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  • SMPTE Pinout and Wiring

    Common Interconnection Wiring

    SMPTE LTC audio interconnections can be balanced, unbalanced or a combination of both.  Audio equipment varies considerably in this area.  There are four common connector types that you are likely to encounter, RCA, 1/4" pin Tip/Sleeve phone plug (1/4P-T/S), 1/4" pin Tip/Ring/Sleeve phone plug (1/4P-T/R/S), and 3-pin XLR.  The wiring lists below show the most common configurations for the various output/input interconnections.   

    Unbalanced line, Single conductor cable
    RCA and 1/4P-T/S to same
    Tip Signal wire 1
    Sleeve Shield

    Unbalanced line, Dual conductor cable
    RCA and 1/4P-T/S to same
    Tip Signal wire 1
    Sleeve Signal wire 2
    Shield on one end of cable only

    Unbalanced source to Balanced input, Dual conductor cable in all cases
    Unbalanced
    Output
    TO Balanced
    Input
    1/4P-T/S 1/4P-T/R/S
    Tip Signal wire 1 Tip Signal wire 1
    Sleeve Signal wire 2 Ring Signal wire 2
    Sleeve Shield
    1/4P-T/R/S 1/4P-T/R/S
    Tip Signal wire 1 Tip Signal wire 1
    Ring Signal wire 2 Ring Signal wire 2
    Sleeve Signal wire 2 Sleeve Shield
    1/4P-T/S 3P-XLR
    Tip Signal wire 1 Pin 1 Shield
    Sleeve Signal wire 2 Pin 2 Signal wire 1
        Pin 3 Signal wire 2
    3P-XLR 3P-XLR
    Pin 1 Open Pin 1 Shield
    Pin 2 Signal wire 1 Pin 2 Signal wire 1
    Pin 3 Signal wire 2 Pin 3 Signal wire 2

    Balanced source to Balanced input, Dual conductor cable
    Balanced
    Output
    TO Balanced
    Input
    1/4P-T/R/S 1/4P-T/R/S
    Tip Signal wire 1 Tip Signal wire 1
    Ring Signal wire 2 Ring Signal wire 2
    Sleeve  Shield Sleeve Shield
    1/4P-T/R/S 3P-XLR
    Tip Signal wire 1 1 Shield
    Ring Signal wire 2 2 Signal wire 1
    Sleeve Shield 3 Signal wire 2
    3P-XLR 3P-XLR
    1 Shield 1 Shield
    2 Signal wire 1 2 Signal wire 1
    3 Signal wire 2 3 Signal wire 2

    Balanced source to Unbalanced input, Dual conductor cable.
    Balanced
    Output
    TO Unbalanced
    Input
    1/4P-T/R/S 1/4P-T/S or RCA
    Tip Signal wire 1 Tip Signal wire 1
    Ring Signal wire 2 Sleeve Signal wire 2
    Sleeve  Shield Sleeve Shield
    3P-XLR 1/4P-T/S or RCA
    Pin 1 Shield Tip Signal wire 1
    Pin 2 Signal wire 1 Sleeve Signal wire 2
    Pin 3 Signal wire 2 Sleeve Shield

    ETC SMPTE Input Pinout

    ETC products provide a 3-pin female XLR connector for SMPTE.

    Pin 1 Com or Shield
    Pin 2 Signal +
    Pin 3 Signal –

    For balanced operation, connect source directly to input
    For Unbalanced input, connect pins 1 and 2 together in the user XLR 3-pin male plug, and connect "Signal" to pin 3. 

    ETC Unbalanced input cable end

    Pin 1 Shield
    Pin 2 Shield
    Pin 3 Signal wire 1