Airwindows has released Slew2, a free clipper effect plugin for Windows and Mac.
Slew2 lets you limit or wipe out the highest frequencies, near the Nyquist frequency.

This plugin is just the anti-aliasing technology I was experimenting with in 2010, applied to Slew, my simple slew clipper. I thought it was going to make the slightly grungy Slew smoother (Slew is a clipper, and can be expected to have clipper-like qualities). That anti-aliasing code was a bit odd. It’s possible I made a mistake somewhere.

If so, I’m keeping it, and now what I invented is out for VST also, and free to all.

Slew2 doesn’t act anything like Slew. What it does, is it puts a particular behavior on the extreme highs. Set to an intermediate value, it’s an acceleration limiter. Cranked all the way up… well, check out the video. It behaves like one of the nodes in Average (also coming to VST) with a 100% cancellation, but the point of total cancellation is also the Nyquist frequency. Slew2 produces a very natural-sounding brickwall filter exactly at that frequency, with the response falling off faster and faster until it’s totally gone when you hit the Nyquist limit (digital sampling theory: at 44.1K (CD quality) it is 22.05K where the treble cuts off).

Slew2 is available as a free download for Windows and Mac (VST/AU). You can support Chris at Patreon.

More information: Airwindows / Slew2