Perhaps all the graphs and stuff made this seem more complex than it really is. Literally all I was saying is that the default 24dB 4Pole filter with resonance set to zero will give a 12dB/Oct slope, and the Butterworth 4n with resonance set to zero will give a 24dB/Oct slope, etc. There’s nothing more interesting than that really going on here. Mainly, this was just intended to be a response to some posts and feature requests that sometimes pop up, where people ask for features which already exist.
Examples:
http://www.renoise.com/board/index.php?showtopic=20501
The confusion seems to stem from the fact that the filter names in Renoise are not labelled in a way that people might expect. Maybe people are following tutorials they’ve seen online or in magazines, which mention the need to use a “12dB/Oct highpass” or “24dB/Oct lowpass” to achieve a certain type of sound, and then when they come to Renoise they do not immediately find such an option. In these cases, I can understand some of the confusion and potential frustration that people might be experiencing.
For me personally, it only takes a few moments to experiment and see what is actually happening to the sound, but maybe it’s a good idea to think about renaming the filter modes slightly to avoid this confusion in the future?