I struggled to find a working sketch that shows how to accurately isolate specific frequencies within a spectrum when using MINIM to analyse audio for responsive visuals.
Here's a template file that I'm using as a base at the moment, it's not much to look at but because a lot of examples I found were overly complex for my noob self, I stripped this down to the bare essentials using simple blocks, lines & points.
It's quite heavily commented and I hope it can be helpful to some. I'm sure it can be refined and optimised a lot more.
To tweak this sketch, first download it.
Make your updates, then upload your tweak!