Audio Levels At The Mixer's Stereo Out

[logic8mine]

I have a requirement of producing audio stems for a song sans effects on the stereo bus. In addition, the stereo bus must not clip when playing the project.

Without adjusting any track levels, the same song part (intro for instance) may clip @ +2dB. After restarting, it may clip by +0.3dB. A 3rd play thru shows +1.2dB. 

Can someone explain why there would be a fluctuation?

Edited May 23, 2023 by logic8mine
added file

[logic8mine]

another play thru

[fuzzfilth]

Since all but the top track are MIDI and not audio tracks, and you don't show the instrument slots, the educated guess is that you're using instruments which use either/or/and

- Round Robin sample assignnments which randomize the sample selection that's being heard

- free running modulation LFOs which cause different phase cancellations every time

- free running oscillators wich do the same in the audio range

all of which are designed to make the result less robotic and stale. If you don't like this, you can Freeze all MIDI tracks and audio tracks with modulation plugins to get consistent playback.

Edited May 23, 2023 by fuzzfilth

[logic8mine]

7 hours ago, fuzzfilth said:

Since all but the top track are MIDI and not audio tracks, and you don't show the instrument slots, the educated guess is that you're using instruments which use either/or/and

- Round Robin sample assignnments which randomize the sample selection that's being heard

- free running modulation LFOs which cause different phase cancellations every time

- free running oscillators wich do the same in the audio range

all of which are designed to make the result less robotic and stale. If you don't like this, you can Freeze all MIDI tracks and audio tracks with modulation plugins to get consistent playback.

Thank you for responding. In the past, I have found the culprit most often to be the drums, toms specifically, so I would suppose that's due to the round robin assignments- makes sense. I have not experienced this in other melody or harmony based software instruments. Despite R.R's, there is consistency levels.

I'll have to use the google to decipher what free running modulation LFOs and free running oscillators are. Anyway, I'll freeze the tracks and go from there.

 

[David Nahmani]

1 minute ago, logic8mine said:

I have not experienced this in other melody or harmony based software instruments.

This same issue can happen with synthesizers or samplers playing melodies or chords. In fact if you compare the peak detectors of the individual channel strips in your Mixer, you'll see that several of them have different readings. 

3 minutes ago, logic8mine said:

I'll have to use the google to decipher what free running modulation LFOs and free running oscillators are.

It just means that you have oscillators (oscillators either create sound, or in the case of LFOs, they modulate the sound) that are not synced to the grid, which means they don't oscillate exactly the same way with every subsequent playback, resulting in the sound being slightly different and not necessarily the same exact level every time. 

[logic8mine]

Thanks David, maybe I don't notice it as much on the individual tracks because while the peaks may vary in places throughout the project, the top peaks are either consistent or perhaps controlled by a limiter. The summed stereo output is a totally different animal.

I'll try these suggestions later tonight.

[David Nahmani]

The thing is that these differences can add up when summing multiple (different) tracks. Thats why you're seeing more of a difference on the sum than on individual tracks.