Using the AD844 as an I/V - Page 87 - 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 20th June 2014, 06:09 AM   #861
diyAudio Member
 
Join Date: Jun 2007
Thanks George - it may get a little messy on the PCB. Is it possible to 'steal' the I signal (pin 14) from the PCM1704 and run it to a separate board I make for the AD844? Or will it load the dac chip too much (if I leave the OPA627 unchanged)?
  Reply With Quote
Old 20th June 2014, 09:25 AM   #862
diyAudio Member
 
georgehifi's Avatar
 
Join Date: Sep 2003
Location: Manly Australia (Jewel of the Pacific)
Send a message via MSN to georgehifi
Yes you can do that, but you'll have to cut the track that goes from pin 14 of the PCM1704 to the OPA627.

Cheers George
__________________
Avatar : Production Lightspeed Attenuator
www.lightspeedattenuator.com
  Reply With Quote
Old 25th June 2014, 10:31 AM   #863
supra is offline supra  Australia
diyAudio Member
 
Join Date: Jul 2004
Location: Margaret River West Australia
I just built a 9018 dac with all of Ian's FIFO, isolater, clock etc and although it was very good, after a few days found it just too much like a Sabre dac, very accurate, highly technical but a bit soulless . Tried a nomber of I/V but eventually put an OPA861 on output.
Fixed it, enjoyable to listen to now, very close to my 1541 with stacked 844 in terms of musicality .
These trans conductance devices are something else, Pedja was on the money when he starting using them.
  Reply With Quote
Old 26th June 2014, 07:17 AM   #864
diyAudio Member
 
georgehifi's Avatar
 
Join Date: Sep 2003
Location: Manly Australia (Jewel of the Pacific)
Send a message via MSN to georgehifi
Quote:
Originally Posted by supra View Post
I just built a 9018 dac with all of Ian's FIFO, isolater, clock etc and although it was very good, after a few days found it just too much like a Sabre dac, very accurate, highly technical but a bit soulless . Tried a nomber of I/V but eventually put an OPA861 on output.
Fixed it, enjoyable to listen to now, very close to my 1541 with stacked 844 in terms of musicality .
These trans conductance devices are something else, Pedja was on the money when he starting using them.
Ditto,
And if you do Abraxalito's bipolar 10uf 50v smd cap mod from + to - rail on the AD844 and on whatever buffer your using, you'll pick up a little more.
Using the AD844 as an I/V

Cheers George
__________________
Avatar : Production Lightspeed Attenuator
www.lightspeedattenuator.com
  Reply With Quote
Old 2nd July 2014, 11:00 PM   #865
diyAudio Member
 
georgehifi's Avatar
 
Join Date: Sep 2003
Location: Manly Australia (Jewel of the Pacific)
Send a message via MSN to georgehifi
After listening now for a while to Abraxalito's mod above, I can say it's very good in a subtle way. There is now a cleaner sense to the music, and the mirco detail is the most improved area.
Abraxalito can you give some techincal explanation on what happens, when your mod is in place, as I've look at it on the bench tests and there is nothing I can pick up on???


Cheers George
__________________
Avatar : Production Lightspeed Attenuator
www.lightspeedattenuator.com
  Reply With Quote
Old 2nd July 2014, 11:23 PM   #866
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
I haven't any technical measurements to back it up but it seems that its reducing the noise generated by the AD844 itself on its power rails. The self-generated noise is an issue for all circuits not running in pure classA in that there's a current taken which varies with the signal. The output stage is the biggest generaor of noise and this noise will depend on the load - the current drawn by the IC under load looks like a half-wave rectified version of the signal. So its frequency content is higher than the original signal, hence the need for higher frequency decoupling, beyond the audio band.
__________________
It doesn't have to take the form of a conspiracy, rather a consensus... James H Kunstler
  Reply With Quote
Old 5th July 2014, 01:53 PM   #867
StevieK is offline StevieK  Germany
diyAudio Member
 
Join Date: Dec 2009
Default Voltage- Input instead of CCs in Orginal circuit

Hello,
I got an Idea on the orgin circuit, so there is put CCS in the AD844, is it posible to
put voltage on the voltage Input and leave out the CCS to get zero Voltage at the
Output?
  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
AD844 as a common base stage in the I/V converter Pedja Digital Source 42 25th March 2013 07:56 AM
WTB AD844 Opamps apassgear Swap Meet 6 31st January 2007 02:57 PM


New To Site? Need Help?

All times are GMT. The time now is 12:01 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