Weird behavior - Adding harmonics lower overall amplitude


There is a behavior that I find very confusing when using the sub harmonics features. When you add more harmonics the amplitude of the fundamental frequency goes down. Actually it goes down so much that the overall loudness of the signal goes down (as measured by your own view meter and my DAW confirms it).

It’s such an unexpected behavior that it feels like a bug to me. None of the additive synthesizer I’m familiar with behave this way. For example, the user harmonics of Ableton’s operator behaves as one would expect.

If that’s a feature, I would really appreciate an explanation and callout in the manual.


Sorry for the delayed reply.

It’s a feature yes, summing up the info you can find in the Manual ( Page 8 - Chapter 6 : Sub Controls ) :

The 8 harmonics sliders relate to the volume level of each partial from the harmonic preset you choose and the harmonic knob controls the volume level of the 7 partials following the fundamental partial.

So with the knob set to 0 you generate a pure sine wave, but turning the knob toward right generates additional partials, therefore affecting the output level since those partials model the volume level from measured drums.

You may want to tweak the amp section or/and engage the limiter to compensate the output level.

Thanks for your reply.

Unless I’m missing something, there is nothing in the documentation you pasted (and that I had read) that mentions the amplitude of the fundamental frequency will decrease as the knob is turned up. It only mentions that the amplitude of the additional partials will increase, which makes sense. What’s confusing is that the fundamental go down, hence lowering the overall loudness of the signal as the knob is turned up. This is not how additive synthesizer ever work, and this is not the behavior suggested by neither the harmonic sliders (as the fundamental is displayed as being at the maximum loudness), nor the wave display above the harmonics knob (as the wave does not shrink in overall amplitude as the harmonics knob is turned up).

For those 3 reasons, it’s very confusing and I suggest you either change that, or the very least make it extra clear in the documentation.

To my understanding this is because the harmonics partials generated when you turn up the knob are modelling the volume level from measured drums and therefore affects the overall output levels.

Maybe @phil_johnston could explain this better.