9 pin D-SUB female connector to the controller
9 pin D-SUB female connector to the controller
The Alesis ADAT sync port is a 9-pin D-subminiature female connector introduced with the original Alesis ADAT modular digital multitrack recorder in 1991. It carries four balanced differential signal pairs — word clock, time code, control data, and response data — using RS-422 (TIA/EIA-422-B) electrical signalling, which specifies a minimum differential output of 2 V across a 100 Ω load and a receiver threshold of ±200 mV. The sync cable is a straight-through shielded dual-male 9-pin D-sub assembly; no crossover wiring is used. This port is a proprietary Alesis synchronisation bus and is not equivalent to Sony 9-pin (P2) RS-422 machine control, though some later ADAT models added a separate Sony RS-422 slave mode on the same connector.
| Controller Pin name | Controller Pin | Direction | Device Pin | Device Pin name | Description |
|---|---|---|---|---|---|
| Ground | 1 | - | 1 | Ground | |
| Receive A | 2 | IN | 2 | Transmit A | |
| Transmit B | 3 | OUT | 3 | Receive B | |
| Transmit Common | 4 | OUT | 4 | Receive Common | |
| Spare | 5 | - | 5 | Spare | |
| Receive Common | 6 | IN | 6 | Transmit Common | |
| Receive B | 7 | IN | 7 | Transmit B | |
| Transmit A | 8 | OUT | 8 | Receive A | |
| Ground | 9 | - | 9 | Ground |
Signals
- Ground — shield/chassis ground; pin 1 connects the cable shield
- Receive A / Transmit A — positive leg of the differential data pair (word clock direction depends on controller/device role)
- Transmit B / Receive B — negative leg of the differential data pair
- Transmit Common / Receive Common — common reference for transmit differential pair
- Receive Common / Transmit Common — common reference for receive differential pair
- Spare — function not publicly documented
- Ground — additional signal ground on pin 9
Notes
The sync cable must be a shielded straight-through 9-pin male-to-male D-sub cable. Alesis offered branded cables in 8 inch, 30 inch, and 30 foot lengths. The four signal pairs are carried on pins 2 & 6, 3 & 7, 4 & 8, and 5 & 9; pin 1 carries the shield. RS-422 balanced differential signalling allows cable runs up to 1219 m (4000 ft) at reduced data rates, though practical ADAT sync runs are short. No audio is transferred through the sync cable.