TDA1541 "Fizz" - 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 30th March 2004, 11:01 PM   #1
nwilson is offline nwilson  Ireland
diyAudio Member
 
Join Date: Mar 2004
Location: Blarney
Default TDA1541 "Fizz"

Gentlemen, I have a problem!

I have just built a DAC comprising a CS 8412 and a TDA1541A in what I suppose is the datasheet configuration.

It works, but there is a background “fizz” sound. It is pretty low-level, but I’m not talking about some sort of audiophile “Golden Ears” effect. It is pretty obvious!

OK. I know you need some information -

About the sound:

The sound is not a buzz from the power supply – I know what a 100Hz ripple sounds like!

It is not “hiss”. I really think “fizz” is the best description. It is modulated by the programme material. It is at its most obvious during low level – but not silent - material.

I wonder if it might be quantization noise. Could I have a few of the lower bits sticking?

About the circuit:

It really is datasheet stuff -

It is built on “Vero” and the earthing strategy is a bit schoolboy, but I expected that it would work and that multiple regulators, star grounding etc would yield “audiophile benefits”?

I know it’s not a lot to go on, but does anyone recognise the symptoms?

Nick
  Reply With Quote
Old 31st March 2004, 11:25 AM   #2
diyAudio Member
 
Join Date: Oct 2001
Location: Sweden
Send a message via MSN to Flemming J P
My old dac boards where also done on vero boards with local regulators (lm317/337) and stargrounding and also had some problems.

In my dac it sounded like fast morsecode at very low level with a hich pitch tone 1k-3khz.

Never found out what it was. My current dac boards using the same 1541 doesn't have this problem.

So it must have been something stupid I did or didn't do.
  Reply With Quote
Old 31st March 2004, 11:39 AM   #3
Zodiac is offline Zodiac  United States
diyAudio Member
 
Join Date: Jun 2003
Location: Kenfield, CA, USA
Default Grounding



Sounds like a grounding issue to me. Could you explain your ground layout, or better draw a picture?

I've had these problems before, ranging from midly annoying (like your problem) through to big crackles through the speakers (due to long ground paths and sharing of signal with power grounds)

  Reply With Quote
Old 31st March 2004, 02:53 PM   #4
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Could be a bad DAC chip......

Heat it up with your heat gun, then blast it with some freeze spray. If it stops at that point, then it is on its last legs.


Jocko
  Reply With Quote
Old 1st April 2004, 06:31 AM   #5
nwilson is offline nwilson  Ireland
diyAudio Member
 
Join Date: Mar 2004
Location: Blarney
Hi

Zodiac was spot-on. I broke a couple of loops in the grounds and the background noise went away.

Now I want to improve the grounding further but I don't know whether the 3 power supplies for the DAC IC should be decoupled to the analog or the digital ground.

My guess is that the + and - 5 are digital and that the -15 is analog - does anyone know??

Nick
  Reply With Quote
Old 1st April 2004, 10:02 AM   #6
guido is offline guido  Netherlands
diyAudio Member
 
guido's Avatar
 
Join Date: Mar 2002
Location: diepe zuiden
Hi,

When you look at some design on the nets, you can find +5 and -5 are digital and -15 is analog. That's were i got the info.

Best layout as far as i know:

+5 and -5 decoupled to dgnd (obvious)
-15 to agnd (also obvious)
DEM caps to agnd (can also be found on the net)

Connect dgnd and agnd with a trace under the DAC as short as possible.

Use a starground on the agnd pin (PS, outputs, DEM caps, trace to dgnd)

Use a groundplane for dgnd. Then use a separate PS for digital and analog supply (2 transformers), so there is no groundloop.

I am using this setup without problems. Comments

Greetings,
__________________
GuidoB
  Reply With Quote
Old 1st April 2004, 10:14 AM   #7
Bricolo is offline Bricolo  France
diyAudio Member
 
Bricolo's Avatar
 
Join Date: Nov 2002
Location: Grenoble, FR
The other Guido won't be happy with your grounding scheme
  Reply With Quote
Old 1st April 2004, 02:32 PM   #8
guido is offline guido  Netherlands
diyAudio Member
 
guido's Avatar
 
Join Date: Mar 2002
Location: diepe zuiden
Mmm,

Think i discussed it with him in some post here. He was not unhappy with it iirc.

What is wrong in your opinion?

GuidoB
__________________
GuidoB
  Reply With Quote
Old 1st April 2004, 02:36 PM   #9
Bricolo is offline Bricolo  France
diyAudio Member
 
Bricolo's Avatar
 
Join Date: Nov 2002
Location: Grenoble, FR
Nothing is wrong, IMO. But things can be improved.

I had a discussion with Thorsten on this subject, not so long ago on this forum (less than 1 month). Look for the thread, he explained it better that I could
  Reply With Quote
Old 1st April 2004, 03:05 PM   #10
guido is offline guido  Netherlands
diyAudio Member
 
guido's Avatar
 
Join Date: Mar 2002
Location: diepe zuiden
Quote:
Originally posted by Bricolo
Nothing is wrong, IMO. But things can be improved.

I had a discussion with Thorsten on this subject, not so long ago on this forum (less than 1 month). Look for the thread, he explained it better that I could
Have a look here http://www.diyaudio.com/forums/showt...5563#post95563

and shoot away.

You can see two tda's on the right and the grounding.

GuidoB
__________________
GuidoB
  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
What makes an amplifier "bright", "warm", or "neutral"? JohnS Solid State 51 13th December 2009 06:42 PM
What makes Nichicon "muse"/"for audio" caps different ? percy Parts 2 3rd October 2009 05:53 PM
Some final pics of "Stacks" revisited and "Askew" with stand Andy G Multi-Way 2 3rd February 2005 06:07 AM
Anyone used Scan-Speak's "Flow Resistors" or "Aperiodic Vents"? Ignite Multi-Way 3 18th November 2001 08:42 AM


New To Site? Need Help?

All times are GMT. The time now is 07:44 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