In article , Floyd Davidson
writes:

"Studio quality AM" is not a valid term. AM Broadcast has never
been up to "Studio Quality" standards, which would be _at_
_least_ 20 to 20K Hz.

Hey, even FM Broadcast is only up to 15 KC. At least that's been the limit
since they added the stereo subcarrier. I agree that recording equipment
should be good at least up to 20 K.


There is no difference at all between the audio response
necessary for SSB and AM. AM, because it has both sidebands,
will necessarily take up twice the RF spectrum for the same
audio response, but in fact 2.4KHz (400Hz to 2800Hz) is actually
*preferable* to higher fidelity audio response when the purpose
is voice communications. (Ma Bell did a bazillion studies on
this decades ago, so it is not exactly new information.)

During my years at Bell Labsm, working in speech coding, our preferred standard
range was 300 - 3300 Hz. At 3300 you have a fighting chance of telling an "F"
from an "S" and a "T" from a "D" sound. At 4000 you have very little trouble.
At 2800 you have all those military types spelling it out with phonetics and
lots of "say again".

The low, bass end doesn't really affect BW much (not at all in AM with
carrier), but too much bass wastes power and voltage swings in the modulator,
and overlaods and distorts in the receiver's audio circuits and speaker, and
also batters your ears. That's why a lot of radios have tone switch
positionsthat cut out some of the bass response. 73, Mike K.




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