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Electronic Theatre Controls Inc

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 Tip Shield
Ring Signal wire 2 Ring Signal wire 1
    Sleeve 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/S or RCA
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 Output
1/4P-T/R/S 1/4P-T/R/S
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

 

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