NFB types

[nironiro]

Hi,
Anybody knows what is the different in those two types of NFB?
What are the advantages of putting NFB ground capacitor in the position A?

I saw that NFB in some cassette decks playback amplifier and wonder why they put capacitor at that position.

Thanks in advance for answers!

 

[U230421]

NFB B is the usual circuit (with a small cap over the feedback resistor), a separate RC series branch controls the hf-feedback better. NFB A is to bypass the large groundcap (with lesser hf bandwidth) so the hf feedback works even better.

 

[nironiro]

Tnx MarsBravo, that sounds reasonable.

There are even more variations of NFB, one Grundig phono preamp have output cap included in the feedback loop.

 

[lcsaszar]

Whatever you include in the feedback loop forward path, its nonlinearity will be reduced by the NFB. Whatever you include in the feedback loop feedback path, its nonlinearity will appear at the output.

 

[MarcelvdG]

There is less signal current flowing through the electrolytic capacitor in case A, so it will distort less (for a given capacitor type).