AM wide 12-16khz
Am narrow 6-10khz

Maybe it's my aging male ears but I've never heard an AM transmission
where a 10kHz filter was needed or even desirable. Whenever I switch
on the wider filter I just hear more hiss and static, and no more
fidelity.

I can hear a small difference between 6kHz, 8kHz, and 10kHz with local
AM BCB stations. My preference has always been to abhor hiss so I tend
to go towards the narrower side. I don't think my ears are as
sensitive to hiss as when I was younger but it still bothers me
especially with extended listening.

I am told that the 16kc wide filter on my R-390A was used largely for
when multiple channels were being multiplexed (e.g. multi-RTTY or
multi-voice channels).

Tim.