Subbass patch - sounds different depending on the key. Any advice how to fix this?

[nataliadata]

Hello to all the sound designers on this forum, I'm new here although not new to Virus TI. Would like to join in to the community and of course starting out with a possibly very basic issue.

I've found a very nice sub bass preset patch on Virus TI, called Simplex M. Fits quite well into a DNB track I'm making, but I discovered that the sound produces an oscillation or maybe it is resonance that "wobbles" the volume while the notes are pressed down for a second or two. It sounds sweet and well subby making my speakers shake... however the oscillation of the volume changes in speed depending on the key I press - it sounds faster on some and slower on others. Generally less frequent as I go to lower notes. Any possible ideas of what can be causing this change?

It sounds as though an LFO is controlling the volume of it or resonance, but the LFOs don't change their frequency. Some sort of self resonance? why does it change with key change? and how can I make it constant? I've discovered the "keyfollow" function on filter and all 3 oscillators and they are all set to normal... changes don't seem to affect the sound...

Any thoughts?? (or maybe some got a subbass patch that doesn't do this sort of unpredictable change?)

Many thanks in advance!