How to make XLR to Phono / RCA Cable

Discussion in 'Member 'How To' Guides' started by Tenson, Mar 28, 2011.

  1. Tenson

    Tenson Moderator

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    This type of cable connects a balanced XLR connection to an un-balanced RCA plug. This is not a problem because XLR connections have a positive and negative signal which are the exact opposite of each other, and a ground connection for the cable screen. An RCA / phono connection simply has a positive connection and ground for the screen.

    There are however two ways to make this type of cable and the correct method depends on the equipment with the XLR connection and whether it has a 'quasi-floating balanced' connection or a plain 'balanced' connection. Quasi-floating outputs are the most common and should have pin3 of the XLR connected to ground. Plain balanced outputs should have pin3 of the XLR output not connected to anything.

    Quasi-floating outputs sense if pin3 is connected to ground and output their full voltage only on pin2. Plain balanced outputs do not do this, and if you connect pin3 to ground, the voltage will still flow from that pin and being connected directly to ground will cause that output device to distort and put a lot of noise on the ground line.

    Quasi-floating outputs:

    [​IMG]


    To make this you need some un-balanced calbe. I'd recommend Sommer Cable Session MKII: Session MKII

    Alternatively I also recommend Klotz AC110: Klotz AC110

    One end of this cable with the RCA plug is done just as this RCA cable tutorial shows: http://www.audio-forums.com/as-rediect/showthread.php?t=28016

    The other end must be done as per the diagram above. Pin1 and Pin 3 of the XLR must be joined together, and connected to the outer screen connection of the RCA plug. Pin2 of the XLR must connect to the centre of the RCA plug.

    Take the XLR plug apart and slide the plug body over the cable to it can be screwed back onto the plug assembly when finished. Strip your cable insulation back and twist the screen wires together.

    [​IMG]
    [​IMG]

    Strip the centre conductor insulation back. When pulling the cut insulation off, I'd recommend holding the centre conductor with pliers so it doesn't slide inside the outer sheath. Now apply a little solder to the twisted screen wires and the centre signal wires. Also get the plug assembly held in a small vice or ap air of pliers with a rubber-band around the handle to make it grip.

    [​IMG]

    Now solder the screen wire to Pin3 of the XLR.

    [​IMG]

    Next, bend that screen wire over to touch on Pin1 of the XLR and solder that. You might need to use a decent blob of solder since the wire is not actually inside the Pin receptacle.

    [​IMG]

    Now bend the screen straight and solder the centre conductor to Pin2 of the XLR.

    [​IMG]

    Now pop the plastic retainer clip on the cable. It compresses when the plug body is screwed on to the assembly and holds the cable tight to stop the connections being pulled.

    [​IMG]

    Screw the plug together, and done!

    [​IMG]

    Plain Balanced Outputs:

    The connections for a plain balanced output should be made like this. Pin1 of the XLR to the outer ground connection of the RCA, Pin2 of the XLR to the centre signal connector of the RCA, and Pin3 of the XLR left floating in open space not connected to anything.

    [​IMG]

    Do everything as above, but do not connect the twisted screen wires to XLR Pin3; connect only to Pin1.

    [​IMG]
     
    Tenson, Mar 28, 2011
    #1
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