Clicks and pops when external hard drive is connected.

[Milliarto]

I am running Protools 9 on an iMac 3.06 ghz Core 2 Duo, 4 gb of DDR3 ram, OSx 10.6.7

My interface is a firewire 1814 (drivers last updated in 2009). I have a LYNX converter I use for clocking and as an output to a summing mixer and the summing input back from said mixer.

Because there is only one firewire port on the back of my computer (firewire 800) I am forced to connect my hard drive into the spare port of my interface. I am able to connect my interface using a firewire 400 to 800 cable. Using any other configuration, such as connecting my hard drive first and then connecting my interface through the spare firewire port on the hard drive renders the interface inoperable.

I just set up a summing mixer in my home studio. Up till now I have only been doing editing and in the box mixing at home and my recording work has been happening at an HD facility elsewhere. Today I tried to use my summing mixer for the first time. I run ADAT out of the interface into my converter (my interfaces clocks from this converter), run the analog outs from the converter into the summing mixer, run the 2 track summing output from the mixer back into the converter and then run ADAT out of the converter into the adat input of the interface. My sessions are running off of a SETA drive that sits in an enclosure. When I try to record the summed mix back into a stereo track in protools, once in a while I get a weird digital error. It's not always in the same form. Sometimes it's a click or a pop but it's never a triangle wave (the way a clocking error manifests). Instead, it seems as though the waveform truncates. This might happen only once or twice during a 3 minute song but is nevertheless VERY annoying.

I have spent much of this day trying everything I can to fix the problem. I have reloaded all possible drivers, tried every configuration of connecting the hard drive and interface, defraged the harddrive, dumped digi databases and prefs, tried using a USB hard drive. Every time I get weird digital glitches. Sometimes I'll get all the way through a song only to move on to another and have the problem manifest itself AGAIN. Earlier in the day I moved one song folder to my main internal computer drive and tried to print and had no problems. I'm going to try it again now to make sure that my earlier success was not a fluke.

Has anyone experienced this problem? Is the firewire bus on these older interfaces simply not fast enough to write through? Am I going to have to move sessions to my internal drive whenever I want to sum them? This is a minor inconvenience but an inconvenience none the less.

Thank you so much for your help.


-Mikhail
P.S. I just saw that the Protools 9.0.3 update was released today. I'm downloading it as we speak but there didn't seem to be any fixes addressing my particular issue. Oh well...