Other ways to make the high pass slope very gentle

See also the Pleiades L in series with R microphone filters.


Another way can be for example:


Using a JFET or electron tube in a circuit such as Pleiades V6. But with a source resistor bypassed by a capacitor of low value. So the very low bass is not amplified.


Or using a resistor in series to the bypass capacitor etc.


Such elegant slope changing techniques may be seen on FBT electron tube PA mixers, the Altec electron tube preamplifiers etc.