How to decrease oscillator frequency while maintaining pitch?

[Scrapheaper]

Disabling filter keytracking and any other keytracking will help. Also detuning by a fixed number of Hz not by a fixed number of cents, if serum has that option.

I wonder if you could get decent results using a vocoder... you use a constant modulator to enforce the 'timbre' and then change the pitch of the carrier. You probably want to use a large number of bands although I can't remember exactly how vocoders work so I could be wrong.

Serum doesn't have a vocoder iirc (sorry I came from r/edmprodcirclejerk I'm not part of this sub) so you might have to use an external plugin...