tda 1543 noise in one channel

[figge77]

hi!

as usual im fooling around with a philips cdp. and this one uses tda1543, i have cut the traces from the output and hooked up a op-amp on a separate board according to 1543 datasheet.
this "op board" has its own power and so has the 1543.

bla bla....well i get very high levels of noise in one channel and almost none in the other. why? it aint the op cous its like that even when i hook up directly at de d/a.

the oversampling has been disabled in the player.


cheers

 

[aparatusonitus]

Have you connected grounds from new output board and cd player?

 

[figge77]

well no.

the psu for op is grounded but on the op board there´s just the op and its not. only cables from dac. iref and L/R out...and then axial mkp goes to rca.

oh and the feedback cuircut shown in the tda1543 datasheet.

 

[aparatusonitus]

Then connect opamp ground and TDA1543 ground, +input from opamp is referenced to ground, which in your case seems to floating.

 

[figge77]

maybe a stupid question but how do i ground a 8pin op?

 

[aparatusonitus]

Your opamp is "grounded" via psu (regulated or not), just make shure that you have connected +input to ground as well as TDA1543 ground to opamp ground.

 

[figge77]

thanks!

it works now. i had done it the right way but i had used some crappy cables for ground.
better cables and wow! shure dont sound like the piece of crap cd it is!(CD110) or should i say looks like.

 

[aparatusonitus]

Great! Now enjoy the music and start collecting knowledge about discrete I/V converter for TDA1543 (google for folded cascode I/V) 'cos that's is your next "to do thing"

 

[figge77]

i have been thinking about that. can you point me in some direction? would like it as simple as possible. since i believe more is less. or was it the other way around? hmm

 

[aparatusonitus]

i have been thinking about that. can you point me in some direction? would like it as simple as possible. since i believe more is less. or was it the other way around? hmm

No, it wasn't the other way around...

http://www.diyaudio.com/forums/showthread.php?postid=200327
http://www.diyaudio.com/forums/showthread.php?s=&threadid=23044&highlight=