I knew the sounds to be wrung from the VCS were quite varied, but they really did hit a pretty good set from pureish tones to heavy distorted noise.
The best way to get a full walk trough of the tones and pitches would be to write a tiny Atari ROM file for this. (It's really just about setting three registers.)
 Stella documentation and downloads (Win, Max, Linux, and sources) https://stella-emu.github.io/
I'd be interested in a deeper explanation of
div 15 -> 4 bit poly
5 bit poly -> 4 bit poly
I'm making a fantasy console, so I ended up spending quite a bit of time designing my own 8 bytes to describe a full range of
tone/freq/volume/envelope/bend. Packing expressiveness into a limited number of bits is quite a fun game.
There is an "about 30KHz" base frequency, so "div 15" suggests a 2KHz waveform; "4 bit poly" and "5 bit poly" are probably two of the "feedback taps", "and" a logical multiplication of these signals. But this is just my interpretation.
[Edit] For technical details see: https://alienbill.com/2600/cookbook/music/stolberg.txt
*) There is a 31,440 Hz clock frequency used to produce NTSC signals and 31,200 Hz for PAL consoles. This is probably also what is described as "about 30 KHz" in the manual.
I imagine it must be something wrong with the underlying emulator, but there's no audio output. visuals work, but not much else, which is sad for this bit of interesting code!