RDH4 says most AM BCB radio makers tried for a final IF bandwidth response of
3.5 kHz
That was in 1955/
Since then, the BW has shrunk in many sets to even less than 2 kHz, especially
in solid
state gear, giving horrid state AM listening.
No good turning up the treble control knob, there is no treble there to boost.


I modified a fairly generic Radio Shack Optimus receiver's AM section by
removing the narrow
bandwidth ceramic filter and using a set of overcoupled IFs in its
place. See:
http://pw2.netcom.com/~wa2ise/radios...tml#solidstate
Sounds a lot better on local stations, though DX will have a lot of
monkey chatter.




The FCC limits interference only partly by bandwidth restrictions. Mostly,
it uses geographic seperation and power restrictions.

By ear, I think most stations go to about 7 or 8 kHz audio. Many of the AM
stations are talkers, but the ads can really sparkle. There's one I hear
which sounds like it goes to the 10 kHz audio max.



Much AM is talkback from mobile telephones, and its pretty dreadful....






Of course talk shows using telephone lines will be limited by the
quality of the phone system.
But you should hear better quality from the talk show host and
commercials played on station
equipment (or via satellite), as mentioned above. Audio from digitally
compressed cell phones sounds the worst.
If someone uses a cell phone to do a remote (like a high school football
game) be sure to
use an old analog cell phone (the kind that one could easedrop on with
an FM scanner radio).
But that assumes that the phone system doesn't do compression at the
cell tower site to send
it down the landlines.