Low distortion, pure resistive I/V stage for Sabre Reference DAC - Page 4 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, 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 30th September 2012, 09:52 AM   #31
roender is offline roender  Romania
diyAudio Member
 
roender's Avatar
 
Join Date: Sep 2006
Schematic
Attached Images
File Type: jpg Latest Sabre iv.jpg (90.0 KB, 441 views)
  Reply With Quote
Old 30th September 2012, 06:11 PM   #32
orelli is offline orelli  Italy
diyAudio Member
 
Join Date: Aug 2008
Location: Correggio, Italia
Send a message via AIM to orelli Send a message via MSN to orelli Send a message via Yahoo to orelli
I'm not experienced like you, but I think the resistor values depending from the Idss of Jfets and hfe of BJTs to give the current that you want. For example the 2.5mA that polarize J1 and J2 are feed by CCS formed by J6 and J7 and R16 and R17. Right?
And 2.5mA depending by Idss and resistor value.
What's the Vout RMS in balanced mode? Of course with BIII?
Thanks for the quick reply.

Best, Orazio
  Reply With Quote
Old 1st October 2012, 05:26 AM   #33
roender is offline roender  Romania
diyAudio Member
 
roender's Avatar
 
Join Date: Sep 2006
You are correct in your assumptions related with biasing currents for CFP Njfet driver. In fact, you can choose jfets with 2.5mA idss and then not need any resistor for CCS current setting.
Vout[rms] = 650mV
  Reply With Quote
Old 1st October 2012, 11:17 AM   #34
orelli is offline orelli  Italy
diyAudio Member
 
Join Date: Aug 2008
Location: Correggio, Italia
Send a message via AIM to orelli Send a message via MSN to orelli Send a message via Yahoo to orelli
thank you very much.
  Reply With Quote
Old 31st October 2012, 02:20 AM   #35
2A3SET is offline 2A3SET  Canada
diyAudio Member
 
Join Date: Dec 2003
Location: Toronto
How about raising the ground reference to AVCC/2 to be compliant?

Quote:
Originally Posted by roender View Post
The offset voltage generated by the DAC do not mater. R14/19 are connected from the output of the DAC to ground.
This I/V stage can be seen as a microphone amplifier. The input resistor was increased to 2r2 in order to improve SNR to more than 125dB over 10-20kHz bandwidth. The Sabre Reference DAC is working now in "voltage mode" ... but is a voltage DAC anyway no mater what ESS is telling
  Reply With Quote
Old 31st October 2012, 06:58 AM   #36
roender is offline roender  Romania
diyAudio Member
 
roender's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by 2A3SET View Post
How about raising the ground reference to AVCC/2 to be compliant?
Would you please be more specific? Compliant with what?
What can be gained by rising the DAC output return to a steady potential of AVCC/2 than ground?
  Reply With Quote
Old 2nd November 2012, 08:47 PM   #37
diyAudio Member
 
Join Date: Jan 2011
Location: Germany
Nice IV converter!

I "hooked" it up in MicroCap10 Pro, and I have some issues with the lowish output voltage. It is ,when an ESS9018 is outputtting 16mA ACp-p + 8mA DC, only 0.4Vrms instead of the standardised 4 Vrms.

Do you also get 0,4Vrms at 0 dBFS?



/S

Quote:
Originally Posted by roender View Post
Schematic
  Reply With Quote
Old 2nd November 2012, 08:48 PM   #38
diyAudio Member
 
Join Date: Jan 2011
Location: Germany
Seems strange to me, too.

That would mean that the ESS9018 would not output any DC current (only AC current), right?


/S

Quote:
Originally Posted by roender View Post
Would you please be more specific? Compliant with what?
What can be gained by rising the DAC output return to a steady potential of AVCC/2 than ground?
  Reply With Quote
Old 5th November 2012, 04:51 AM   #39
roender is offline roender  Romania
diyAudio Member
 
roender's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by staccatiss View Post
Seems strange to me, too.

That would mean that the ESS9018 would not output any DC current (only AC current), right?


/S
I know what will happens if the output reference will be avcc/2, but is not clear what benefit will bring that.
  Reply With Quote
Old 5th November 2012, 05:12 AM   #40
roender is offline roender  Romania
diyAudio Member
 
roender's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by staccatiss View Post
Nice IV converter!

Do you also get 0,4Vrms at 0 dBFS?

/S
Nope ... should be around 600mV rms.
It is designed to be like that because my RMI-FC100 amp allow only 600mVpp at input for full output power.
  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
ESS Sabre Reference DAC VS Prism sound ADA-8XR, DAD AX24 and weiss DAC? mbl Digital Line Level 12 19th October 2009 09:48 AM


New To Site? Need Help?

All times are GMT. The time now is 04:31 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