Just wondering why db per octave matters for filters? Why does my Make Noise LxD have a 12db and a 6db option? I suppose because it indicates how aggressive the cutoff slope dives?
I think this answers your question:
Exactly. The dB per octave is an indication of how much harmonic content is removed from the signal. For whatever reason, you usually get 6dB per octave for every pole you have, so you typically see 6, 12, 18, and 24 pole designs. The general rule of thumb is 6 and 12 dB filters are great at shaping timbre in more subtle ways, where the 24 dB pole is for more dramatic effect or you really need to block out everything above that frequency as much as possible.