Who says Am sound Sucks? You can now add Am Stereo to Your Tuner

Discussion in 'Tuners' started by Audioo, May 25, 2018.

  1. vwestlife

    vwestlife Well-Known Member

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    712
    It depends. Many tuners run the AM audio through the same 75 ┬ÁS de-emphasis as FM, causing a loss of treble response. In this case, installing the C-Quam decoder, and thus bypassing that audio filtering, can improve the AM audio quality quite a bit, even if no stations in your area are broadcasting in AM Stereo.

    For the pedantic: Yes, AM stations do use a pre-emphasis curve, but it's not as extreme as FM's -- it tops out at 10 dB at 10 kHz, instead of 17 dB at 15 kHz. Thus, even with a wideband detector, running the AM audio through FM de-emphasis will still result in it sounding dull.
     
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  2. hjames

    hjames dancing madly backwards ... Staff Member Moderator Subscriber

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    Its still Bandwidth limited AM with limited stations available, primarily TALK.

    Like having a very well appointed bespoke YUGO - but - its still a Yugo ...
     
    Last edited: May 31, 2018
  3. spicer

    spicer Super Member

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    General Motors offered AM stereo on several of their car lines back in the eighties, Cadillac for sure... I acquired one, replaced the cassette belts, and put it in my Olds Cutlass real wheel drive. I never actually used it, kind of novelty, used the cassette, but there were a number of Southern California AM stations broadcasting in stereo and it definitely had more fidelity than regular AM. I forget now but the technology made use of both the upper and lower part of the carrier which effectively doubled the bandwidth and increased the frequency response to 10K, which is a great improvement. As an aside, that GM unit was a performer... had music search, auto reverse utilizing a four channel head, five band equalizer, frequency derived motor speed control, four bridged output amplifier stages, switchable dynamic noise elimination... a well designed unit with excellent build quality.
     
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  4. gadget73

    gadget73 junk junkie Subscriber

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    The original stereo in my 1991 Lincoln Mark VII was AM stereo. Found it out one night when band surfing and noticed the ST indicator pop on. It was a talk station, which made no sense to broadcast in stereo.
     
  5. comish4

    comish4 comish4

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    For those of you asking about Cleveland try 1450 WLEC out of Sandusky nice easy music Rock on that AM dial.
     
  6. Audioo

    Audioo Active Member

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    They have a new and improved one that came out recently
     

     

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  7. Audioo

    Audioo Active Member

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    Item no longer available
     
  8. bobschneider

    bobschneider AK Subscriber Subscriber

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    The one they show at http://meduci.com/better_radios.html is the one I have. However, I don't see any information about how to purchase, either on their site or the auction site. They do sell the converter board on the auction site, as well as on their own site.
     
  9. vwestlife

    vwestlife Well-Known Member

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    712
  10. Punker X

    Punker X Moderator Moderator Subscriber

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    Nope, but thank god..
     
  11. KentTeffeteller

    KentTeffeteller Gimpus Stereophilus!

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    In my area, we have an oldies station, a classic rock, and a big regional 50 KW oldies station on AM, and there's a classic country or three near my other home. All of these run excellent audio and among the best AM can give.
     
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  12. dewdude

    dewdude I fix stuff.

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    Stereo itself isn't going to increase the fidelity. The main reason a LOT of AM-Stereo radios and stations..the vintage ones at least...sounded better was the fact the AM stereo radios typically had a super wide IF. FCC specifications allow an AM station to have a REALLY wide bandwidth; the emission standards don't specify any attenuation until 10khz out from the carrier; this means the first 10khz of the signal requires no special handling. From there, there are sideband requirements...but that doesn't mean a station couldn't broadcast a 30khz wide signal...they just have to make sure sideband emissions are so many dB below the carrier after 10khz. (Remember, AM has sidebands on each side of the carrier, so a 10khz wide audio signal would use 20khz of RF spectrum.)

    Some AM stations use the entire 10khz of audio...some actually don't. HDRadio is actually making it difficult due to the fact it widens a stations channel and some stations are actually having to narrow bandwidth to avoid interference.

    But the biggest factor is no one makes an AM radio with a 20khz IF...and a lot of "wide" tuners I've heard aren't MUCH wider. They're a far cry from hearing something at it's full width.

    https://dewdude.ath.cx/wkcw.mp3 is a recording I made of the local 22kW (daytime) classic hits station on 1420. I did this using one of those super cheap RTL-SDR dongles with a frequency upconverter a couple years ago. Yes, it's noisy because the RTL platform was NOT designed to be picking up AM radio...let alone anything other than digital UHF tv; this was also just a lousy piece of longwire for an antenna. But since all demodulation is done in software....I could easily set the bandwidth to the full 20khz.

    HDRadio causes some serious incompatibilities with CQuam...mostly because CQuam uses phase modulation in addition to amplitude modulation. The phase modulation can apparently screw up the HDRadio sidebands...back when HDRadio was forbidden at night...most of the systems transmitted a CQuam compatible signal as the HDradio chipsets are *somewhat* CQuam compatible.

    AM is on it's way out. It's a sad fact, but it's true. The revitalization efforts do nothing to solve the problem long-term and, instead, just start letting everyone pump out more power. Systems like HDRadio make it difficult to listen to analog systems...and the expense of and "failure" of HDradio means no one wants to support it. But I'll also point out the only people using HDradio these days are "the big broadcasters"...most of which are billions in debt and either bankrupt, restructuring, or dragging the process out. Remember, as much as HDradio raises the prices on a receiver; stations have to pay a yearly license fee to iBiquity for the privilege of using it. ARound here...pretty much all of the small stations that ran it for a while stopped...it was too expensive with no payback. No one wants to invest in a new radio with smartphones.

    What we really need is a new radio system built from the ground up to be digital and using all open standards. It has worked fantastically in other countries. I have no clue why we're holding on to this outdated and severly limited idea.
     
  13. hjames

    hjames dancing madly backwards ... Staff Member Moderator Subscriber

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    I thought HD radio was a service used on FM stations?
    ... that seems to be what we have here in the DC area.


    Or, more likely, I am just WAYYY out of touch on AM channels ...


    Felix Grant - jazz at night on WMAL- 630 AM - was a biggie for me.
    After he went off the air (and has since died), there wasn't much musically there for me -
    and we had so many FM choices for a number of years ...
     
  14. dewdude

    dewdude I fix stuff.

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    Location:
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    From the very start, HDRadio was built for both AM and FM service. That was the big thing when they brought it out. There were apparently a large number of problems once they implemented it, so the adoption on the AM side was slow.

    But you're correct, none of the AM stations in the DC area..at least as of last year, were running HDRadio on AM. I think the only "big" AM stations we have around here are WMAL and maybe the sports channels. The rest of the stations aren't "important" enough to warrant the expense and hassle of an HD AM....and WMAL already has an FM feed. Pretty much the only stations in the DC area running HD are WAMU, WTOP, 106.7, and anything owned by iheartbankrupt----I mean iheartmedia.
     
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  15. RxDx

    RxDx Speaker collector Subscriber

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    As I understand it, the equipment for AM HD isn't even being manufactured any more.
    Stations run it until something breaks...

    There's still a land-rush around new AM licenses, if only to enable translators on FM,
    so the band isn't going away any time soon. But a digital switch-over isn't going to
    happen. No one buys table-top radios.
     
  16. dewdude

    dewdude I fix stuff.

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    How does a table-top radio have anything to do with a digital switchover. Are you trying to say table-top radios are the only radios out there? ARe you trying to say a digital switchover wouldn't occur in cars or portable devices?

    Most people don't even buy radios anymore. Most people don't even use the flippin radio anymore. Both are on their way out in my opinion...AM just before FM. A lot of the new licenses are being issued hastily...and aren't doing anything to help the band. More stations does not mean new life...it just means more garbage you may not be able to hear over the other 15 new licenses on adjacent channels.

    But saying a digital switchover isn't going to happen because no one buys table-top radios isn't right. Take a look at other countries....the opposite has happened and full digital has completely taken over.

    It would provide more bandwidth for stations and could actually reduce the burden on the broadcaster if the system is engineered right.
     

     

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  17. EngineerNate

    EngineerNate AK Subscriber Subscriber

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    I feel like it's only a matter of time before the spectrum currently used for radio is repurposed to expand the current wireless data networks. In most areas it already makes way more sense to simply stream live over the internet than bother with setting up a radio station if you don't have legacy hardware and license rights.

    Phones are your average person's primary media consumption device, and it's been probably a decade since a phone with a novelty FM radio feature was released. FM and AM are both dying and stations that can't transition to an internet based business model will likely soon vanish.
     
  18. RxDx

    RxDx Speaker collector Subscriber

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    If no one is buying radios, why would station owners risk what audience they have by
    making current hardware obsolete?

    All-digital changeover in other countries is only happening on FM, AFAICT.
     
  19. amptramp

    amptramp Active Member

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    Location:
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    A lot of people only use radio in the car. I don't think internet radio is going to get any entry into the automotive world because this would mean free internet coverage over large areas. The biggest competitor to radio is stored music. Why use the radio and get programming that is probably not to my taste when I can switch to the CD player and get sound I like enough to have bought it? The big market for radio is breaking new music onto the scene but the top 40 format gives away this advantage.
     
  20. EngineerNate

    EngineerNate AK Subscriber Subscriber

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    I don't know anyone my age who uses the radio frequently. Even in the car my generation and below tends to connect their phone to the sound system, whether by aux in, Bluetooth, tape adaptor, Car Ply, Android Auto... With many carriers not charging for data for streaming services or offering unlimited plans once again it's almost a mathematical certainty that services like Spotify will kill radio at some point. The world is moving to an "always connected" society whether the cell carriers like it or not.

    I wouldn't be surprised if cars stopped offering FM radio if it weren't for the fact that it's used for emergency broadcasts. My grandfather returned a Lexus he bought and got an Acura because the FM radio that he listens to constantly was such an afterthought in that car that the reception was garbage even after repeated trips to the dealer for adjustments/part replacements/tweaking.
     

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