Strange clock problem connecting external synth


This is a strange one, and apologies if it’s me being ill-informed.

I am connecting my Kurzweil PC3X keyboard to Cubase via the MR816X:

  • Analogue out to analogue in works fine, if a little noisy
  • Kurzweil Digital SPDIF (via coax) out to Steinberg SPDIF coax in works perfectly (wonderfully quiet)

BUT, if I remove the analogue connection from the keyboard to the MR816X, the digital signal drops. Once I plug an analogue jack back into the MR816X, all works again fine after a couple of seconds.

On the Device Setup, I only get an option for SPDIF coax as Clock Source if an analogue lead is plugged in. Once it’s removed, the SPDIF coax option on the drop-down menu goes italic and the status light flashes for no-lock.

Why would the analogue signal from a synth make any difference to the MR816X’s ability to lock up nicely through the SPDIF coax connection?

Confused. Please help me out!


  1. do you use proper 70ohm coax cable for digital connection?
  2. did you connect both dig. in-out?
  3. how did you set the master clock ,which device is, what settings?
    (3 addendum)
    a. if you set the MR to internal then you have to set PC3 to ext in a Khz range that serves the MR’s internel clocking,
    b. if you set PC3 to internal then you must set MR to external or just always take care to set manually the correct Khz clocking value.
    either way you have to take care that both dig. in-out cables are in place.
    a is more flexible and care-free.