> The manual also doesn't do a very good job of explaining the BP/Fade
> control either. The way I understand these knobs, they are some
>sort of audio passband tuning; is this correct?
Yeah. Think of it this way. First there is a very sharp BPF which has
a tunable center frequency. With the fade control you can select from
only the output of this filter continuously to only the unfiltered
signal. The aural effect is a filter with continuously variable skirt
selectivity - from very narrow to full wide.