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Digital I/O and Clocking

iD24 provides one optical input, one optical output and one BNC word-clock output.

iD24 optical input and output

Optical formats​

Select the optical format in the iD application's System Panel.

Sample rateADAT channels per optical connectionS/PDIF
44.1 / 48 kHz82
88.2 / 96 kHz4 (SMUX)2

At 88.2/96 kHz, ADAT uses SMUX and carries four channels over the single optical link. iD24 does not require a second optical cable for its four-channel high-rate ADAT stream. The optical output can feed an external ADAT DAC or multichannel headphone-distribution system as well as another recorder/interface.

Clock source​

A digital system must have one clock master. In the iD application, choose:

  • Internal when iD24 is the clock master.
  • Optical when iD24 should lock to a valid incoming ADAT or S/PDIF clock.

When iD24 is externally clocked, the session/interface sample rate must match the incoming digital clock.

The external-clock status indicator uses:

  • Green: valid clock detected at the correct sample rate.
  • Amber: a clock signal is detected at a different sample rate.
  • Red: no valid clock signal is detected.

If a valid external clock is not available, resolve the cable/format/sample-rate issue before relying on the digital audio path.

Word-clock output​

The rear BNC connector is word-clock output only. It sends word clock at the iD24 operating sample rate (44.1, 48, 88.2 or 96 kHz), including when iD24 itself is clocked externally. Use proper 75 Ω word-clock cabling and terminate the receiving/end device as required by that device.

BNC word-clock output

Example: iD24 as master​

iD24 as clock master using a BNC word-clock connection
  1. Set iD24 clock source to Internal.
  2. Set the session/interface sample rate.
  3. Connect iD24 Word Clock Out to the external device's word-clock input, or use the optical output as the clock source if the external device supports it.
  4. Set the external device to its corresponding external clock source.

Example: iD24 as slave​

iD24 clocked from an external device through the optical input
  1. Connect the external device's optical output to iD24 optical input.
  2. Choose the matching optical format, ADAT or S/PDIF.
  3. Set iD24 clock source to Optical.
  4. Confirm a green clock-status indicator and matching sample rate.

Continue to Outputs and Hardware Controls.