Left Channel stops passing audio

[montezuma]

Have any PT8 LE users encountered a problem with one channel of a stereo channel/bus no longer passing audio? I have been working on a PT session that uses a lot of busses (around 50 or so - I have the CPTK), and everything was going fine until a couple of days ago, when I heard a loud crack/pop in my left speaker, then noticed that the Master fader was only passing audio on the right channel (the one that didn't "pop"). However, all of my other mix channels appear to be passing audio ok (i.e. all other stereo tracks are showing levels in both channel meters, but the master fader is only showing levels in the right channel). I had not made any significant changes to the session - prior to the problem, I had only added the AIR Enhancer plugin on one track, and was writing a number of automation breakpoints in the Edit window....

I have tried trashing prefs & databases, toggling the Master fader input between "no input" and Out 1-2, making the master fader inactive and then reactivating it, exiting Pro Tools and reopening, rebooting my PC, changing playback engine settings, making changes to the "Bus" tab in IO setup, and I will admit that initially some of these remedies seemed to work - but only to have the problem subsequently reappear again. However, now things are at the point where NONE of these remedies are working anymore.

I was just wondering if any other of you PT8 LE users have encountered this, and if you found any workaround for this - it is a PITA!!

I notice that sometimes I can stave off this problem if I refrain from hitting the "return to zero" button on the transport control - it appears that this triggers the problem. And because this particular session does not start at bar 1 (bar 1 is actually a few seconds into the song - the session start is actually a negative bar number) could this be the cause of my problem?

I have checked my other sessions (that do not use nearly as many busses), and they seem fine, so it would appear that the corruption is only in this session.

Any thoughts?

[albee1952]

After what you described, I would test the speakers right away to rule out damage. Just open a blank session, add an AUX track(immediately pull the fader all the way down)and insert the signal generator plugin. Set it to PINK noise and -20 and push the fader up to a comfortable volume. Pan the noise left and right and verify that each side sounds the same(if it doesn't, maybe a speaker is damaged). Then PAN to the center, close your eyes and sit dead center and listen. If the noise seems to be heavier/louder on one side, that can also indicate a problem with a speaker. If all is well there, try trashing prefs and re-booting. Then open the session in question and solo some stereo tracks for a critical listen.

[montezuma]

Thanks, albee - I don't think my speaker is damaged; although I described it as a loud pop, I typically have my speakers and session volumes low (conversation level), and it didn't actually sound louder than the crackles I used to get when I had errors (before I cleaned up my system a couple years ago). However, you make a good point - it is still easy to check them because the pop only happened on one speaker, so a comparison of speakers will be fairly simply. I may try your white noise suggestion, just to be sure, but i'm fairly confident i'm ok on the speaker side of things - in my OP, when I stated that some of my remedies worked (albeit only TEMPORARILY), I forgot to mention that on these occasions the session played back on both speakers perfectly, and I could hear everything playing back panned to the correct area of the stereo field. Then of course, hit "return to zero" and - voila! - right channel only.

This problem is definitely in the session itself - it is not even systemwide, since none of my other PT sessions are exhibiting this behaviour. I trashed prefs (and databases as well) and rebooted numerous times, along with trying the various other things I described in my OP. and verified that all my other stereo tracks in the session are passing audio through both channels ok - it's only on my master fader, so the problem seems possibly to be on the main bus (which I labelled "MIX BUSS" - relabelled from bus 127-128 in my IO setup). I even deleted this master fader, made MIX BUSS inactive in the IO window, and then created a new master fader, and reactivated MIX BUSS, but to no avail.

Basically, I started this thread to see if anyone else in the LE world experienced this. I see something similar in a thread on the HD side of the forum (http://duc.digidesign.com/showthread...=busses+random), which from the number of posts indicates that something similar has been happening to the HD/surround guys for quite some time. However, I don't think any of the posters describe the "pop" that I experience prior to the loss of left channel audio, and in any event, I tried most of the recommendations on that thread as well (except of course for the ones relating to DSP chips, etc. which don't apply to my LE rig). I found ONE other thread (http://duc.digidesign.com/showthread...light=loud+pop), but these posters seem to describing the "pop", but not the loss of audio in one channel. So I started this thread to see if any other LE users have had this experience.

By the way, sorry about the long-windedness of my posts, but i'm trying to be as detailed as possible so that there is no misunderstanding or confusion over what i'm reporting.

Thanks, albee, for taking the time to respond, and I hope you and all the other DUCers (or is that AUCers??) are having a great Easter.

[montezuma]

So no one else has seen this problem?

[albee1952]

I've never had it. If you can nail it down to certain tracks, try importing the audio into a new session and see if the problem travels with the audio.(experiment with just importing the audio vs. importing session data).

[montezuma]

Thanks, albee - i'm certain the problem is not in my tracks (they all play fine when soloed), but in the Master Fader and the bus I am using it on. I've also confirmed that it's triggered only when I return to zero in the session (which has a negative bar #).

[montezuma]

Bump - so no other LE user has encountered this problem?