Printing a track w FX = resulting track phase inverted?
 

I'm in the mixdown phase of a session, using some nice reverbs and - same old story - pushing the limits of what my laptop can do. So I've been printing a few tracks with effects so that I can deactivate the plugins on those tracks and free up more RAM for the reverb plugins.

I have a bass track with 5 plugins instantiated: Decapitator , some EQs and the Massey CT5 compressor. I created a new track and re-recorded (printed) the bass w FX on the new track.

Comparing the newly printed track with the original, something didn't sound quite right - I double checked buss/track levels, etc. The difference I was hearing was very subtle and I was tempted to ignore it and move on, but it kept nagging at me. Then I noticed that the wave shapes of the original track were tending to 'skew downward' from the zero crossing, whereas the wave shapes of the newer track 'skew upward'. (Please forgive this bonehead terminology - I don't know a better way to describe it).

So I used the Audio Suite "Invert" plugin on the new track - now the wave shapes follow the same general shape as the original track and, more importantly, it sounds exactly like the original track.

I've attached two pics below - the first is the track as originally printed. The 2nd is post "Inverter" plugin.

I'm stumped as to how the track got inverted in the first place - can anyone explain this?

Thanks!

Re: Printing a track w FX = resulting track phase inverted?
 

My first guess would be that you un-knowingly have the phase inverted on one of your pluggins. This can happen from time to time. IF you're using these plugs the waveforms shouldn't be identical anyways. As those should have processed the original waveform. I would go back over and double check that you haven't accidentally click the phase button (the little circle with a line through it)

Re: Printing a track w FX = resulting track phase inverted?
 

Dr Daw - thanks for the suggestion. I double checked and, as it turns out, none of the plugins instantiated on this particular track have a phase invert button.

Also, what led me to discover the phase issue in the first place was observing that the newly recorded track didn't sound quite like the source track. The source track sounds 'right' (as I want it to sound). To whatever extent the plugins have altered the original audio track, they haven't changed the 'downward orientation' of the wave shapes in the track display.

The phase discrepancy only manifested - both audibly and visually - when I recorded from the source track to a new audio track.

Any other ideas?

Re: Printing a track w FX = resulting track phase inverted?
 

Are you able to duplicate that result? Re-record as you did initially with the same results? If so, I'd begin taking the time to do that but with one pluggin at a time to see if you can isolate which pluggin is the culprit. Perhaps there's a bug in one of the plugs that is inverting the phase.

When you zoom in on the beginning of the waveforms are they in-line with each other, and 180deg's out? (one going up, the other going down)

Re: Printing a track w FX = resulting track phase inverted?
 

Have you deactivated all plugs and reprinted? Then turn them back on one at a time to find what's doing it.

Re: Printing a track w FX = resulting track phase inverted?
 

HA! Drew, we must've been typing the same thing at the same time.

Re: Printing a track w FX = resulting track phase inverted?
 

Thanks for the replies and suggestions. I went through process of elimination and the culprit is:

AIR KILL EQ!

Recording to a new track with any combination of the plugins currently on the source track - with Air Kill bypassed - yields a new track with wave shapes that roughly reflect the same shape and orientation of the source track.

But with Air Kill EQ engaged, the wave shapes of the new track are oriented in the opposite direction from the source track.

Pics attached.

So, this means that Air Kill EQ is inverting phase, right?

Re: Printing a track w FX = resulting track phase inverted?
 

I think you may have found the culprit, but again; when you're not zoomed in very close then it's hard to definitely say. The key is to check at almost the 'sample' level and check to see if one waveform is going up while the other is going down or vice versa. At the end of the day if it's parallel processing it'll matter, but if it's not, then it doesn't matter because the original would be muted/disabled.

If in fact 'Air Kill' is inverting the phase, then that would be a good thing to know for parallel processing. I would have a tendency to think you have found the culprit; but a zoomed in waveform would be better.

Re: Printing a track w FX = resulting track phase inverted?
 

Here's the zoom view!

Source track above, newly recorded track, with Air Kill EQ, below.

Re: Printing a track w FX = resulting track phase inverted?
 

YES! That confirms it, that Air Kill is inverting the phase! That's terrible!