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Re: [BCD396XT] Re: 396XT vs RS Amp-Extension Spkr

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  • Lance
    If you short the gnd of the jack to the metal of the sma connector, the internal amp in the radio will produce more audio output... ... [Non-text portions of
    Message 1 of 8 , Oct 10, 2011
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      If you short the gnd of the jack to the metal of the sma connector, the internal amp in the radio will produce more audio output...


      On Oct 10, 2011, at 5:29 PM, Jamie Hanrahan wrote:

      > You should *never* plug a mono phone plug into *any* stereo phone *output* jack. The mono phone plug will short the ring contact in the jack to ground. In an output jack that means you are shorting one of the outputs to ground. It should be obvious why that's not a good idea. (Input jacks are not a problem, though of course only one channel in the jack will be driven.)
      >
      > You should *almost* never plug a stereo-to-monitor adapter into a stereo phone output jack. However the jack on the Uniden may be an exception.
      >
      > The reason the adapter is usually a bad idea: Such an adapter connects both the tip and ring (L and R) contacts in its plug to the tip contact in its own mono jack. When you plug this into a stereo output, the two output channels of the device are now connected to each other, and they are not supposed to be.
      >
      > In almost all audio hookups at all voltage levels, including headphones and headphone jacks, the output drivers are of considerably lower impedance than whatever they're driving.
      >
      > In line level audio, for example, output impedances are 600 ohms at most, sometimes as low as 100 ohms, while input impedance in pretty much standardized at 10K. It is similar for speakers - power amp output impedance is generally a tiny fraction of an ohm, driving a 4 or 8 ohm load. We do not "match impedances" in audio work, unless you're working on long distance analog telephone lines. And the same is true of headphones and headphone outputs; although the impedances of 'phones can vary a lot the driving impedance is always very low.
      >
      > So... when you connect two outputs to the same input you are connecting two low-impedance sources to each other, while also connecting them to the high-impedance load. The result is that the two sources nearly short each other out, as they are each seeing a load that's drawing anywhere from 10 to 100 or more times as much current as they're designed for. Severe clipping is almost always the result. One output may even damage the other output.
      >
      > It is extremely common for people to try this with line level outputs, using a simple "Y" cable to derive a single channel from two. And it is extremely common for them to report that the resulting level is very very low and that it is very distorted. The distortion results from clipping - voltage sag due to the high current loads.
      >
      > (For verification and more details, see the excellent article "Why Not Wye?" at the Rane Audio web site. http://www.rane.com/note109.html , if Yahoo will let me post that link here.)
      >
      > With the Uniden's stereo jack, however, there is a likely exception as these scanners do not decode FM stereo and so have no reason to really have two output amplifier channels. In all likelihood they just have one and it is already connected to both the tip and ring contacts in the jack (for compatibility with stereo headsets). Connecting those contacts to each other (as an adapter would do) therefore does nothing that isn't already being done.
      >
      > --- In BCD396XT@yahoogroups.com, Jeffry Rehm <scanman1958@...> wrote:
      > >
      > > I use a stereo to mono RS adapter for a couple older Uniden scanners that have mono for the earplug connection. However I use it� with a pair of stereo headphones. I really hated hearing transmissions� with only one ear. Not sure if it would or could cause problems with a powered speaker.
      > > �
      > > �
      > >
      > >
      > > --- On Sun, 10/9/11, dataman60435 <dataman60435@...> wrote:
      > >
      > >
      > > From: dataman60435 <dataman60435@...>
      > > Subject: [BCD396XT] 396XT vs RS Amp-Extension Spkr
      > > To: BCD396XT@yahoogroups.com
      > > Date: Sunday, October 9, 2011, 6:50 PM
      > >
      > >
      > >
      > > �
      > >
      > >
      > >
      > > I have a older RS extension spkr that uses 4 "c" batterys or a 9v AC adapter to power it...It has a monaural cable and will not work on the stereo connector on the 396XT....Will a monaural to stereo one eigth adapter do the job or a cable monaural-stereo with out causing damage to the 396XT audio section....Its actually a "Realistic" MPS5, it is vintage but its loud!!...Thank You...
      > >
      > >
      > >
      > >
      > >
      > >
      > >
      > >
      > > [Non-text portions of this message have been removed]
      > >
      >
      >



      [Non-text portions of this message have been removed]
    • Jamie Hanrahan
      The first line there should have read stereo-to-mono adapter .
      Message 2 of 8 , Oct 11, 2011
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        The first line there should have read "stereo-to-mono adapter".

        --- In BCD396XT@yahoogroups.com, "Jamie Hanrahan" <jeh@...> wrote:
        >
        > You should *almost* never plug a stereo-to-monitor adapter into a
        > stereo phone output jack. However the jack on the Uniden may be an
        > exception.
      • Jeffry Rehm
        FYI. I am not pluging a stereo plug (male) into a mono (female) output jack. That is why I am using the adapter specifically designed for that. The stereo
        Message 3 of 8 , Oct 11, 2011
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          FYI. I am not pluging a stereo plug (male) into a mono (female) output jack. That is why I am using the adapter specifically designed for that. The stereo headphone jack plugs into the female end of the adapter (also stereo).  At the other end of the adapter is a mono male plug that plugs into the mono jack of the specific scanner.
           
          I just wasn't sure if there were power issues with the adapter and the powered speaker.


          --- On Mon, 10/10/11, Lance <milcom_chaser@...> wrote:


          From: Lance <milcom_chaser@...>
          Subject: Re: [BCD396XT] Re: 396XT vs RS Amp-Extension Spkr
          To: BCD396XT@yahoogroups.com
          Date: Monday, October 10, 2011, 10:23 PM


          If you short the gnd of the jack to the metal of the sma connector, the internal amp in the radio will produce more audio output...


          On Oct 10, 2011, at 5:29 PM, Jamie Hanrahan wrote:

          > You should *never* plug a mono phone plug into *any* stereo phone *output* jack. The mono phone plug will short the ring contact in the jack to ground. In an output jack that means you are shorting one of the outputs to ground. It should be obvious why that's not a good idea. (Input jacks are not a problem, though of course only one channel in the jack will be driven.)
          >
          > You should *almost* never plug a stereo-to-monitor adapter into a stereo phone output jack. However the jack on the Uniden may be an exception.
          >
          > The reason the adapter is usually a bad idea: Such an adapter connects both the tip and ring (L and R) contacts in its plug to the tip contact in its own mono jack. When you plug this into a stereo output, the two output channels of the device are now connected to each other, and they are not supposed to be.
          >
          > In almost all audio hookups at all voltage levels, including headphones and headphone jacks, the output drivers are of considerably lower impedance than whatever they're driving.
          >
          > In line level audio, for example, output impedances are 600 ohms at most, sometimes as low as 100 ohms, while input impedance in pretty much standardized at 10K. It is similar for speakers - power amp output impedance is generally a tiny fraction of an ohm, driving a 4 or 8 ohm load. We do not "match impedances" in audio work, unless you're working on long distance analog telephone lines. And the same is true of headphones and headphone outputs; although the impedances of 'phones can vary a lot the driving impedance is always very low.
          >
          > So... when you connect two outputs to the same input you are connecting two low-impedance sources to each other, while also connecting them to the high-impedance load. The result is that the two sources nearly short each other out, as they are each seeing a load that's drawing anywhere from 10 to 100 or more times as much current as they're designed for. Severe clipping is almost always the result. One output may even damage the other output.
          >
          > It is extremely common for people to try this with line level outputs, using a simple "Y" cable to derive a single channel from two. And it is extremely common for them to report that the resulting level is very very low and that it is very distorted. The distortion results from clipping - voltage sag due to the high current loads.
          >
          > (For verification and more details, see the excellent article "Why Not Wye?" at the Rane Audio web site. http://www.rane.com/note109.html , if Yahoo will let me post that link here.)
          >
          > With the Uniden's stereo jack, however, there is a likely exception as these scanners do not decode FM stereo and so have no reason to really have two output amplifier channels. In all likelihood they just have one and it is already connected to both the tip and ring contacts in the jack (for compatibility with stereo headsets). Connecting those contacts to each other (as an adapter would do) therefore does nothing that isn't already being done.
          >
          > --- In BCD396XT@yahoogroups.com, Jeffry Rehm <scanman1958@...> wrote:
          > >
          > > I use a stereo to mono RS adapter for a couple older Uniden scanners that have mono for the earplug connection. However I use it with a pair of stereo headphones. I really hated hearing transmissions with only one ear. Not sure if it would or could cause problems with a powered speaker.
          > > Â
          > > Â
          > >
          > >
          > > --- On Sun, 10/9/11, dataman60435 <dataman60435@...> wrote:
          > >
          > >
          > > From: dataman60435 <dataman60435@...>
          > > Subject: [BCD396XT] 396XT vs RS Amp-Extension Spkr
          > > To: BCD396XT@yahoogroups.com
          > > Date: Sunday, October 9, 2011, 6:50 PM
          > >
          > >
          > >
          > >  
          > >
          > >
          > >
          > > I have a older RS extension spkr that uses 4 "c" batterys or a 9v AC adapter to power it...It has a monaural cable and will not work on the stereo connector on the 396XT....Will a monaural to stereo one eigth adapter do the job or a cable monaural-stereo with out causing damage to the 396XT audio section....Its actually a "Realistic" MPS5, it is vintage but its loud!!...Thank You...
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > > [Non-text portions of this message have been removed]
          > >
          >
          >



          [Non-text portions of this message have been removed]



          ------------------------------------

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          [Non-text portions of this message have been removed]
        • dataman60435
          I appeciate all the hard facts on voltage but what can i use to plug in my amplified speaker when it has a one eighth monaural plug into the stereo connector
          Message 4 of 8 , Oct 12, 2011
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            I appeciate all the hard facts on voltage but what can i use to plug in my amplified speaker when it has a one eighth monaural plug into the stereo connector on the 396XT for a little extra volume.....TY

            --- In BCD396XT@yahoogroups.com, "Jamie Hanrahan" <jeh@...> wrote:
            >
            > The first line there should have read "stereo-to-mono adapter".
            >
            > --- In BCD396XT@yahoogroups.com, "Jamie Hanrahan" <jeh@> wrote:
            > >
            > > You should *almost* never plug a stereo-to-monitor adapter into a
            > > stereo phone output jack. However the jack on the Uniden may be an
            > > exception.
            >
          • David Johnson
            Two choices. 1) stereo to mono adaptor. 2) cut mono plug off and replace with stereo plug. Sent from my iPhone
            Message 5 of 8 , Oct 12, 2011
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              Two choices.

              1) stereo to mono adaptor.
              2) cut mono plug off and replace with stereo plug.

              Sent from my iPhone

              On 13/10/2011, at 5:40, "dataman60435" <dataman60435@...> wrote:

              > I appeciate all the hard facts on voltage but what can i use to plug in my amplified speaker when it has a one eighth monaural plug into the stereo connector on the 396XT for a little extra volume.....TY
              >
              > --- In BCD396XT@yahoogroups.com, "Jamie Hanrahan" <jeh@...> wrote:
              >>
              >> The first line there should have read "stereo-to-mono adapter".
              >>
              >> --- In BCD396XT@yahoogroups.com, "Jamie Hanrahan" <jeh@> wrote:
              >>>
              >>> You should *almost* never plug a stereo-to-monitor adapter into a
              >>> stereo phone output jack. However the jack on the Uniden may be an
              >>> exception.
              >>
              >
              >
              >
              >
              > ------------------------------------
              >
              > Yahoo! Groups Links
              >
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              >
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