Oscilloscope alignment issues

[domtak]

I'm having some issues with the Oscilloscope and wondered if anyone here has a solve.

What I'm trying to do is align two sounds both in time and in phase - so they sound better together (kick and a bass note).

If I use the Oscilloscope tool and place it on the kick track (input A) and have it also monitor the bass track (input B) - they are out of sync (though they sound ok). When I use the time tool to nudge one of the tracks so they visually look in sync they the sound completely out.

I recreated a test to see if it was a plugin etc. and in a new Bitwig file I have a single track with an E-Kick on it. Following the E-Kick I have an Oscilloscope with input B monitoring the same E-Kick. They are never in sync regardless of whether I use PRE or POST on input B. See images below.




Shouldn't Bitwig be compensating for the latency - otherwise how is this usable?

Is this a bug? Is it me?

Help!!

THX

[Yokai]

I think there are a couple factors at play here. First is that in your test with the E-Kick, you're basically creating a feedback loop into the Oscilloscope. It's processing the direct INPUT signal passing in from the left (from the E-Kick), and then you're tapping the pre-fader OUTPUT from the Oscilloscope and feeding it back into itself again. Or, in the POST-fader tap, you're feeding the output of the track itself (post-fader) back into a device in that same track.

Bitwig (and every DAW?) is designed to prevent feedback loops because that can cause runaway resonance oscillation. So when you try to create feedback loops, Bitwig employs a few different ways to either block the feedback entirely, or put at least a 1-buffer delay (maybe more?) per your audio interface's current buffer size into the feedback loop to mitigate its potential for runaway oscillation.

Next, as to why your bass and kick don't line up exactly, I'm guessing it might in part be due to the trigger mode you're using in the oscillator. That keytracking trigger basically tries to zoom in on the waveform and set a window size according to the pitch of the MIDI note it's detecting from your keyboard. But it's not perfect. Your bass note might not be in the exact same pitch (off by a few cents) as your kick's body tone. Or the complexity of harmonics in the bass and kick is slightly throwing off the window size. Or there could be other good reasons.

Or it *could* be a bug? Email support@bitwig.com and ask them if this is a bug or to be expected. Then share the answer with us

Personally, I think that "Ext" option for the second "blue" channel of the Oscilloscope is mostly useful for looking at faster-moving waveforms--not for looking at two different keytracked waveforms?

And finally, the easy solution for checking whether your kick and sub or kick and bass are phasing badly with each other is to simply measure the SUMMED peak values when they hit at the same time. You'll need to turn off sidechaining to measure this. Solo your kick and notice its peak level. Then Solo your sub/bass and set its peak level to the same value as the kick. Then solo them both together and play them both together. If the SUMMED peak value is (roughly) 2.5-3 dB higher than when either of them are soloed, then they're essentially in phase. If the SUMMED peak value is only 1 dB higher, or 0.5 dB higher, or 1.5 dB higher, etc., then you have a phase problem.

[domtak]

Thanks for the awesome tip at the end - that's great and I'll give that a try. As for the other thoughts, I would hope it was feedback /mis-timing of the trigger mode - but the more I play with it the less I think it's either. I've messaged Bitwig - will see what they say.

[Tj Shredder]

In phase signals sum to +6dB...

[Yokai]

In phase signals sum to +6dB...

...if they are strongly correlated. If not, they might sum as low as +3dB.