'74 Duster Radio

Discussion in 'Mopar Interiors' started by Dan_the_Mopar_Man, May 16, 2018 at 9:06 PM.

  1. Dan_the_Mopar_Man

    Dan_the_Mopar_Man New Member

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    Gotta question, I knew this stuff 38 years ago when I was doing this stuff all the time, but age caught up and I just don't remember anymore lol. My dash speaker is not working, so I want to wire a pair of speakers I put up in the back window to the factory am/fm radio. I know it won't be stereo, just two speakers instead of of one. There's a green and a black coming out of the radio. The speakers have two leads, the green and green/black and the grey and grey/black, (left and right). What goes where? Also, I want to wire my old under the dash cassette player in there too. It's got four wires, a red power, black ground, and a green and a grey. Can I wire this with it going to the same speakers along with the factory radio? Any help appreciated. Everything I find online is modern harnesses...
     
    Last edited: May 16, 2018 at 9:15 PM
  2. Steven190

    Steven190 FABO Gold Member FABO Gold Member

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    I do not have a 74 , but will try to help.
    The black wire and the one with the stripe is usually the ground. So my guess is that the green out of the radio will go to the speakers. So the gray and green are connected to the green out of the radio, and the blacks are connected together.

    Good luck
     
  3. halfafish

    halfafish 66 Valiant, hot-rod in training FABO Gold Member

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    The best solution would be to replace the dash speaker. The radio is mono, designed to power just one speaker. The green should be + to the speaker, the black should be ground.

    The two speakers in the back will normally be wired green (left+) and green/black (left -) with the other side being grey (right+) and grey/black (right -). It's not a good idea to run two speakers from an old unit designed to run just one speaker, no matter how you wire them (series or parallel) you will most likely be changing the impedance load which is no good for the radio's amp. Adding the cassette player is the same deal.

    If it was me, and I really wanted to use the two speakers in the back, I'd just replace the radio with one designed for two speakers.
     
  4. Steven190

    Steven190 FABO Gold Member FABO Gold Member

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    halhafish is on the right track, the radio most likely will not work well for your application.
     
  5. superchargeddrt

    superchargeddrt Well-Known Member

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    If you connect both speakers to your radio you will not have the correct impedance. Your factory radio wants 8 ohms of impedance connecting 2 of them to your radio will result in an impedance of 4 ohms. The radio will not sound as good and it will be hard on the output transistor and may cause it to fail. If you connect it to only one of the two speakers then you might be okay. The reason I say might is because the connections to the cassette player also being on the speaker might also effect the impedance.
     
  6. Dan_the_Mopar_Man

    Dan_the_Mopar_Man New Member

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    I don't know if I can get up there where that speaker is. I wonder if it might be easier to get at if I pulled the instrument cluster?
     
  7. 73hcode

    73hcode Well-Known Member

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    Ok let me ask a question also about the radio my 73 D/S has a factory am radio but also a factory rear speaker were there different radios? My fender tag says R11. Just curious on the impedance thing.
     
  8. Dan_the_Mopar_Man

    Dan_the_Mopar_Man New Member

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    My Duster originally had an AM, I have the R11 fender tag code too, but I am changing it to an original factory am/fm, not sure of the year, but it's the right radio, same size, same knobs, looks exactly like the one I had in my old '73. My car doesn't have a factory rear speaker, and both radios only have the single speakers wire coming out, black and green.
    I decided to go a different route now though, I am sending it out to be refurbished and upgraded to 4 channel stereo/bluetooth/aux. I'll have an original radio but with all the capabilities.
     
  9. 73hcode

    73hcode Well-Known Member

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    Yes I get what you are saying I was just wondering about from the factory were radios selected by the number of speakers in the car meaning were the ohms changed at the factory for the two speaker cars. It would kinda override the talk of the impedance issue I think. Just playing devil’s advocate. Lol
     
  10. superchargeddrt

    superchargeddrt Well-Known Member

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    The difference is that the output goes to a fader control and it's engineered to keep a 8 ohms impedance on the output transistor. By the way I used to repair car radios and I would find a lot of fried output transistors.
     
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