SubLab: What is this Low-Frequency Oscillation and how can I stop it?

Hi everyone, this is an excellent synth, but there’s something been driving me nuts…

Here’s the LANDR waveform graphic for a full track using SubLab. I don’t know how LANDR produces the graphic: if you’re familiar with them you’ll know it’s a different visualisation to a regular waveform, but it’s useful enough for catching this issue.

Those big spikes are SubLab. It’s playing the same two notes at the same velocity, but notice the oscillation over time. That’s unwanted but I can’t iron it out.

[part 2 - new users can only include one embedded pic per post]

Here’s the same track in Soundcloud. Different graphic but you can see the effect of the oscillating bass over time.

[part 3]
Here’s another example. The bassline was more complex, but there was nothing in it to warrant the waves you can see in the graphic.

[part 4]

Here are some steps to reproduce the issue.

Macbook Pro 2019, High CPU and RAM. Maschine 2.11.0. SubLab 1.1.2.

Test 1: Patch, Staccato
Patch: “Sub Guap” from Richie Souf, out the box.

Step 1: Play the same note(s), same velocity, staccato, for a few minutes:

[part 5, test 1 cont.]
Step 2: Export and analyse:

Expected result: flat waveform over time. Actual result: oscillating waveform. Boo!

[part 6]
Test 2: Patch, Legato
Patch: “Sub Guap” from Richie Souf, out the box.

Step 1: Play the same note(s), same velocity, legato, for a few minutes:

[part 7]
Test 2, Step 2: Export and analyse:

Expected result: flat waveform over time. Actual result: flat(ish) waveform over time. Yay!

[part 8]
Test 3: Edit, Legato
Patch: “Sub Guap” from Richie Souf.

Step 1: Edit the patch. On the x-sub tab, slide the harmonics all the way down, and slide the lows all the way up.

[part 9]
Test 3, Step 2: Play the same note(s), same velocity, legato, for a few minutes:

[part 10]
Test 3, Step 3: Export and analyse:

Expected result: flat waveform over time. Actual result: looks like there’s one signal remaining constant and one which is oscillating?

I had a couple more tests but I’ll spare you the hundreds of comments :slight_smile: Essentially the issue arises when (low) sub and synth play together, on this particular patch anyway.
Another factor is, playing one note before the envelope has fully released the previous note. Not sure how that affects the issue exactly, but it changes the results.

Thanks for your time. Any possible workaround or fix?

Respect!

Update: I got the same results from testing kick drums in Maschine, so I raised it on the Maschine community and got this reply https://www.native-instruments.com/forum/threads/exported-audio-is-fluctuating-oscillating-inconsistent-how-did-these-waveforms-get-so-wavy.424383/#post-1990565

“Another factor is, playing one note before the envelope has fully released the previous note”

What happens here is that instead of resetting the wave back to 0 phase when the new note comes in, because the envelope has not fully released and you have a volume from the envelope >0, synths will avoid a click (going from what ever value it is at directly to 0 instantly while you have a volume that is not 0) by not resetting the phase of the oscillator. This is what I think you are seeing.

We’ve got a version upcoming 1.1.4 that has some changes to how this works, where you can turn on/off the reset.

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Yes! Thanks Gavin, good shout. Sounds about right, I’ll look out for the new version. Peace!