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How to successfully clock to external clock source whilst using PURE DRIVE’s USB built-in audio interface on Mac


Important - before anything else, ensure your PURE DRIVE unit is running version v1.11 firmware or later! The v1.11 PURE DRIVE firmware is included in the V1.3 Firmware PackageThis firmware includes an important fix whereby PURE DRIVE gets stuck in ‘No Valid Formats’.


Once your firmware is up-to-date, please carefully follow these instructions:


If PURE DRIVE is connected to your host computer via USB and you want to clock to an external source – i.e. Wordclock Input (OCTO and QUAD) or ADAT (QUAD only), you must first set the internal clock rate of PURE DRIVE to match the external clock rate you are about to switch to and then change the clock selection on PURE DRIVE from internal to Wordclock In or ADAT.


Remember, when you are connected via USB, clock source switching must be done from AudioMIDI setup on your Mac, as the RATE and CLK front panel buttons are disabled on PURE DRIVE.


If the internal clock rate of PURE DRIVE does not match the external clock rate when the clock source is changed from internal to external, then it will show up with ‘No Valid Formats’ in Audio MIDI Setup on your Mac. To recover from this state, you must switch back to Internal clock.


Moving between DAW sessions at different sample rates

It is important to note that if you want to change the sample rate of the external clock (e.g. you are loading a DAW session with a different sample rate), you must:

  1. First set PURE DRIVE back to internal clock. Whilst on internal clock, set it to the new sample rate you are about to switch your master clock to.
  2. Change the sample rate of your master clocking device as desired (either manually or some devices change automatically switch upon DAW loading).
  3. Finally, change PURE DRIVE clock source from Internal to either Wordclock In or ADAT.

Note that the above steps should not be necessary if you are clocking PURE DRIVE via USB only and are not using Wordclock In or ADAT In to clock to. If you are using this method, please read Apple's information on succesfully clocking aggregate devices using Drift correction.