[BC] AM Stereo

[Barry Mishkind]

At 11:59 AM 11/25/2010, Jerry Mathis wrote:
>The problem is, the receiver manufacturers NEVER CAME THROUGH with their side of the bargain. They continue TO THIS DAY to make crappy AM radios with an audio frequency cutoff somewhere down around 3 kHz now. I don't even try to listen to AM anymore. Unless you've got REALLY GOOD audio processing, everyone talking on AM sounds like they have their hand over their mouth. My degraded hearing accounts for SOME of that, but not all.

        I really hate to re-enter this discussion, but since it is
        wandering and we are now shouting..... 

        1. The manufacturers have done only what they needed
        to do to prevent millions of cars being returned for
        having "defective" radios. Argue all you want. Their
        goal is not to have "the best audio" .. it is to have the
        least service requests.

        2. The broadcast industry shot itself in the foot on this
        one. The relentless Modulation Wars and pre-emphasis
        hyping caused so much inter-channel chatter that the
        only defense was to reduce the bandwidth. 

        3. If broadcasters had not been so fixated on 99.9%
        negative modulation, the Magnavox AM Stereo system
        (the topic of this thread) would have worked just fine.
        
        In fact, I would think that the true experts on this list,
        like Bob Orban or Greg Ogonowski (the others are 
        lurking - we haven't seen much from them in a while)
        would suggest   that anything over 92% negative probably 
        causes more distortion than loudness. 

        4. Without the NRSC "truce" (a little better than the
        Korean War truce ...) the escalating pre-emphasis
        would have brought AM bandwidth down to almost
        nothing.

        With the NRSC "truce" we have a sort of "status quo."
        The existing pre-emphasis curve and the car bandwidths
        are about as good as can be expected.

        5. It isn't possible broadcasters could "back off" a bit now
        to tempt the manufacturers to "open up" ... the proliferation
        of signals on the AM band - including the high power,
        hyperdirectionals with their off-carrier sidebands - has
        been as detrimental to AM reception as the increasing 
        man-made RFI.

        Really, between the industry wars and the timid FCC, it is
        broadcasters themselves - the same bunch who 
        decided to automate stations to save money - who 
        have really made the mess. 
        

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