TDA1541 v/i

[uchu007]

Hello,
Can you explain to me what is this mosfet in the output of the TDA1541 dac on the cd philips?
cordially

 

[Markw4]

It looks like a switch to enable or disable the feedback network immediately to its right that would be in parallel with the network closer to the opamp when enabled. Maybe for de-emphasis?

 

[weissi]

De-emphasis.

 

[uchu007]

Do you think that if I redo this diagram without this part it will work well? Because I try to make a dac from an old CD player, I connect my interface on the input of the TDA1541a and it works very well. I saw that most Philips cd player have this floor cd-94.But now I want to redo a pcb and I took the question on this part, is it essential? Do you have an exit floor diagrams based on aop 5532 because despite my research I can not find much?
I'll close you in advance

 

[MarcelvdG]

For CDs recorded with pre-emphasis (a few of the older CDs have that) sound overly bright when you play them without de-emphasis filter, everything else should sound fine. By the way, judging by its symbol, the FET is a JFET rather than a MOSFET.

 

[lcsaszar]

This is just for Red Book compliance, current CDs don't use pre-emphasis.

 

[uchu007]

Ok ,
thank you for your explanation .
cordially