by Zorba the Geek » Mon Nov 21, 2011 5:56 am
Hi again guys,
Michael, sorry but I believe you are mistaken about the ability of the d8b to act as a word-clock slave without the Apogee clock card. As I mentioned on the 1st page of this thread, whilst both the ADAT and AES/EBU protocols are capable of carrying embedded clock information, the intended 'slave' machine must be capable of extracting this clock signal.
The d8b and the HDR are BOTH NOT capable of extracting their digital clocking signals from either of these protocols, but instead requires a word-clock input to be slave machines. As Mistahand's d8b only has the original clock card with no BNC connectors his d8b cannot therefore function as a word-clock slave, as there is no way to input or extract word-clock.
Mistahand's d8b could function as the master clock (with the older stock clock card) however this would mean that the slave machine (which could not be an HDR in this case) would have to be able to extract its digital clock from with the AES or ADAT stream. The Alesis HDR units can do this, many soundcards can do this (RME for example) and I believe the Mackie SDR had this capability, but it was a little flaky from what I can remember.
Michael's memory about the d8b acting better as a slave is related to another issue. A d8b with the newer Apogee clock card is often preferred as the slave machine when paired up with an HDR or MDR. This is because the clock output of the d8b Apogee clock card is undervolted and not very powerful, often leading to a lack of sync when cable termination is not taken care of or dodgy cables are used. In these circumstance the HDR/MDR's more powerful word-clock output is better suited to the task of being the clock master, and the d8b then acts as the slave. Note this still requires that the d8b has the newer Apogee clock card with the BNC input-output connectors.
One last quirk is the possibility of using the Apogee DIO8 cards in the d8b as a clock output. These cards (which are definitely not clock cards) have both ADAT and TDIF outputs (selectable within the d8b/HDR software) and also have a TDIF BNC clock output. This BNC provides an out of phase word clock signal specific to the TDIF format (I think it was 180 degrees out of phase by memory). Some people have tried to use one of these DIO8 cards in the d8b as a master clock source (usually occupying the first card slot I believe) to clock an HDR slave. Not sure about their success, but it may be worth searching the forum and the FAQ pages for more details.
Hope this helps guys.
Cheers,
George