CMX autopanning

I am using cmx to create a stereo acoustic guitar track. 100% wet, 100% panning, minimal delay and pitch change. The result is a guitar track that randomly pans around the stereo spectrum. Could someone explain why that is? I can see why it might be part of the algorithm, but in this case it is undesirable.

So, things happen fast around here yeah? :wink:

Sorry for the delay, we were kidnapped by aliens last week. Randomness isn’t part of the algorithm, but I can think of a few technical reasons why the stereo image of the output might appear to move. Would you mind posting a few seconds of the input audio so I can check it out?

Settings are 100% Wet, 100% Color, 100% Wide, Left channel (-1 cents, 5ms delay), Right channel (+1 cents, 5ms delay)

Sorry, I meant the dry audio please, so I can recreate?


Thanks for the clip. This won’t be a very satisfying answer, but I think the stereo panning effect is purely technical in this case. Because the input audio (aka the nice guitar playing :slight_smile: ) stays on the same dominant for a while, the 1c pitch shifts up and down form a slow stereo phase cancellation cycle (which can be seen in Schope’s phase view), which the ear picks up as the sound slowly moving around the stereo image. The effect only happens with a consistent dominant pitch on the input, and tiny pitch shifts.

That’s a long winded explanation, the short version is, this effect isn’t built into the algorithm, but is a side effect with this particular combination of input audio and CMX settings. It won’t go away unless you increase (or zero) the pitch shifts, which of course will change the overall sound, so it may be that the particular result you want isn’t possible in CMX without the stereo effect.

Thanks Schwa

I am confused by the fact that both the left and right channel should be playing a static audio track (although slightly pitch altered). Or am I wrong and there is actually some modulation going on. Either way, great plug in most of the time. A shame it can’t do this as it was so close to being exactly what I wanted. Thanks for the answer. :wink:

You understand it right, there’s no modulation. With your settings, there’s a static 1c pitch-shift up and down, spread left and right. The waveform peaks in the pitched-up channel are identical to the waveform peaks in the pitched-down channel, but a little closer together. Because the input audio stays on the same dominant pitch for a while, the channel peaks slowly move from being lined up like this (this is your actual guitar part):

to being offset like this:

Which causes the stereo phase to slowly move between being centered:

And phase-cancelled left/right:

Which causes the auditory sensation of the sound moving slowly within the stereo image.

Thanks again for the explanation. Not sure I fully understand what is going on, but I accept it :wink: