u/DirCurrFluxDiode

I made a Ruby with a bassman mod per the schematics in ElectroSmash. Everything worked wonderful, the signal responses are great in the simulation. Now I went forward to try and add a tone stack, starting with just a simple low pass filter, following the example of the ElectroSmash article on the ProCo RAT, but I don't see a signal response as expected.

According to their equations, and given the resistor, pot, and cap I'm using, with the pot fully closed, I should have a frequency cut starting at around 109Hz, and when fully open, the cut should happen at around 564Hz, but that's not what I see.

When the pot is fully open, the cut seems to start at around 500Hz, and when it's fully closed, the curve is the same but everything is quietened instead.

What am I doing wrong? Why I don't I see a swing at the expected frequency?

By "musics like Ace of Spades and H.T. (this one)" I mean this very bottom-heavy speed-like metal that starts already at 100, and then from the solo onwards, it cranks to like 200kph.

My cardio playlist has these two songs at the back end, so I get reenergized at the end of my treadmill session, and I don't feel the aches, the exhaustion and the like nearly as much, and it would be even better if my entire playlist had the same vibe.