Something strange happened today. I Use my HEDD as the master clock for my system. The clock output from the HEDD goes to a Big Ben, and the Big Ben then distributes the clocking to:
(1) ProTools 192 I/O (and 192 Digital I/O)
(2) Rosetta 800
(3) DSP7000 (at 1/2 rate)
(4) Kurzweil DMTi interface (at 1/2 rate).
Today I tried to record a backing track from a CD into ProTools, so I set up a session at 44.1/16. I set the ProTools input to the optical out of the CD player (which is connected to the 192 Digital I/O). So, I am sending the CD digitally to the ProTools session.
I can watch the sample rate on the display of the Big Ben. The sample rate quickly went to over 45 and I got plenty of pops when I recorded in ProTools.
To try to figure out what was going on, I opened another 44.1/16 session and locked the sample rate at 44.10. Then I just played a track out to the monitors while watching the sample rate on the Big Ben display. The rate VERY slowly increased: 44.11, 44.12, 44.13, etc. This continued until I stopped the playback; at that point it was approaching 45.
I normally run sessions at 96/24 and this has not been happening in those sessions; the Big Ben stays locked at 96.00.
(1) Does this indicate a drift in the HEDD clock? Or is something else going on? Why at 44.1 and not at 96?
(2) The problem was much, much worse whn I tried to record a digital signal from the CD. What is going on here?
Probably something obvious, and I'll feel stupid when you tell me.
Any help would be appreciated!