In article ,
Arny Krueger wrote:
"Paul Stamler" wrote in message

Yeah, but if you're designing the thing yourself you can do it so as
not to need 100uF. Make the resistance on the right-hand side of the
cap 10k and you can get away with 10uF. That's doable in
polypropylene.

It's not free. The reactance of the cap at low frequencies adds to the
impedance seen by the amplifier, and low frequency noise increases
accordingly.

Yes, but it's low frequency noise, and only that component caused by
the front end's input current noise, so it's really pretty benign.
Sure, it's nice to not have it there at all, but using 10uF isn't such
a horrible compromise. 10uF has a reactance of 150 ohms at 106Hz, and
that's not all that high up there. Use 20uF and you move the turnover
to 50Hz, which is probably lower than the 1/f noise from most
semiconductors used in front ends anyway.


Regards,

Monte McGuire