788T firmware revision 2.10 introduced the ability to link multiple 788T recorders for simultaneous, synchronous recording. It also allows linking the 788T with other Sound Devices 7-Series recorders including the 702, 702T, 722 and 744T. This is ideal for applications requiring higher track counts or synchronized backups. Important considerations for successful multi-unit linking include:
  • 788T C. Link linking requires setting the 788T to Connect As Mass Storage in the Setup Menu option FireWire/USB: Connection [# 2] . C. Link serial communication is disabled when Wave Agent CTRL (USB Only) is selected in this menu, though word clock and time code are transmitted and received.
  • Use a quality  RJ-12 cable to connect to the C. Link ports. An intermittent connection can result in audio dropouts and other problems.
  • Connect master and slaves via C. Link cables before powering. Power the master recorder before slaves. To ensure accurate synchronization after power up, allow the slave(s) time to fill up buffers and fully lock to the master before pressing record. 20 seconds should be more than adequate.
  • When linking the 788T with 702, 702T, 722, and 744T recorders with digital inputs used, configure the 788T as the slave unit and the other recorder as master.
  • Ensure master and slaves are set to the same sampling rate and time code frame rate.
  • Ensure slaves are set to Ext TC time code mode in the Time Code: Mode menu
  • Ensure slaves are correctly sync referenced:
    • The 702, 702T, 722, and 744T recorders automatically lock to an incoming sync reference. An ‘L’ lock indicator is shown in the main display when locked.
    • A 788T slave must be manually set to sync to incoming word clock in the Rec: Sync Reference menu. A ‘W’ lock indicator is shown in the main display when locked.
  • When changing sampling rates, power cycle both master and slave units.
  • When recording is stopped on the master, wait for a few seconds before commencing a new recording. If the slave is a 788T, wait until it’s ‘Media Notification: Writing to media. Please wait...’ message has disappeared.
  • It is not necessary to set the pre-roll on the slave units. Slaves automatically detect the master’s pre-roll value and apply it accordingly.

Sample Accuracy of Linked Units

There are three machine linking scenarios, each behaves slightly differently:
  1. 788T-to-788T Linking When two or more 788T recorders are linked, all linked inputs are sample and phase-accurate. No compensation is required between units.
  2. Linking multiple 702/702T/722/744T Recorders When two or more of the 702, 702T, 722, or 744T recorders are linked, all linked inputs are sample and phase-accurate. No compensation is required between units.
  3. 788T Linked to a 702/702T/722/744T Linking the 788T with 702, 702T, 722, or 744T recorders is time code frame accurate but not sample accurate. The 788T recorders analog and digital input circuitry is different than that of the two- and four-channel recorders. This results in a short, predictable, and constant digital delay between the inputs of linked machines. Since the delay  is constant, tracks are easy to align in a DAW. The chart below indicates the amount of delay the 788T has relative to the two- and four-channel recorders..

Chart of Delays

Input Type Sample Rate/kHz 788T Input Delay Relative to the 702, 702T, 722, 744T Recorders
All Analog 44.1 1.0 ms
48 0.9 ms
88.2 0.4 ms
96 0.3 ms
All Digital 44.1 3.5 ms
48 3.2 ms
88.2 1.6 ms
96 1.4 ms
An input delay can be set in the two- and four-channel recorders (in the input delay menus) to align the inputs of the machines. Use the table above to set the delay value. Note: when daisy-chaining audio from the outputs of one recorder into the inputs of a linked recorder, there is no need to apply delay.

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