In position 2 the low frequency response is reduced. There is a 680 ohm
resistor connected across the voice coil and in position 2 a capacitor of
.33 uF is connected in series between the hot ends of the voice coil and the
resistor to make up a high pass filter.
In position 1 the capacitor is short circuited so the low frequency response
is "flat", that is depending only on the response of the microphone
If your voice is dark, you can sort of enhance the highs by using position 2
and increasing the mic gain slightly to obtain normal ALC readings.
PB3SM - SM6CPI