tda1541a sound signature - Page 2 - 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 9th June 2011, 10:34 PM   #11
diyAudio Member
 
Join Date: Oct 2005
A class-A i can test quickly.
Further i plan to move the opa627 to the buffer and use a ad811 for the I/V, as i saw a circuit from someone who appears to be more knowlegdable than m

As there is also a deemphasize circuit attached to the i/v, it is beyond my capability to cut and paste some discrete stuff.

A better dem-reclocking i save for the last mile, not for the quantumleap i need now.
  Reply With Quote
Old 9th June 2011, 11:19 PM   #12
diyAudio Member
 
Join Date: Oct 2005
Quote:
Originally Posted by jazz View Post
Hi,

I thought there was no dc servo and the cd80 uses a 220uF (c32) cap at the output anyway? Then again I don't care about caps in the signal path.

regards,
Joris
No output-cap, maybe you are mistaken for a philips. c32 is not a part on the list.
  Reply With Quote
Old 10th June 2011, 07:08 PM   #13
jazz is offline jazz  Netherlands
diyAudio Member
 
Join Date: Dec 2001
Location: leiden, physically that is...
Hi,

Yup you are right. Checked the service manual and there is no cap. sorry.

I'd still try the Pass i/v stage though, it's simple and cheap enough to try out. Maybe a good idea anyway, prototyping various i/v stages and see what you like.

regards,
Joris
__________________
oh, what a beautifull day
I wanna go out and play!
  Reply With Quote
Old 10th June 2011, 07:35 PM   #14
GoranB is offline GoranB  Poland
diyAudio Member
 
GoranB's Avatar
 
Join Date: Mar 2010
Location: Poland
I have CD40, with TDA1541 (not A), after i builded separated power supply for 1541 the sound improved a lot. I dont know how its in CD80, but if you have there 7220 and 7310 you can implement a separated PSU for both chips. Decopule the caps on 1541 (if its already not done) with 14 x 220 nF or 470nF.
These modes will result with deep and wide sound stage, natural highs and perfect mids.
  Reply With Quote
Old 12th June 2011, 11:09 AM   #15
diyAudio Member
 
Join Date: Oct 2005
Quote:
Originally Posted by danico View Post
Try to bias the opamp into "class A ".
I use the opa627 just like you do. Put a 2k resistor on pin1 and pin4 (output and -15v).
That will be pin 6 and 4!
  Reply With Quote
Old 12th June 2011, 11:28 AM   #16
danico is offline danico  Hungary
diyAudio Member
 
Join Date: Feb 2010
Location: Hungary
Quote:
Originally Posted by Marcelinho View Post
That will be pin 6 and 4!

Not if you use Browndog adaptor with the 2x opa627.
But yes watch out for the right pins.
output to -V.
  Reply With Quote
Old 12th June 2011, 04:37 PM   #17
diyAudio Member
 
Join Date: Oct 2005
Between the dac and the i/v there is somekind of dc-servo of which i don't understand how it works.
As the i/v process is so important, should i keep it or lose it?
  Reply With Quote
Old 12th June 2011, 05:31 PM   #18
danico is offline danico  Hungary
diyAudio Member
 
Join Date: Feb 2010
Location: Hungary
Quote:
Originally Posted by danico View Post
Not if you use Browndog adaptor with the 2x opa627.
But yes watch out for the right pins.
output to -V.

My bad,sorry. Marcelinho was right about pin2 and pin6 on Marantz cd80.

I should have to check the schematic first.
Attached Images
File Type: png Screenshot.png (140.0 KB, 313 views)

Last edited by danico; 12th June 2011 at 05:36 PM.
  Reply With Quote
Old 12th June 2011, 07:03 PM   #19
diyAudio Member
 
Join Date: Oct 2005
Further investigation suggest that some 2mA is inserted before the i/v stage to negate a always present -2 mA that is present at the output of the dac even when there is no signal.
As long as i work with opamps, I keep that insertion.
For the discrete versions of i/v i don't see much mention of this always present offset, or it's compensation.
  Reply With Quote
Old 13th June 2011, 07:32 AM   #20
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by Marcelinho View Post
Further i plan to move the opa627 to the buffer and use a ad811 for the I/V, as i saw a circuit from someone who appears to be more knowlegdable than m
Beware, you must make significant circuit changes for the AD811 (or LM6181 for that) to work without oscillation.

Another problem could be if you replaced the 5534 Op-Amp's without removing the Frequency compensation capacitors, they may wreak havoc with an OPA627, while pin 8 is marked "no connection", for all we know it may connect to the substrate or something.

Also, the OPA627 is quite slow for I/V. I would recommend using an OPA637 instead and using Scott Wurcers trick circuit (I came up with the same incidentally a long time back) of having a suitable value cap to ground from the inverting input, 10nF in case of the player you have and the OPA637.

As for the "dark sound", also have a look at the DEM Filter capcitors, also, I personally would consider DEM Reclocking and I2S attenuation as essential.

FWIW, the AMR CD-77 uses special PECL based reclocker/drivers for the TDA1541 which among others also perform attenuation, DEM reclocking, passive I/V and ton's of individual regulators, including some tuned to offset the temperature coefficient of the circuit they supply.

The regulators use a wide variety, from current source fed shunts to fully discrete super low noise feedback free ones, each matched precisely to the circuit they supply - there just is no such thing as a "super regulator" that is super in each and every application. They are followed by very carefully selected and designed decoupling and bypassing.

I would say the power supplies account for around 50 - 60% responsible for the final sonic result in the CD-77.

More on the principle design (block diagram) can be seen here:

Abbingdon Music Research - Product - CD - 77 Freatures

A picture of the whole DAC/digital board is found here:

Abbingdon Music Research - CD - 77 Photo Gallery

Over- and/or up-sampling are selectable as well as deflatable. Finally, for PC connections it comes with a USB input (CD Standard only) and in more recent versions also with SPDIF inputs having very low jitter on either input...

A lot of attention has also been paid to the mechanics, which avoid traditional damping and use multiple material sandwiches and application of certain geometric rules to avoid resonant reinforcement of any modes.

So in many areas it is a tour de force of what can be done.

The sound will not please everyone, nor is it meant to, it is a Player that is firmly "Digital to Analog" in sonic nature. Those who actually LIKE digital sound will be disappointed.

Ciao T
  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
FS : TDA1541A & TDA1541A S2 (Double Crown) Pocoyo Swap Meet 2 27th October 2010 04:26 AM
Sound signature differences between IRF510, 520, 530, and 540s? BoilermakerFan Solid State 17 6th August 2010 05:10 AM
MFA Lumi - possible to "un-darken" the sound signature? marknoir Tubes / Valves 16 23rd January 2007 05:02 AM
comments on my signature... roibm The Lounge 90 13th December 2004 08:03 PM
Crackling sound in right channel of TDA1541A DAC HeadSh0T Digital Source 3 9th December 2003 11:16 PM


New To Site? Need Help?

All times are GMT. The time now is 02:11 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