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Newbie Question: RCA cable vs. coax connection for DAC

Discussion in 'Digital Sources' started by 70'sMusic, Nov 1, 2018.

  1. 70'sMusic

    70'sMusic Active Member

    Messages:
    176
    Hi Everyone,

    Have a "newbie" question for the collective group's wisdom. I want to connect my CD player to my DAC and I can go "optical" or "coax." Can I use a RCA cable for the "coax" connection?

    Thank you in advance for your help, I really appreciate it!
     

     

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  2. Audioraven

    Audioraven Active Member

    Messages:
    407
    Location:
    Coachella Valley
    If you choose to use an RCA cable for your Coax connection, you need to use one that is labeled for Coaxial Digital use. It should have a 75 Ohm rating if it is designed for Digital hookups.
     
    Bill Ferris, 70'sMusic and yockmyer like this.
  3. dewdude

    dewdude I fix stuff.

    Messages:
    3,060
    Location:
    Manassas, VA
    Yes. It's a coaxial cable so it'll be fine.
     
    Last edited: Nov 2, 2018
    70'sMusic likes this.
  4. 70'sMusic

    70'sMusic Active Member

    Messages:
    176
    Thank you. Do you recommend using an optical cable instead?
     
  5. 70'sMusic

    70'sMusic Active Member

    Messages:
    176
    Cool, thank you!
     
  6. 70'sMusic

    70'sMusic Active Member

    Messages:
    176
    PS:
    The cable I am thinking of using is rated at 110 ohms normal impedance. It's an SVS Soundpath Interconnect.
     

     

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  7. motorstereo

    motorstereo AK Subscriber Subscriber

    Messages:
    10,534
    Location:
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    You should be able to switch back and forth from rca to optical on your dac to see which one sounds better. To my ears the rca was slightly better sounding than the optical. I used a decent quality rca for my initial hookup and later "upgraded" to a 75ohm digital rca. I noticed zero difference in that cable swap.
     
    Last edited: Nov 4, 2018
    70'sMusic and Audioraven like this.
  8. Audioraven

    Audioraven Active Member

    Messages:
    407
    Location:
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    That cable would not be ideal, as it is not designed for use as a digital signal carrier.
     
    70'sMusic likes this.
  9. Audioraven

    Audioraven Active Member

    Messages:
    407
    Location:
    Coachella Valley
    Either type of cable is capable of good performance. Choose the one YOU like the best.
     
    70'sMusic likes this.
  10. dewdude

    dewdude I fix stuff.

    Messages:
    3,060
    Location:
    Manassas, VA
    If you're *that* worried about impedance than you should be using BNC for your interconnects because RCA is not exactly 100% accurate in the impedance department.

    I've also never heard a difference between a proper impedance cable and rigging something up using twisted pair. Maybe over an extremely long run; but most people don't have runs that long.
     
    cpt_paranoia, 70'sMusic and WobblySam like this.
  11. EngineerNate

    EngineerNate AK Subscriber Subscriber

    Messages:
    3,129
    For your average 6' interconnect the difference between cable impedances is unlikely to cause an issue.

    I prefer the coax over the optical when given a choice, except in cases when the source is electrically noisy. Optical was a godsend when using my old laptop as a source as otherwise it injected a ton of noise into the system unless I used a cheater plug.

    Optical tends to have higher jitter than coax on most sources. Whether you can hear that is debatable.
     

     

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  12. 70'sMusic

    70'sMusic Active Member

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    176
    Thank you everyone, I really appreciate the help!
     
    Audioraven likes this.
  13. 70'sMusic

    70'sMusic Active Member

    Messages:
    176
    Just ordered a digital optical cable, will let you know how it goes. Thanks again for the advise, I really appreciate it!
     
    Audioraven likes this.
  14. Tim64

    Tim64 Super Member

    Messages:
    1,183
    Location:
    Southern Oregon
    A little late but with optical from what I have read so don't take it as gospel but shorter the optical cable the less jitter. I have a Sony cd olayer and it only has a optical digital out and it sounds fine to me with a 3 foot cable.
     
  15. lini

    lini just me...

    Messages:
    5,891
    Location:
    Munich, Bavaria
    Main advantage of optical over electrical (alias coaxial) SPDIF is full galvanic isolation by principle. So optical SPDIF is always a good choice, if one would like to avoid possible hum issues. This can for example be interesting, if one would like to integrate a computer into one's audio or AV system, in which that computer would be the only safety class I device...

    Greetings from Munich!

    Manfred / lini
     
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  16. EngineerNate

    EngineerNate AK Subscriber Subscriber

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    Yes, my experience is that for certain computers as sources, optical is a great way to eliminate noise. :)
     

     

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  17. lini

    lini just me...

    Messages:
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    EN: Yup, most regular desktop computers are safety class 1 devices, that require a connection to safety ground. So if one integrates such a computer into one's audio or AV system, which happens to consist of safety class II devices and to be connected to an antenna or cable radio/TV wall socket, chances are pretty high, that this will introduce hum due to different ground potentials, so that one will need to provide galvanic isolation, most usually either with an audio transformer/ground loop isolator between the computer and the audio/AV system or with an antenna ground loop isolator between the wall socket and the system. Both of these approaches may be not entirely non-lossy, though - in which case optical SPDIF can be a welcome alternative - especially if the receiving device isn't an older design, which might still derive its clock from the SPDIF input and thus react less benign to the not rarely somewhat increased jitter (compared to electrical SPDIF) than a modern design, that relies on its own master clock...

    And of course the same would apply, if a CD transport (or CD player, that's merely used as a transport) would happen to be the only safety class I device in a system that otherwise only consists of safety class II devices.

    Greetings from Munich!

    Manfred / lini
     
    EngineerNate likes this.
  18. duncan

    duncan more music than time Subscriber

    Messages:
    88
    Location:
    Ames, Iowa
    To toss my experiences onto the group bonfire: I think all your options are acceptable, but probably you're doing the best thing. Optical cable is reliably good at carrying the 44.1khz data rate that comes from a standard CD player, whereas the advantages of wired coax can come more into play at hi bit-rates like 192khz. And as others have mentioned, there are situations where the optical connection prevents ground-loop / hum / noise issues.
     
    70'sMusic likes this.
  19. 70'sMusic

    70'sMusic Active Member

    Messages:
    176
    Thank you Duncan, I appreciate it!
     
  20. cpt_paranoia

    cpt_paranoia Well-Known Member

    Messages:
    815
    ... and depends on the care taken with recovery of the SPDIF clock at the DAC input. Good clock recovery should significantly reduce the jitter.
     
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