[Elecraft] [K3] Hearing aids, meet K3

[Alan Jump]

As I recall from my broadcasting classes years ago, human speech has a
"typical" bandwidth of just 3KHz. "Normal" human hearing, IIRC, picks up
frequencies from 20Hz to 20KHz.

If someone has a copy of Schrader's "Electronic Communications" ready to
hand, the specifics should be in there somewhere.

 - -
73 de N5ILN
Alan


On Wed, Aug 7, 2013 at 10:33 AM, Jim Brown <jim at audiosystemsgroup.com>wrote:

> On 8/7/2013 8:39 AM, Ron D'Eau Claire wrote:
>
>> So if you enjoy music on your A.M. radio, note that it's unlikely
>> your radio is reproducing much of anything above 5 kHz.
>>
>
> 99.99% of AM broadcast receivers have audio bandwidth of less than 5 kHz.
>  The only ones I know of with bandwidth greater than 9 kHz are the GE Super
> Radio, the Carver TX-11, and a couple of models made by McKay Dymek, and
> all of them are long discontinued.  I have a Carver and several of the GE
> Super Radios. In the early 80s I was selling the McKay Dymek radios to
> broadcasters for use as monitors, and had one at home for a while.
>
> Beginning more than 30 years ago, consumer radios were built to use the
> same detector and audio circuitry for AM that they used for FM, which
> includes 6 dB/octave de-emphasis starting around 1 kHz. This equalizes for
> the pre-emphasis applied at the transmitter, which was, and still is, the
> standard for FM broadcasting. This made AM even muddier than it already
> was, so AM broadcasters adopted the standard of applying pre-emphasis to
> their signals. I don't remember when that was adopted, but I'd guess at
> least 30 years ago. As I recall, that standard also required a low pass
> around 10 kHz.
>
> 73, Jim K9YC
>
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