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 |