Chris Johnson of Airwindows has released Capacitor, a freeware filter effect in VST/AU plugin formats for compatible digital audio workstations on PC and Mac.
Much like the rest of the Airwindows product lineup, this latest plugin is a little bit quirky, but in a good way. It took me a few minutes to figure out how this simple 3-fader product was different from the standard high-pass/low-pass filter, but now I can definitely think of situations where it could come in handy.
Right off the bat, you’ll notice that it comes with a dry/wet knob which I always appreciate and rarely see on equalizers and filter plugins. While dialing in different amounts of the filtered signal, I didn’t perceive any phase issues that could potentially be a concern with this feature. Since the creator programmed the filters to simulate those on a synthesizer, you’ll find that rolling through cutoff frequencies is very smooth without any “zippering” artifacts or distortions.
Unlike other EQs, the Capacitor will never peak past the level of the input signal. In other words, if you used it after limiting to 0 dB, no clipping would occur from the filtering (although though I wouldn’t recommend trying this anyway). In the YouTube tutorial video embedded above, it is explained that there is a deep sharp notch at 14 kHz while using the high-pass filter. This is not something that can be toggled off and would be the main reason to use or not use this particular filter plugin in a given situation.
The programming behind this simple freeware filter is apparently based off of a non-typical algorithm which to my ear sounds pretty good. I would be interested in seeing an M/S option in the next build.
By the way, this is just one release among dozens of excellent freeware effects that Chris has been re-releasing for Windows lately. Starting as a Mac-only developer many years ago, he is now converting all of the tools available on his website to be compatible with both Windows and Mac OS. All of the plugins are now freeware as well! You can support the developer’s work on Patreon.
Capacitor is available for free download via Airwindows (316 KB download size, ZIP archive, 32-bit & 64-bit VST/AU plugin format for Windows & Mac OS).