Random clicks in a multi-track live session

[UpTilDawn]

So, I just started cleaning up tracks from an outdoor festival recording I made with my "new" remote PC. I've found numerous (though not a ton) of random clicks in the tracks, like the sort of thing you would get when the clock sync isn't steady. The wave drawing will look like two humps at the click instead of a typical wave drawing. The clicks appear random in the timeline, as well as on which tracks they show up, but when there's a click it's almost always across 4 or more tracks at the same instant and never randomly space in time.

I suspect that maybe one of the ADAT cables might not have been solid in the preamp racks (48 channels of Presonus Digimax, basically), but other than that, I can't think of what else might have caused this in a new computer... I tested it for over a week, using SAC as a front end with the SAW link. I noticed no lost buffers in SAC, but I remember hearing some of the clicks in the headphones during the concert. My focus was on the live mix I provided to the radio station, so I just took note of the clicks and didn't have time to investigate.

Anybody have any suggestions on what else might be worth looking at, if I set it up again in the shop?

[Bob L]

Bummer... can you narrow down all the clicks to one group of 8 chans that might belong to one of your 8 chan micpre units?

Your idea of a loose adat cable is valid... or a unit going bad.

Bob L

[UpTilDawn]

Bummer... can you narrow down all the clicks to one group of 8 chans that might belong to one of your 8 chan micpre units?

Your idea of a loose adat cable is valid... or a unit going bad.

Bob L

That's one of the odd things for me, Bob.
In the most recent band mix (with only 16 of 38 channels active), for instance, there have been around 5 or 6 click instances in over 50 minutes. The clicks do not happen on a regular timeframe and when they do happen, they are randomly distributed across tracks... One instance may be track 1, 10, 11 and 16, while the next instance may be just tracks 27 and 28.

That would seem to say that a single adat cable could not be the culprit, but I just can't say.

I wondered, also, if maybe I had left the LAN enabled... I can't say for sure, if it would be the cause and won't be able to tell specifically, unless it is on when I boot it back up to test (since I don't have an immediate need for it now) and there is evidence that the clicks occurred on the third/last day of the festival. So far, the clicks are popping up (no pun intended) on day one, but I seem to remember hearing some on more than one day.

The system is pretty trimmed out. It's the cloned XP drive from my original lunchbox PC. All hardware and software was updated as I proceeded through the build and checked again in the few days before the festival. I basically moved from a P4 to a Core2 Duo. It has very little software installed beyond what was needed to use it for recording and barely anything added since the new build. Testing before the gig was really good, with no major hiccups.

[Bob L]

It can be a tough journey chasing down a random type issue like this... you just have to try to test things one at a time until you can nail it.

The first big issue here is to try to determine if this is a hardware or software problem...

Is there one soundcard or multiples like two RME cards or similar... if so then there might be a clocking issue between them and sync may be slipping.

It sounds like from your description that the issues do not appear to be just clipping the signals, since you describe missing samples on the waveforms.

Keep at it.

Bob L

[UpTilDawn]

It can be a tough journey chasing down a random type issue like this... you just have to try to test things one at a time until you can nail it.

The first big issue here is to try to determine if this is a hardware or software problem...

Is there one soundcard or multiples like two RME cards or similar... if so then there might be a clocking issue between them and sync may be slipping.

It sounds like from your description that the issues do not appear to be just clipping the signals, since you describe missing samples on the waveforms.

Keep at it.

Bob L

Yep, you're right. There's no clipping... in fact sometimes the clicks are so soft individually that's it's difficult to see them in SF view without major vertical zooming - but you can sure hear them!

A pair of RME pci cards and 48 channels worth of mic pres, by the way.

I'll keep at it.... just no time to investigate at the moment, so hunting for things to look for when I do have time.

[Bob L]

If you are working at fixing the recording, try zooming in on the clicks and then marking a small area to the left of the click and then copying and pasting that small clean area over the click... that can usually clean up stuff like that without any noticeable artifacts since the pasted area is so small.

Bob L

[UpTilDawn]

If you are working at fixing the recording, try zooming in on the clicks and then marking a small area to the left of the click and then copying and pasting that small clean area over the click... that can usually clean up stuff like that without any noticeable artifacts since the pasted area is so small.

Bob L

I do that sometimes already. In fact, since you developed the ability to "slide" the waveform with the right-hold/drag idea, I will often make a small region around the problem and slide the audio from left, or right, depending on which blends best. That also works really well. It all depends - sometimes one method works better than another, depending on the content of the track.

I'm just beginning the first band mix from earlier in the day - getting rid of a buzzing channel at the moment - I'll see if I find any clicks in that set from 3hrs before.

[UpTilDawn]

So, just to update this thread...
After listening in detail to the entire 18-20 hours of recording over the 3 days,
it appears that the first day was the big one and almost the only one that had those random clicks. The second day had just 3-4 over a 3hr period and then nothing further.
The third day had none.

The weather was nearly ideal for all three days, with temperatures rising slightly after day one and humidity climbing a bit, but not nearly the sort of humid conditions we normally get this time of year. The equipment barely moved for the entire three days - only turning the preamp rack about 10 degrees every nite, so it wouldn't gouge the tarp and no one touched any of the connections to the preamps (especially in respect to the ADAT and WC cables) from the time I'd set up until I tore it back down.

I've not had time to set it back up and investigate, but my only guess at this point is that maybe one or more of the ADAT cables was not seated securely, or maybe I had left the Ethernet enabled on the first day....

So, I'll get another chance to re-test this new system in a few weeks, if not before that. Maybe I'll discover the problem, or maybe it's just gremlins.

[Carl G.]

I do that sometimes already. In fact, since you developed the ability to "slide" the waveform with the right-hold/drag idea, I will often make a small region around the problem and slide the audio from left, or right, depending on which blends best. That also works really well. It all depends - sometimes one method works better than another, depending on the content of the track.
.

Good technique also when used in combination with variable crosses (cntrl+x).

[andy cross]

I had a similar problem that was solved by disabling an internal wireless card. DPC Latency Checker is handy for investigating installations up to and including Windows 7.