Anyone built a Pass D1 I/V for a TI1794 or TI1794 DAC? - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 May 2006, 03:15 AM   #1
diyAudio Member
 
hifimaker's Avatar
 
Join Date: Oct 2003
Location: San Jose
Default Anyone built a Pass D1 I/V for a TI1794 or TI1794 DAC?

I understand that the current output of the TI1792 DAC chip is higher than other DACs. Has anyone had success buildign a D1 I/V for these newer TI DAC chips?

-David
  Reply With Quote
Old 6th May 2006, 07:04 PM   #2
diyAudio Member
 
hifimaker's Avatar
 
Join Date: Oct 2003
Location: San Jose
The specs on this BB/TI 1792/4 chip look great. I'm surprise no one has implemented a DAC with a Pass I/V stage yet.

-David
  Reply With Quote
Old 6th May 2006, 09:56 PM   #3
diyAudio Member
 
Join Date: Jun 2002
Location: Italy
I love D1 stage . And implementet at least with 4 dacs . Will need to modify the biasing network a bit if the dc point of the dac is different from 0 volt . An example is the Philips tda 1545 wich requires 3.3 volts as dc working point.
Currently I am using the lovoltech j fet in that circuit . I am very happy .
  Reply With Quote
Old 6th May 2006, 10:11 PM   #4
acaudio is offline acaudio  Germany
diyAudio Member
 
Join Date: Sep 2004
Location: Germany
Stefano,

Im currently building my D1 stage with different options.
Im still no really lucky. my CDP (shanling CD-S100MK2) has a PCM1738 inside. This chip seems to work best into a "virtual" ground, the common Voltage is set to 2,50V.
See this picture, and thread: http://www.diyaudio.com/forums/attac...amp=1081271528
D1 output stage and PCM1738
I tried already a few different adjustments and I thought it were good, but after long listening Im sure, Im missing dynamic.
Would you please posting your lovoltech D1? Im working at a 2SK389 based D1, very different to original. I thought too about LU1014d, but those needs a lot of current to operate in "triode region"
Best Regards
Adam
__________________
http://www.acaudio.de
  Reply With Quote
Old 7th May 2006, 01:50 PM   #5
diyAudio Member
 
Join Date: Jun 2002
Location: Italy
No, really also in a single ended set up I like dynamics , very correct . But compressions and dynamics depends on power supplies implementation and a number of other things.
With j fet (lovoltech)there is a step forward by my point of view ,and often I can see the mixing consolle very clearly . It is a nice sensation .
I wasnt so happy with 2sk s .
Absolutely the lovoltech require matching between channels . The difference is quite audible and not at all subtle.

I started by inserting jfets in the same circuit , just adjusting the bias ... and all seems to work pretty well .
  Reply With Quote
Old 7th May 2006, 05:21 PM   #6
diyAudio Member
 
hifimaker's Avatar
 
Join Date: Oct 2003
Location: San Jose
Quote:
Originally posted by stefanobilliani
No, really also in a single ended set up I like dynamics , very correct . But compressions and dynamics depends on power supplies implementation and a number of other things.
With j fet (lovoltech)there is a step forward by my point of view ,and often I can see the mixing consolle very clearly . It is a nice sensation .
I wasnt so happy with 2sk s .
Absolutely the lovoltech require matching between channels . The difference is quite audible and not at all subtle.

I started by inserting jfets in the same circuit , just adjusting the bias ... and all seems to work pretty well .

Thanks Stefano for your insights.

Could I ask, what DAC are you using?

-David
  Reply With Quote
Old 7th May 2006, 05:38 PM   #7
diyAudio Member
 
Join Date: Jun 2002
Location: Italy
hehehe I have the Philips tda15145 but every part of the circuitry has separated supplies , laser motors drivers and clock included .
I can assure you that it works very very good .
I had also nice performances with sony current pulse , in that case in a balanced configuration .
The philips is 16 bit converter , sony is tipically 1 bit.
  Reply With Quote
Old 8th May 2006, 03:46 AM   #8
agent.5 is offline agent.5  United States
diyAudio Member
 
Join Date: Aug 2003
Location: San Francisco, CA
Quote:
Originally posted by stefanobilliani
I love D1 stage . And implementet at least with 4 dacs . Will need to modify the biasing network a bit if the dc point of the dac is different from 0 volt . An example is the Philips tda 1545 wich requires 3.3 volts as dc working point.
Currently I am using the lovoltech j fet in that circuit . I am very happy .
Assuming that I have 0 volt out from the DAC, what do I have to change to the circuit to use Lovoltech Jfet instead of IRF610. My thinking is that I need to change the two 1.5K resistors to a different value to bias the Jfet? The schematic that I am looking at is attached.
Attached Images
File Type: jpg d1schematic.jpg (86.1 KB, 2892 views)
  Reply With Quote
Old 8th May 2006, 10:37 PM   #9
diyAudio Member
 
relder's Avatar
 
Join Date: Jan 2002
Location: Tucson, AZ
Blog Entries: 14
Send a message via Yahoo to relder
Quote:
Originally posted by agent.5


Assuming that I have 0 volt out from the DAC, what do I have to change to the circuit to use Lovoltech Jfet instead of IRF610. My thinking is that I need to change the two 1.5K resistors to a different value to bias the Jfet? The schematic that I am looking at is attached.
JFET Vgs is negative, unlike MOSFET, so instead of tying r5a to +30 tie it to -30. The 1.5K resistors control gain, not bias, to change current bias change the 3.3K resistor.
  Reply With Quote
Old 8th May 2006, 11:19 PM   #10
diyAudio Member
 
hifimaker's Avatar
 
Join Date: Oct 2003
Location: San Jose
I seem to recall someone built a D1 I/V stage with Jfets recently, Let me see if I can find it.

Would be very cool.

-David
  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
DIY Low Pass and Mid/High Pass (Bass Blocking) Filters runslikealpaca Everything Else 1 19th June 2009 11:59 PM
Paging Mr. Pass, Mr. Pass pull my finger please. khundude Pass Labs 2 5th December 2008 05:11 AM
Question about power amp built in high pass filter crippledchicken Solid State 0 22nd October 2008 07:09 PM
non-Pass amps youv'e built/heard BrianL Solid State 49 5th July 2005 06:59 AM
My opinion on Pass Labs and Mr. Pass (Nelson) himself b_online Pass Labs 11 21st May 2003 01:39 AM


New To Site? Need Help?

All times are GMT. The time now is 09:56 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