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how to ad digital coax out to cd player without it?

Discussion in 'DIY' started by ferninando, Jun 17, 2017 at 2:25 PM.

  1. ferninando

    ferninando AK Subscriber Subscriber

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    hope some of you DIYrs can help me.
    I need to know what to do to ad a digital coax out put
    tp one of my cd players that does not now have one
    so I can use an external DAC with digi coax input.
    anyone want to tackle this?
    any info is appreciated
     
  2. luvvinvinyl

    luvvinvinyl Admin Staff Member Admin Subscriber

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    I can't help you, but those who might probably need to know what deck is under discussion.
     
  3. Alan0354

    Alan0354 Super Member

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    Buy a new CD player with digital out. You need to convert from analog to digital, the quality all depends on the converter even if you have a perfect CD player. You don't want to go into the internal of the CD player to do that, that's likely to be way way way too complicated if even possible.
     
    BMWCCA, techguy0192 and Hyperion like this.
  4. ferninando

    ferninando AK Subscriber Subscriber

    Messages:
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    there are some how can do it no prob. just have to know where to tie in to. .
    dont need more new cdps.
    need to add coax digital output to existing cdp that does not have one..
    I want to be able to use an external DAC, of which I have 2 and getting another.
    thanks for the reply .

    PS: one CDP is a sony and one is a pioneer
     
  5. petehall347

    petehall347 the brandy coffee man Subscriber

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    be a good idea to study schematics of one that does have coax out .
     
  6. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    This is a non - trivial procedure. There was an article on how to do this years ago in Audio Amateur. You have to add additional circuits.
     
  7. ferninando

    ferninando AK Subscriber Subscriber

    Messages:
    12,213
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    will do , thanks
     
  8. Bob

    Bob AK Subscriber Subscriber

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    in general, you tap the digital output of the digital signal processor (DSP) - at the junction
    where it meets the internal DAC.

    look at Harman Kardon hd7500/7600, one has only RCA analog outputs, and the other
    has both analog and digital outputs. there's added circuitry for this.
     
  9. ferninando

    ferninando AK Subscriber Subscriber

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    thanks for that Bob. I'll chk it out
     
  10. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    As I recall, in the article they said you have to reclock the data. Also you may need to add a buffer because the DSP probably isn't meant to drive the capacitance of a cable.
     
  11. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    You can make a huge improvement in the sound by replacing the opamps in the filter and final stage of the CD player. The internal DAC is usally very good, but the opamps garbage up the sound. Sony used lousy opamps in their players. You can replace them with a drop in replacement; LM4562 and the sound will rival a high end player. This is usually the reason for lackluster sound in CD players.
     
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  12. Bob

    Bob AK Subscriber Subscriber

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    dr*audio is absolutely correct. and this is the easiest way.

    alternatively, if you are really serious about this, read all 700+ pages at diyaudio on digital sources
    you'll get everything on I/V conversions, reclocking, adding DACs, oversampling, etc.

    AK is great for specific information on a given CDP. and of course, the great tips on fixing CDP
    from dr*audio.

    I have two CDPs from the golden age that have implemented DACs using discrete components
    and will probably do the same as you - time and energy permitting.
     
  13. ferninando

    ferninando AK Subscriber Subscriber

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    I am going to put the LM4562s in my sony 302, the one with no digital coax output..
    Just to see what happens, using sockets for kwik change.
    BUT, Due to the incredible complexity of the circuits, that without a PHDEE degree, it appears
    that installing a digital coax out is a futile exercize and I dont think I will persue it any further.
    Unless someone can give me all the technical info needed to do it. More web searching .
    That HK 7600 is a true nitemare.

    PS: I will look more at diyaudio for sure.

    thanks to all for the info.
     
    Last edited: Jun 18, 2017 at 9:35 AM
  14. Bob

    Bob AK Subscriber Subscriber

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    there were kits that you "attach" to your CDP main board. some came as parts and some
    came as finished boards.

    how is the HK 7600 a nightmare. there are two places where they attach a transformer
    and another where there's a circuit for both types of digital outputs. don't let the parts
    count deter you - you're not touching the rest of the circuit only tapping the DSP output.

    compare the 7500 (no digital outputs) and the 7600 with digital outputs. It doesn't get
    simpler than what I described above - two parts with maybe a dozen solder points
    including most of the hard work in punching through the back panel and adding
    connectors and labels.
     
  15. ferninando

    ferninando AK Subscriber Subscriber

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    Bob, I really apppreciate your encouragement.
    I am gonna let it go for now and maybe wait and see what someone has actually done that works
    without any problems.
    I appreciate everyones info. thanks.
     
  16. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    On the CDP-302, also tighten the screws that secure the pc board. Sony used those screws to complete the ground path. They get loose over time and the sound degrades. Highs sound mushy.
     
  17. BMWCCA

    BMWCCA AK Subscriber Subscriber

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    Cheaper and better, and won't ruin the CD-player you love that you want to mod. :dunno:
     
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  18. ferninando

    ferninando AK Subscriber Subscriber

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    but even new ones do not always provide digital outputs.
    and I know to look for them when shopping and never get one without.
     
  19. Bob

    Bob AK Subscriber Subscriber

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    and then there's the models that play both CD and SACD, CDs output both the digital and
    the analog, but the SACD comes only through the analog which you means you are
    chained to the quality of the built-in DAC. the good news is that the DAC was chosen to
    support the DSD (and who knows what DSD to LPCM to analog conversions along the way)
    and CD was dragged along.
     

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