Is it normal that my model bassdrum in plaits has a random behaviour?

Hello, sorry if this a repost but I didnt find any anwser.
It seems like the bassdrum model (the out one and not the aux ) has a random behaviour with its “harmonic” setting. It raises in volume and drive randomly.
I trigger it with marbles, I thought it was coming from the random lenght of the triggers but it does the same thing with a square as a trigger. Any ideas? Obviously this is with nothing patched.

Can you post a recording?

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Sure

And this is with the morph with a lot of decay.

It is probably worth checking that the attenuverter is set to 12 o’clock, so that the onboard lpg envelope isn’t modulating the setting.

All attenuverters at 12 o clock. A normal “frequency range”. It also occured with 2 different racks with different power supply (just in case).
There is nothing plugged or patched. All knobs at 12 o’clock except the morph (with a large decay, from 3 o’clock).
Its only with the out output and not the aux.

This is the normal behavior of a BD circuit that uses a resonant filter with a very high resonance.

An analog of this is pushing a child on a swing: depending on whether the swing is going backwards or forwards when you give the push, it’ll give it more energy and make it swing with a higher amplitude, or on the opposite it won’t have much effect.

Depending on the phase of the signal when you send the trigger pulse in the filter, it’ll “push” the filter louder or on the opposite barely has an effect.

This effect is less pronounced on vintage drum machines simply because they don’t have such extreme decay settings. You won’t notice it if the decay is sufficiently low for the notes to not have much overlap.

The other model (on the AUX output) uses an emulation of a frequency modulated VCO, instead of a pinged filter – a circuit that does not exhibit this effect.

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Makes sense. Thank you for taking the time to answer, and thank you for your work!