AD1865 schematic - Page 2 - 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 22nd December 2012, 04:08 PM   #11
regal is offline regal  United States
diyAudio Member
 
Join Date: Jan 2004
Location: MD
With this design there's going to be inevitably a lot of jitter, the cs8416 spdif plus the glue logic...


Did you see the iancanda board at the top of the page, its ideal for AD1865 because it does the delay/conversion and synchs the clocks for you with the lowest jitter possible also would allow the option to try other R2R chips in NOS mode with protoboards like the one abraxilito posted (I just ordered 4 of those they look great.)
  Reply With Quote
Old 22nd December 2012, 04:42 PM   #12
diyAudio Member
 
skouliki's Avatar
 
Join Date: Aug 2010
Location: Athens
Yes FIFO would be great, but i cannot really afford it right now.
  Reply With Quote
Old 23rd December 2012, 10:26 AM   #13
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 98
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Not really worth worrying too much about jitter - I don't find it a problem in terms of the subjective SQ when running multibit DACs. Definitely though its an issue on S-D DACs. Rather worry about reducing noise modulation, that's the biggest detractor from SQ.
__________________
It doesn't have to take the form of a conspiracy, rather a consensus... James H Kunstler
  Reply With Quote
Old 23rd December 2012, 12:43 PM   #14
regal is offline regal  United States
diyAudio Member
 
Join Date: Jan 2004
Location: MD
Quote:
Originally Posted by abraxalito View Post
Not really worth worrying too much about jitter - I don't find it a problem in terms of the subjective SQ when running multibit DACs. Definitely though its an issue on S-D DACs. Rather worry about reducing noise modulation, that's the biggest detractor from SQ.
What do you think about this schematic, is it worth adding the extra noise to align the channels ?
  Reply With Quote
Old 23rd December 2012, 01:51 PM   #15
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 98
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
You mean is it worth adding a long shift reg? I doubt I'd bother - the delay of one sample I don't think is audible. I would though on that circuit prefer to run the HC logic at 2.5V rather than 5V. If you added an HEF4517 to do the shifting, I doubt that would add much noise though, being 4000 series, the slowest known CMOS
__________________
It doesn't have to take the form of a conspiracy, rather a consensus... James H Kunstler
  Reply With Quote
Old 23rd December 2012, 02:13 PM   #16
regal is offline regal  United States
diyAudio Member
 
Join Date: Jan 2004
Location: MD
Quote:
Originally Posted by abraxalito View Post
You mean is it worth adding a long shift reg? I doubt I'd bother - the delay of one sample I don't think is audible. I would though on that circuit prefer to run the HC logic at 2.5V rather than 5V. If you added an HEF4517 to do the shifting, I doubt that would add much noise though, being 4000 series, the slowest known CMOS
Yes that's what I meant, I can hear the delay with headphones. One thing I'm not sure of in these schematics is he calls for 24 bit I2s, but most I2S output USB stuff use a 256x clock. I think its a gotcha if anyone is planning on using these with a usb-i2s device.
  Reply With Quote
Old 23rd December 2012, 05:50 PM   #17
diyAudio Member
 
skouliki's Avatar
 
Join Date: Aug 2010
Location: Athens
Quote:
Originally Posted by abraxalito View Post
You mean is it worth adding a long shift reg? I doubt I'd bother - the delay of one sample I don't think is audible. I would though on that circuit prefer to run the HC logic at 2.5V rather than 5V. If you added an HEF4517 to do the shifting, I doubt that would add much noise though, being 4000 series, the slowest known CMOS
So the optimal voltage for 74HCT164 in that circuit is 2.5v. Can you explain why? Sorry, im kinda clueless
  Reply With Quote
Old 23rd December 2012, 08:55 PM   #18
diyAudio Member
 
Join Date: May 2010
Quote:
Originally Posted by abraxalito View Post
You mean is it worth adding a long shift reg? I doubt I'd bother - the delay of one sample I don't think is audible. I would though on that circuit prefer to run the HC logic at 2.5V rather than 5V. If you added an HEF4517 to do the shifting, I doubt that would add much noise though, being 4000 series, the slowest known CMOS [IMG]file:///C:/Users/jb/AppData/Local/Temp/msohtmlclip1/01/clip_image001.gif[/IMG]
A design goal of Pavouk's DAC is 192K operation. The HEF4517 is too slow, as Pavouk found out. At 2.5V the HC164 is not fast enough, either. Besides, shifting the data will have little impact on sample clock jitter. Even though BCK is driving seven loads, it is of little consequence. With the AD1865, the low-going latch edge updates the respective DAC output. Most other DACs update on a rising BCK edge.
  Reply With Quote
Old 23rd December 2012, 09:00 PM   #19
regal is offline regal  United States
diyAudio Member
 
Join Date: Jan 2004
Location: MD
Quote:
Originally Posted by Tam Lin View Post
Even though BCK is driving seven loads, it is of little consequence. With the AD1865, the low-going latch edge updates the respective DAC output. Most other DACs update on a rising BCK edge.
That's interesting to know could this be one reason why the AD1865 is more popular than the seemingly identical the PCM56k/PCM58k
  Reply With Quote
Old 23rd December 2012, 11:37 PM   #20
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 98
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by skouliki View Post
So the optimal voltage for 74HCT164 in that circuit is 2.5v. Can you explain why? Sorry, im kinda clueless
Its not HCT, that wouldn't work at 2.5V, its HC. As Tam Lin has pointed out that 192k operation was desired by the originator, then he might indeed be correct about the speed of the HC164 not being sufficient at 2.5V; however I'd not recommend running a DAC at 192k. Its throwing away some of the advantage of using the AD1865 to run it so fast and there's no audio benefit, only detraction of running at such a high SR.

The reason to reduce the supply is to keep the power supply noise low as noise is enemy no.1 to decent sound. The edge speeds reduce nicely at such a low supply voltage.
__________________
It doesn't have to take the form of a conspiracy, rather a consensus... James H Kunstler
  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
AD1865 vs AD1955 toufu Digital Line Level 50 15th April 2012 01:59 AM
Schematic for AD1865 ebay dac? mkanna Digital Line Level 1 13th May 2011 03:26 AM
AD1865-based dac schematic Sandor Digital Line Level 8 16th March 2010 07:01 PM
AD1865 w/ USB? dsavitsk Digital Source 6 28th February 2006 10:47 AM
AD1865 where? avian Digital Source 2 5th January 2004 07:17 AM


New To Site? Need Help?

All times are GMT. The time now is 03:07 PM.


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