Would it be possible to add a “invert” output to the filter device? I guess the inverted output of a lowpass would be different from just turning it into a highpass filter. Besides new effects and sounds this would surely be usefull to do things like very accurate mutli-band compression for example.
Furthermore I’d really like to have a 12dB and 6dB filter (back) in the current filter device.
Anyone with me?
-BA
This is something that I’ve experimented with a bit in the past, by mixing a phase inverted signal back into a filtered version of itself, so that it partially cancels out and essentially achieves what you’re describing:
http://illformed.org/temp/invert-filter-example.xrns
I started a thread a while ago that you might find interesting:
Thanx dblue. I knew about the inverting by Gainer. I just think it would be easier and more performance friendly to output the filtered (cut) signal direct from the filter.
Anyway, I didn’t know the butterworth4 is that close to a 12dB filter. Thanks for the link and the interesting article! 
Still, the butterworth is not capable of producing resonance like a normal 12dB filter. So still my wish… 6dB and 12dB (resonance-)filters, pleeeaaase.