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Thread: XLR to RCA

  1. #1
    Join Date: Mar 2017

    Location: West Sūžsēaxe

    Posts: 1,989
    I'm Edward.

    Default XLR to RCA

    Is there anything I should be aware of by going from XLR to RCA?

    Of course I know I will lose balanced common mode rejection advantages but curious if there is anything else I should be aware of.

    I see XLR to RCA cables being sold from a few pounds to many hundreds. I don't get what advantages there are for buying a 'high end' cable instead of a cable that is well made with shielding.

    Are there any significant voltage issues by going balanced to single ended?

    I will need a cable in a short while to connect a DAC (which has XLR balanced outputs) to a RTR which only has RCA inputs. I'm already using the DAC's RCA output. The pre I'm using does not have tape outs - hence needing to take the signal from the source.

    cheers
    E
    Current: [P20] Roon/Tidal > Custom PC> Metrum Hex > Phast Pre > Neuro. 686 > Tannoy Berkley (RFC tweaks)


  2. #2
    Join Date: Jan 2009

    Location: Essex

    Posts: 27,568
    I'm openingabottleofwine.

    Default

    Most balanced line cables terminated in an XLR connector at one end and an RCA at the other, short out the -ve going signal by connecting the wire that would have gone to pin 3 to pin 1 along with the shielding.

    Check to make sure your DAC won't suffer any damage by having one half of its output shorted to ground. Usually most items having a balanced output will be OK, as often there is a series resistor fitted to the ouput leads within the equipment.

    Typically a balanced output will be 2V pk-pk, whereas most RCA inputs ony require 0.5 - 1.0V for full operation.
    Barry

  3. #3
    Join Date: Mar 2017

    Location: West Sūžsēaxe

    Posts: 1,989
    I'm Edward.

    Default

    Quote Originally Posted by Barry View Post
    Most balanced line cables terminated in an XLR connector at one end and an RCA at the other, short out the -ve going signal by connecting the wire that would have gone to pin 3 to pin 1 along with the shielding.

    Check to make sure your DAC won't suffer any damage by having one half of its output shorted to ground. Usually most items having a balanced output will be OK, as often there is a series resistor fitted to the ouput leads within the equipment.

    Typically a balanced output will be 2V pk-pk, whereas most RCA inputs ony require 0.5 - 1.0V for full operation.
    Cheers Barry

    The DAC is a Metrum HEX, but I don't have a manual for it and can't see one online. How would I check if a protective resistor is fitting? Can I simply open it up and look behind the xlr outputs?

    Thanks for the voltage info. In an XLR to RCA cable would the voltage still be 2v peak? I don't want to run the risk of overloading the RTR input board. Of course I would anyway use the RTR input pot.

    An alternative for what I'm trying to achieve is to use a Y splitter from the DAC's RCA output. Do you see any issues doing this? Impedance?

    More generally do you have any other ideas on doing what I'm trying to achieve (recording source but without a rec/tape out on the pre)?

    cheers
    Current: [P20] Roon/Tidal > Custom PC> Metrum Hex > Phast Pre > Neuro. 686 > Tannoy Berkley (RFC tweaks)


  4. #4
    Join Date: Jan 2009

    Location: Essex

    Posts: 27,568
    I'm openingabottleofwine.

    Default

    Sorry I can't tell you if your Metrum HEX Dac will be OK to have one half of the DAC shorted to earth. I can only find limited information on how the single ended (i.e. the RCA) outputs are derived from the balanced outputs. Metrum use a pair of Lundahl LL1527XL transformers to do this.

    Looking at the specification sheet for the LL1527X http://www.lundahl.se/wp-content/upl...s/1527_7xl.pdf, the transformer can either output the same voltage as the balanced output, or one half of the balanced output. I would expect the unbalanced output to be one half that of the fully balanced output.

    And since the source impedance is low, it would be possible to split the single ended output between your preamp and your RTR recorder, provided of course they both have a high input impedance (say 10K or higher).

    What preamp are you using and what is the RTR?
    Barry

  5. #5
    Join Date: Mar 2017

    Location: West Sūžsēaxe

    Posts: 1,989
    I'm Edward.

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    It is a Phast pre. The decks are a Revox B77 and an Akai gx620.

    All just fun projects.

    The decks are currently being serviced (caps etc).

    §
    Current: [P20] Roon/Tidal > Custom PC> Metrum Hex > Phast Pre > Neuro. 686 > Tannoy Berkley (RFC tweaks)


  6. #6
    Join Date: Jan 2009

    Location: Essex

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    I'm openingabottleofwine.

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    Both the Phast pre and the Revox B77 have sufficiently high input impedances (100K and 220K respectively) for you to drive both using a Y- splitter.
    Barry

  7. #7
    Join Date: Mar 2017

    Location: West Sūžsēaxe

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    I'm Edward.

    Default

    Thanks Barry. Good to know.

    At least this way I know things will be safe.

    I may anyway open up the Metrum and have a look at what is behind the xlr outputs.

    Should be getting the decks back in a week or two. The Revox is already done and measures well within all specs.

    §
    Current: [P20] Roon/Tidal > Custom PC> Metrum Hex > Phast Pre > Neuro. 686 > Tannoy Berkley (RFC tweaks)


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