Word Clock Hell...

[KineticSound]

I need some troubleshooting help, gentlemen!

My new rig has been working flawlessly for months now, until today when my word clock decided to drop out unexpectedly (in the middle of a project, of course), and I've tried everything I know how to fix it with no luck.

My clock source is on the ADC card for my Focusrite Platinum preamp. Clocking information runs imbedded in S/PDIF to the digital input on a TASCAM FW-1082 controller/interface, which is connected to my Mac via Firewire.

The TASCAM has only two options for WC sync: internal clock or S/PDIF clock (basically, it either generates clock or reads clock info on the S/PDIF port; unfortunately, it has no BNC jacks for dedicated WC).

Obviously, the TASCAM will only read digital input information from its S/PDIF jack if it is locked to the S/PDIF word clock. If it can't read the clock info, the digital jack is disabled.

I mixed down a session in Logic, started a new file, and got the dreaded "pop" in the headphones... the WC signals went out of sync, and the "clock" indicator on the TASCAM started to flash (indicating that it could not get a good clock signal).

I shut everything down, rebooted the Mac, turned on the preamp (WC master), then the TASCAM. Still no WC sync. I shut down again, tried the process in reverse: Mac, TASCAM, preamp. Still no dice.

I tried powering down only the TASCAM, then back. Then the same with the preamp only. Still no WC sync.

I tried setting the preamp clock to a different sample rate and matching that sample rate in the TASCAM's software control panel. Still no luck.

EDIT: Also tried swapping S/PDIF cables to check if the cable was bad - no difference. Tried updating the firmware via TASCAM's site - no change.

Any other ideas of what you guys might try to restore the WC sync???

 

[SouthSIDE Glen]

I don't have a definitive answer for you, but based upon your description and steps so far, I'd look at two things next:

First, you make no mention of checking the clock status in the Focusrite itself. I don't know how that particular device is set up, but I'd imagine there's ought to be a way of telling the Focusrite whether it's master or slave - either via hardware switch or via software/driver access. I'd check to make sure that hasn't switched over to slave mode.

Second is a similar question/issue regarding Logic on your Mac. Is that new session set so that it thinks it is providing the master clock, possibly confusing your Tascam?

Either way, or even if neither seems to make sense, the first thing I'd do to troubleshoot is simplify the chain and take it one link at a time:

In this case, I'd try first getting the sync working between the Focusrite and the Tascam first, leaving the Mac out of the equation. As you describe your tests, you have had the Mac started up first in both tries. I'd leave the Mac down and just try first to see if you can get stable sync between the Focusrite and the Tascam.

If that doesn't work - i.e. if your sync light on the Tascam stays flashing - then try the reverse; remove the Focusrite from the chain altogether and try setting up your system to let Logic master the clock for the Tascam (if you can do that via Firewire). If that still does not work, then I'd start suspecting the Tascam internals since you have tried two different clocks and the Tascam still malfunctions. If, however, that does work, then the focus (pun intended) would be on either the Ficusrite or the S/PDIF input on the Tascam. (That last one can be tested if you have S/PDIF clock available off your Mac instead of mastering through the Firewire.)

G.

 

[KineticSound]

Glen,
You are a voice of reason, thank you! I was frustrated in my OP, and left out that: 1) The Focusrite has two clocking options, external sync via BNC (slave) or internal sync at 44.1, 48, 88.2, or 96kHz (master). The internal options automatically send word info via the S/PDIF output. 2) The TASCAM has similar options, the difference being the external sync is only available via S/PDIF. This can be frustrating, because when you're troubleshooting a problem, you can't tell if it's the digital signal itself that isn't working or the clocking information - because the only read option combines the two on a single port and it (the TASCAM) ignores the digital input if it can't find a valid clock signal to sync with.

On your suggestion, I shut off the Mac completely, powered up the Focusrite, then booted the TASCAM in "Monitor Mix" mode, which basically uses the control surface like a digital mixer. I used a manual word rate setting (there's a way TASCAM allows you to do this by holding "shift" and pressing the "D-In" option, then a corresponding eq key to toggle between the four different word rates) and voila!, the clock indicator flashed a couple of times and sync'ed right up.

Then I booted the Mac and Logic back up, switched the TASCAM back to "Computer" (control surface) mode, and everything stayed sync'ed up. Based on your advice and the resulting outcome, I have to assume that there was something done on the TASCAM's software control panel that it didn't like...

Thanks a million! I would say I owe you one, but at this point I owe you more like a dozen or so...

 

[SouthSIDE Glen]

Glad it worked out for ya! Though it sounds like you probably did most of it on your own with th re resetting of the clock setting on the Tascam. But yeah, that still is part of the whole "try to isolate the problem by breaking it down into pieces" strategy.

As far as owing anything, all I have to say is...

[time out while I stuff a couple of pounds of cotton in my cheeks and start playing the violin piece from 'The Godfather']

... Someday, and that day may never come, I'll call upon you to do a service for me. But, until that day, accept this justice as a gift on my daughter's wedding day.



G.