LOUD static/pop created during mix down

Installation & Configuration Mac OS X
#1

Short version: I’m getting a very loud “staticy” pop after recording automation for a track; it’s definitely related to automation because I replicated the problem several times on a couple of different projects. Any ideas appreciated; read on for the details.

Background: I’m using Ardour for OS X version 2.8.16 on fully updated version of Mountain Lion(10.8.2). The recording I’m working with is a live recording of the band that I mix for; I’m a “live sound” guy with very little recording experience and just now “learning the ropes” of recording. I actually do the recording on my old laptop(Acer Aspire 5100 running Ubuntu Studio) in Ardour for Linux because my Macbook won’t recognize my Mackie Onyx 1640’s firewire card for some unknown reason. Anyway I record on the old laptop and then transfer to the Macbook Pro(Mid-2009 13in MBP with 2.53C2D, 8gb RAM, 240gb SSD, ML 10.8.2) for editing because it’s a much faster easier to use machine. The live recordings tend to be around 20-30 minutes of audio that I go through and pick out the songs and assign each one a range marker with the song name. I only work with one song at a time and usually set loop points so I can let the song play on a loop while on the mixer screen setting up the plugins and fader automation.

Problem: I was working on mixing down a recording of the band(13 or 14 tracks) and had just went through and recorded fader automation for the lead vocal track(most tracks had one or two effects and some were routed through a bus that had my reverb plugged into it). When I went back to start at the beginning of the assigned loop there was an extremely loud “staticy” pop(registered 70+dB on the lead vocals channel); it occured right at the beginning of the song’s selected “range”. I ended up moving the range slightly past the noise(which persisted even after closing/relaunching Ardour and Jack) and recorded the automation for another couple of tracks. In the end all of the tracks that I recorded automation on had a similar pop at the beginning of the range. I ended up moving the range a little farther past all of the pops(which don’t register on the waveform BTW) and exporting the song.

I then started working on another recording, this time just an acoustic set with around 6 tracks. After setting up the plugins I started doing the automation again on the lead vocal and after I finished I had a 110+db pop at the beginning of the region I was working on.

Does anybody have any ideas? I can probably record the sound if you think it will help, let me know.

P.S.
Sorry for writing a book. Here’s a screen shot of the mixer readings after one of the “pops”

Thanks,
Tommy

#2

Just took at look at it and removed first the paraEQ plugin(no difference) and then the AUMultiband Comp(no difference). I then looked at the automation curve in the editor and noticed a sharp spike up in the curve where the pop was. After smoothing the spike to a gradual curve the pop went away.

Thanks for all the help,
Tommy

#3

Ok, I’ll remove the plugin and see what happens.

Thanks,
Tommy

#4

@seablade: Some of the free LADSPA plugins have no control interpolation and will be at risk of causing exactly that kind of problem when presented with a parameter step change, as may occur with automation (not a fault with ardour, entirely a plugin design issue).

#5

Well it seems that my image is too large and I can’t see how to edit the post, sorry about that. You might try right click>open in new tab to see the whole image.

Thanks,
Tommy

#6

Based off what I am seeing, my thought would be to remove the triple band parametric and see if it does away? Most of the time I have seen this it has been related to automation on particular plugins.

Seablade