DAC With No Output Stage - 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 31st May 2012, 01:55 AM   #1
diyAudio Member
 
Join Date: Jan 2008
Location: Bountiful, You-Taw
Default DAC With No Output Stage

I have been building a CS-4398 DAC that has no output stage. It uses instead a pair of Lundahl transformers driven directly off the output of the DAC itself. The one I have here that is now running sounds unbelievable, convincing me beyond a doubt that no output stage is the better choice. These transformers are hard to argue with and actually have a better frequency response and less phase shift and certainly less distortion than do most high end circuits typically found in use for this purpose. I highly reccomend it and although the cost is a bit high for the transformers you certainly won't be disappointed. Has anyone else tried this or built a DAC this way yet?

Mark
  Reply With Quote
Old 31st May 2012, 02:13 AM   #2
diyAudio Member
 
Join Date: Mar 2012
Location: Melbourne
Quote:
Originally Posted by Mark Allen View Post
I have been building a CS-4398 DAC that has no output stage. It uses instead a pair of Lundahl transformers driven directly off the output of the DAC itself. The one I have here that is now running sounds unbelievable, convincing me beyond a doubt that no output stage is the better choice. These transformers are hard to argue with and actually have a better frequency response and less phase shift and certainly less distortion than do most high end circuits typically found in use for this purpose. I highly reccomend it and although the cost is a bit high for the transformers you certainly won't be disappointed. Has anyone else tried this or built a DAC this way yet?

Mark
Yep, I've been running this configuration for over 10 years - it was a published DIY tweak back then and was popular in my local DIY group. I used to have have a Cirrus Logic demo board, CS4390 (24 bit/48kHz), the demo board was nice enough to have convenient test points straight off the DAC output which I fed into a Lundahl 1527XL tranny. In 2004 I updated to a CS4398 demo board, and transferred the tranny's to this new DAC. It sounds excellent, and I agree that no output stage is better than any active stage. The trannies are now around $95 each in Australia, but its still way cheaper than building a valve output stage. A solid state stage could be built for less than $200 but not sure that it would sound as good as this.
  Reply With Quote
Old 31st May 2012, 02:30 AM   #3
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Me too, for several years. Just about everything but Lundhal. I love it. The Cirrus chips seem particularly happy with a transformer output.

It's easy and sounds great. Measures well, too.
  Reply With Quote
Old 31st May 2012, 02:02 PM   #4
Ryssen is offline Ryssen  Sweden
diyAudio Member
 
Ryssen's Avatar
 
Join Date: Dec 2003
Location: Sweden--> Here
Quote:
It uses instead a pair of Lundahl transformers driven directly off the output of the DAC itself.
What Lundahl trafo are you using?
__________________
Regards Åke
  Reply With Quote
Old 31st May 2012, 02:23 PM   #5
diyAudio Moderator Emeritus
 
jean-paul's Avatar
 
Join Date: Sep 2002
Location: Germany
Me too. I used Haufe and Neutrik transformers with very good results. Since ES9023 and FN1242a both can not drive these transformers as well as I would like them to I am selling a few of those boards in the Swap Meet.

CS4397/8 sound the best with transformers IMO.
__________________
It's only audio. Official member of the Norske Brillegeit Gang.
  Reply With Quote
Old 31st May 2012, 02:40 PM   #6
diyAudio Member
 
Join Date: Feb 2004
Location: Elst
Default TDA1541A + transformers

Hi Mark,

same here ! Although i use the TDA1541A as DAC....i also prefer the transformer output stage.

In the DIY-kit there was an opamp option (AD844) and a tube option (6DJ8 or 6C45) but both are inferior to good transformers. First i used "basic" transformers and that was already serious good. Then i found Silvercore (www.silvercore.de) who made 1:20 steup-ups for me....really great !

Included some pictures of the DAC-PSB (yes....currently plain in the open and ABSOLUTELY no hummmmmm). The 2 small coils you will notice on one side of the PCB are actual home made I/V-resistors.
The stainless steel casings are the Silvercore trannies.

Regards, Reinout
Attached Images
File Type: jpg X+I-2 001.jpg (412.6 KB, 1179 views)
File Type: jpg IMG_6621.JPG (377.1 KB, 1132 views)
File Type: jpg IMG_6634.JPG (322.5 KB, 1116 views)
  Reply With Quote
Old 1st June 2012, 12:45 AM   #7
diyAudio Member
 
Join Date: Jan 2008
Location: Bountiful, You-Taw
Quote:
What Lundahl trafo are you using?
The LL-1690 line transformer. I mean this DAC is absolutely stunning and I can't see why people waste their time doing anything else. The dac uses a CS-8416 input receiver... CS8421 Sample rate converter and a CS-4398 DAC all in TSSOP packages. It's all surface mount stuff for the most part but I'm used to SMT so no big deal. I can't post the schematic because I am not the designer. I was lucky enough to get one pcb from him. There is a link to what the prototype looks like here... CS4398 DAC
Note that mine is slightly different, this is the prototype board. The Lundahl's are 148 USD each in the States. Pricy but well worth it!
Mark

Last edited by Mark Allen; 1st June 2012 at 12:50 AM. Reason: Added tranny pricing.
  Reply With Quote
Old 20th June 2013, 08:13 PM   #8
diyAudio Member
 
Join Date: Feb 2009
Unhappy Audio Dac CS4390 with lundahl LL1527 output transformers

Hi...
...I just saw this thread and want to ask for some help.I just buy a pair of this Lundahl transformers and made a passive output for my dac.I just pick up direct analog out from dac legs and feed this to Lundahl transformers in serial 1+1:1+1!!.But I dont know if I need some load resistor on the secondary(output) side of the transformers.The signal will go from dac to my solid state amp that have 20 Kohm input impedance.Plese for help.Im dealing for the first time with transformers on output.
  Reply With Quote
Old 21st June 2013, 10:14 PM   #9
diyAudio Member
 
Join Date: Jul 2011
Location: Prior Lake, MN
Thumbs up Transformer output

Yes... I am doing this too. I have the Sheldon Stokes CS8416/CS8421/CS4398 with the LL1690's. Nice. Also got awesome results with a TDA1541A S1 Crown dac using Edcor XSM 600/600 transformers after the I/V. Here is a link to that.... DAC build TDA1541A/SAA7220P/B *will take som time* My TDA is my best dac to date.
  Reply With Quote
Old 21st June 2013, 11:59 PM   #10
diyAudio Member
 
Join Date: Jun 2003
Location: Hamilton, was Ottawa (Canada)
Quote:
Originally Posted by hazard500 View Post
Yep, I've been running this configuration for over 10 years - it was a published DIY tweak back then and was popular in my local DIY group. I used to have have a Cirrus Logic demo board, CS4390 (24 bit/48kHz), the demo board was nice enough to have convenient test points straight off the DAC output which I fed into a Lundahl 1527XL tranny. In 2004 I updated to a CS4398 demo board, and transferred the tranny's to this new DAC. It sounds excellent, and I agree that no output stage is better than any active stage. The trannies are now around $95 each in Australia, but its still way cheaper than building a valve output stage. A solid state stage could be built for less than $200 but not sure that it would sound as good as this.

Give it up for da man!

Andrea Ciuffoli DAC 1.0

dac2.gif

DAC 1.0

Old school, baby!
  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
dac output stage lt cdr data Digital Source 2 19th May 2005 11:07 PM
Dac output stage ?? Chris Digital Source 29 16th March 2003 08:20 AM
output stage for dac Jaap Digital Source 0 23rd February 2003 07:09 PM
DAC output stage Freddie Solid State 20 3rd August 2002 05:20 PM


New To Site? Need Help?

All times are GMT. The time now is 08:12 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