Le 06/02/2025 à 21:35, Richard Lee via
groups.io a écrit?:
It
sepends on the actual input impedance of the mic preamp.
For
a typical 2kohm input impedance, the capacitor should be
1.15uF for 70Hz cut-off.
The actual response would be first-order, i.e. only
6dB/octave.
Much
less efficient than any active high-pass filter in the
preamp.
The actual effective resistance for LF roll-off is 1k5 (input
Z of the preamp) + Zo (of the mike)? So a much smaller capacitor
is needed for a 70Hz cut-off.
I would say slightly larger.
With Zin= 1.5k and Zo=150r, the capacitor must be 1.35uF for
-3dB@70Hz
?
But Zo of the mike(s) varies a lot so, like Jerry, I wouldn't
use this to set the LF limit but only to get rid of subsonic
noise.
?
Much of this is on page 2 of the latest version of
SimpleP48.pdf? dtd. 29sep24
