Experience with this DIY DAC ? - Page 141 - 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 25th October 2009, 02:49 PM   #1401
diyAudio Member
 
Join Date: Jan 2009
Hello McGyver,
Other than learning Polish do you know where/how I could order one of these?
  Reply With Quote
Old 25th October 2009, 03:29 PM   #1402
legarem is offline legarem  Canada
diyAudio Member
 
legarem's Avatar
 
Join Date: Jan 2005
Location: Quebec city
What is bothering me with this PCM1798 board is the two op amps we see under the board. I want to get rid of op amps. Op amp are devil for me.
  Reply With Quote
Old 25th October 2009, 03:56 PM   #1403
McGyver is offline McGyver  Poland
diyAudio Member
 
McGyver's Avatar
 
Join Date: Nov 2004
Location: Poland
Quote:
Originally Posted by legarem View Post
What is bothering me with this PCM1798 board is the two op amps we see under the board. I want to get rid of op amps. Op amp are devil for me.
But I did it. I got rid of opamps, I desoldered them and connected transformers right to the chip's legs. And grounded center taps.
  Reply With Quote
Old 25th October 2009, 05:40 PM   #1404
Lucas_G is offline Lucas_G  Netherlands
diyAudio Member
 
Join Date: Nov 2002
Location: Netherlands
Default Frequency Response with Lundahl 1674

I am listening to my DAC with Lundahl LL 1674 for some weeks now.
I attach a picture with how I connected the Lundahls. I use two 1K resistors for R1 and R2 and no resistor for R3.
I also have a 1nF MKP cap connected between the output sides of R1 and R2 as a very light filter for high frequencies at the input side of the Lundahls.

Today I measured the output of this configuration, and I wasn't pleased to see the frequency response. As you can see on the picture, already at 20 kHz the level is down by some -6 dB

These Lundahls should be quite flat up to 20 kHz, so apparently my connection is not optimal.

Can anyone give me a clue as to get better results?
Attached Images
File Type: jpg Lundahl1674connection.jpg (22.9 KB, 643 views)
File Type: jpg FrequenceFromDacwithLL1674.jpg (79.2 KB, 635 views)
  Reply With Quote
Old 25th October 2009, 05:58 PM   #1405
Tony X is offline Tony X  France
diyAudio Member
 
Tony X's Avatar
 
Join Date: Dec 2007
Thanks, Havoc08, for directing me to this thread. It's taken me about three days to read and although I cannot pretend to understand everything, I am convinced already go the transformer route. Which transformers is a decison yet to be made.

It still looks to me, however, that the DAC you suggested is a baby brother to the ones talked about here.

I don't see any obvious reason they shouldn't, but can someone please confirm that these mods also apply to this DAC.

My aim is to place this DAC between a Shigaclone (still to be built) and a MyRef amp via a Lightspeed attenuator and finally going into 98db full range speakers.

I also have a T-Amp which I like to use during trials. Are we saying here that the T Amp needs a special arrangement and so we cannot just swop amps around ?
  Reply With Quote
Old 25th October 2009, 07:29 PM   #1406
Tony X is offline Tony X  France
diyAudio Member
 
Tony X's Avatar
 
Join Date: Dec 2007
Although I have the DAC mentioned in the previous post on order, I had been looking at this one which is locally available. As it is PCM1798 based, I thought it might be of interest seen McKyver's recent comments. It even has a Chinese price and might have originated there for all I know.

SPDIF only!!

Anybody have any experience with this one?

Last edited by Tony X; 25th October 2009 at 07:32 PM.
  Reply With Quote
Old 25th October 2009, 08:23 PM   #1407
McGyver is offline McGyver  Poland
diyAudio Member
 
McGyver's Avatar
 
Join Date: Nov 2004
Location: Poland
Quote:
Originally Posted by Tony X View Post
Although I have the DAC mentioned in the previous post on order, I had been looking at this one which is locally available. As it is PCM1798 based, I thought it might be of interest seen McKyver's recent comments. It even has a Chinese price and might have originated there for all I know.

SPDIF only!!

Anybody have any experience with this one?
Looks good, nice layout and quality components. But Yoy should bear in mind that PCM1798 is not a voltage output DAC. It is a current output DAC, and requires completely different analogue stage than CS4397 or CS4398.
For PCM1798 I'm using Sowter transformers for I/V conversion, desymmetrization and analogue filtration followed by tube amplification stage.
  Reply With Quote
Old 25th October 2009, 08:39 PM   #1408
Ryssen is offline Ryssen  Sweden
diyAudio Member
 
Ryssen's Avatar
 
Join Date: Dec 2003
Location: Sweden--> Here
McGyver,I contacted you via your website,regarding the PCM1798.

[QUOTEFor PCM1798 I'm using Sowter transformers for I/V conversion, desymmetrization and analogue filtration followed by tube amplification stage.
][/QUOTE]
Do you have a drawing how this is done?
__________________
Regards ke
  Reply With Quote
Old 25th October 2009, 08:58 PM   #1409
McGyver is offline McGyver  Poland
diyAudio Member
 
McGyver's Avatar
 
Join Date: Nov 2004
Location: Poland
No, I haven't. I just soldered it. I must draw it and post it here.
  Reply With Quote
Old 25th October 2009, 09:02 PM   #1410
Tony X is offline Tony X  France
diyAudio Member
 
Tony X's Avatar
 
Join Date: Dec 2007
Quote:
Originally Posted by McGyver View Post
PCM1798 is not a voltage output DAC. It is a current output DAC,
OK Thanks
  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
A.O.S - Any experience? Keltern Multi-Way 16 26th April 2012 11:15 PM
my t-amp experience Eggzy Chip Amps 35 17th December 2005 06:29 PM


New To Site? Need Help?

All times are GMT. The time now is 05:26 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