sigma-delta modulate, so if you don't want any conversions, you need a single-bit sigma-delta modulator to generate it.
  Reply With Quote
Old 12th December 2017, 10:50 PM   #7
miro1360 is offline miro1360  Europe
diyAudio Member
 
Join Date: Mar 2010
I asked why not SAR/PCM rather than DSD ...
Direct Stream Digital - Wikipedia
I have read that few valuable recording companies moved back to SAR - from not trusted source (google )
  Reply With Quote
Old 13th December 2017, 05:09 AM   #8
xx3stksm is offline xx3stksm  Japan
diyAudio Member
 
xx3stksm's Avatar
 
Join Date: Jun 2017
Location: Hokkaido(north area)
DSD adc
It's a historical issue, IMHO. When digital recording started in 80's, you had no choice except PCM ADC, no available DSM ADC those days. But PCM ADC was not excellent compared with recent one. From 90's, You were able to use DSM ADC which were superior to PCM, then DSM became the standard ADC for many years.

But these days silicon industry has invented another high-performance PCM ADC called SAR which can operate more than 10MHz at 18bit resolution. Latest SAR is superior to DSM, especially in SNR. Now we have two selections SAR and DSM. It's subjective decision which you like and select.
  Reply With Quote
Old 13th December 2017, 06:32 AM   #9
Trajan is offline Trajan  United States
diyAudio Member
 
Join Date: Apr 2014
More info on SAR? Technical papers please.
  Reply With Quote
Old 14th December 2017, 04:37 AM   #10
xx3stksm is offline xx3stksm  Japan
diyAudio Member
 
xx3stksm's Avatar
 
Join Date: Jun 2017
Location: Hokkaido(north area)
DSD adc
Some information about SAR, though a little bit off the thread. The latest SAR(AD7960) has almost same DR and SNR. DR is usually measured at -60dBFS and SNR at -1dBFS.
http://www.analog.com/media/en/techn...h=%27ad7960%27
Figure 12 at page10 shows SNR with 2500kHz bandwidth as 99.8dB. If you use this with 25kHz bandwidth, you can get 99.8+10log (100)=119.8dB.

I have the EV-board for AD9760. It has almost same value as the datasheet says. DSM ADC usually has noise increase at -1dBFS by 6dB. That's why both have almost same DR, but SAR has better SNR than DSM.
AFAIK, AD7768 is a candidate to compete with AD7960. AD7768 has 8 DSM ADCs which can operate together for better SNR and has less degradation at -1dBFS. But eight ADC drivers mean the disadvantage of PCB layout and clean power supply. My conclusion so far is that SAR is better than DSM if you want high SNR.
  Reply With Quote

Reply


DSD adcHide 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
SAR ADC for high performance audio ADC project [LTC2380-24] Frex Equipment & Tools 219 Today 08:28 AM
Something cool for Raspberry Pi/ODROID: I2S/DSD isolator HAT with native DSD decoder iancanada PC Based 368 8th November 2018 03:05 PM
DSD Playback system, DSF Player + USB DDC + DSD Amplifier KOON3876 Digital Source 120 14th November 2017 08:25 AM
USB DSD DAC and ADC by ElectrArt alexcount Digital Source 70 15th May 2014 01:30 PM
Buffers for ADC design with AK5394A and other ADC's ? JensH Equipment & Tools 66 20th December 2013 08:29 AM


New To Site? Need Help?

All times are GMT. The time now is 04:04 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki