Output DAC - 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 23rd September 2010, 12:05 AM   #1
diyAudio Member
 
Join Date: Nov 2008
Location: Brazil
Default Output DAC

Hi

I have the player Philips CD610 and want to replace OPAMPS and put in common GND with the output of the transformer, but I know little about DAC. I wonder what the function of trasistors the output of opamp?

Attached scheme:
Attached Images
File Type: png Captura_de_tela.png (186.0 KB, 171 views)
  Reply With Quote
Old 23rd September 2010, 05:10 PM   #2
guido is offline guido  Netherlands
diyAudio Member
 
guido's Avatar
 
Join Date: Mar 2002
Location: diepe zuiden
mute function
__________________
GuidoB
  Reply With Quote
Old 24th September 2010, 06:19 PM   #3
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Don't understand the "transformer gnd" bit. What do you mean.

As Guido says, four transistors at the right are muting. Middle two are deemphasis switching.

Swapping the opamps would be worthwhile... and being very boring I'll still suggest OPA2604 although you may want to try the LM4562.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 24th September 2010, 09:54 PM   #4
diyAudio Member
 
Join Date: Nov 2008
Location: Brazil
Quote:
mute function
Quote:
As Guido says, four transistors at the right are muting. Middle two are deemphasis switching.
The circuit is confusing to me, the transistor on the left I think the are two filters, one is active by switching transistor.

Quote:
Middle two are deemphasis switching
Not understand

The 22k resistor (3675,3676) before the two transistors mute funcion, I seem to make a voltage divider, more leaves to very high output impedance.

Quote:
suggest OPA2604 although you may want to try the LM4562.
I was thinking of using the OPA2134, The opamp OPA2604 would be a better option?

Quote:
Don't understand the "transformer gnd" bit. What do you mean.
Is to put the preamp and CD player in even GND to avoid a ground loop, see figure.
Attached Images
File Type: jpg Gnd.jpg (38.4 KB, 99 views)
  Reply With Quote
Old 25th September 2010, 06:38 AM   #5
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
The 22k resistors reference the output electroylitic and mute transistors to ground. Common practice to do that. The resistor is high enough to have no effect on the output at all as it's fed from the opamp output.

The mute transistors, two are used per channel to get a "deep" enough level of muting in conjunction with the 470 ohm resistors. These two 470 ohm in series define the output impedance of the player.

The deemphasis transistors are the two in front of the opamp that change the hf filter characteristics.

All the transistors and diodes at the top are used to provide the logic levels required to operate the mute and deemphasis circuits.

The OPA2604 is just a personal favourite I find works well
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  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
How to specify a transformer for dac output? sharpi31 Digital Line Level 12 3rd March 2010 09:15 PM
dac - passive output ? 2cc Digital Source 1 18th October 2008 04:43 AM
Converting Dac-in-the-box's DAC chip to I/V output Aleksunder Digital Source 0 22nd January 2007 12:44 PM
Class A output DAC PTSOUNDLAB Digital Source 2 30th April 2003 06:34 AM


New To Site? Need Help?

All times are GMT. The time now is 12:18 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