Strange Phasing Behavior (MacOS BigSur only)

Can somebody please explain me the strange phasing behavior of a pure sine-wave?

Further more… how can this be switched off?

This test was made on my MacBook Pro MacOS BigSur v11.0.1

Not really sure what I’m looking at. There is some random phase settings on the osc settings for each new note, is that what you’re talking about?


First of all… a friend of mine that is working on a Windows PC doesn’t have the issue. This is good news for you and bad news for me.

2nd of all… I like your synth’s interface… I would like to use it.

Ok… now to the question:

SPL Hawk eye can visualize the panaorama/phase per frequency. The picture is a snapshot of a strange moving phasing that is happening with a pure sine wave.

You should not see any peaks… there should be a flat line and nothing in the correlation meter (the yellow thing over my “what the hell” text.

Does this work differently in other synths?
If you’re just playing a lower sine wave it doesn’t matter what phase the higher frequencies are at because they’re basically silent. You’ll probably see some phase noise because of the noise floor but it’s so low you would never be able to hear it.

Here’s how it should be… same setup with Serum

Look at it in the spectrogram, those harmonics you think are giving weird phase values are basically silent so it doesn’t matter what the phases are.

why should there be a noise floor? The analyzer is right behind the Vital instance.

I just tested the sine wave with different volumes. I get the peaks from -6dB. Hmm… strange

Regardig the phase… don’t you think that the Sine waves should cancel themselves out if you phase reverse one instance? This is behaviour that I expect… because then I know what’s going on.

In this case - and therefore I wrote here - I have no clue what is going on. Further more it can not be reproduced on every other system. One of my friends doesn’t have the issue… I do… an other one has it as well.

Does it matter? I don’t know… but If a the synth behaves unpredictable, the the result isn’t predictable.

Due to the fact that it’s almost 02:00h here… I have to sleep over it.

Tomorrow I will test it on my Studio PC - now I am on my MacBook Pro - and I will redo the tests.

So or so I thank you for your quick reply.


… are you sure you’re just playing a sine wave then?
Maybe you can save the preset and upload it here


It’s your Sinewave from the Basic Shapes… loaded on an standard initialized preset.

Sorry… I may not upload presets as a “new user” that is what the error message tells me.

ok… have to go and sleep a moment.

Is it possible to make a video? It’s possible I’m missing something.

You don’t want me to go to bed, do you? :sweat_smile:

Ok… let me see if OBS works on this Mac… just a moment.

Im curious to play that preset…
I can also test/take look with SPL HawkEye.

Upload to google drive or Dropbox and post the link :wink:

What about your Oversampling? 1x??
with 2x, 4x and 8x I see a flat line…

This is the best that I could do at 2am in the night… the video has no sound… but that’s in this case not needed.

I am using 2x oversampling… but there was no change in behavior when switching to it.

Just to let you know… I installed Vital and started testing. I didn’t change anything. It’s the basic installation.

You can have a look at the video… open an instance of Vital, select the Sine and play a note.

The amplitude of these frequencies are like -180dB. It doesn’t matter what phase they are in. They could have totally random phases and it wouldn’t matter because you can’t hear anything that quiet.

If you look at this in a spectrogram people have said that Vital has a lower noise floor than serum if you’re worried about quality.

But to reiterate, if a frequency is way below human perception, it doesn’t matter what the phases are.

Good morning

Ok… I made the exact same tests regarding the above described issue, but this time on my Windows Studio PC.

On Windows there is absolute no phasing issue. If there are two instances of Vital creating a sine wave and one gets phase reverted the cancle each other out - just as expected.

On MacOS BigSur v11.0.1 there is a phasing issue. If there are two instances of Vital creating a sine wave and one gets phase reverted the do not cancle each other out - this is a weird behavior.

To say that this phasing issue is not audible to humans is a wild guess… since I was running the test because each sound produced by Vital has had a special character I couldn’t explain. Now I have an explanation.

If this behavior is existing on all MacBook Pro i9 (and related to MacOS BigSur v11.0.1) or just to my installation, is something I can’t test - I just have 1 MacBook.

Wether or not this bug is worth to isolate and fix is something that you have to decide. Never the less it is a bug and it is existing on at least 1 MacBook Pro on the latest MacOS BigSur operating system.

From my point of view the problem is described as good as possible. I know that I can not realy use Vital on my notebook… but in the studio I can. I of course hope that there will be a solution, but if not I can live with it.

If there’s any further questions, please contact me. I’ll try to help as good as I can.