Chris Johnson, aka Airwindows, continues to share his love for DSP with free tools, open source code, and elaborate discussions of the joy of crafting reverbs. So just in case you don’t feel blessed enough with free effects after SuperMassive’s new Sirius reverb/delay, here’s the tiny and the thick in all-new Airwindows editions. And they’ll even run in VCV Rack or on a Raspberry Pi.
This has implications not just for the free Airwindows plug-in, but other free and open source/libre projects incorporating Airwindows stuff (like VCV Rack and Surge XT), plus other combinations. And then there are the folks enjoying learning more about DSP and coding and just what makes their favorite effects tick.
First, late last month, there was VerbTiny:
The big, tiny idea? Unlike the “k-“series reverbs we’ve seen from Airwindows recently, which focus on acoustic simulation, this is about transforming the texture of the input sound. No predelay, nothing sophisticated, just some matrix math:
It was just another 4×4 matrix, but run through my testing, it made a sound that was weirdly intense with peak energy, beyond anything else I’d ever created. Just a lucky break (through spending days and weeks and months using genetic algorithm to evolve millions and billions of possible reverb matrices, so it’s not like it was only an accident). And that’s what’s in VerbTiny: that one algorithm for making a simple reverb.
Then there’s Airwindows VerbThic. As Chris explains:
All my other reverbs, very much including VerbTiny, are meant to sound as far back as possible. The whole reason VerbTiny came out is, I stumbled across a reverb algorithm for a 4×4 Householder matrix that had unusually high peak energy relative to RMS …
So imagine my surprise when I ended up with another algorithm, much like VerbTiny, even a fairly similar room size, except it was the opposite! It produced unusually LOW peak energy. In theory, this would produce a reverb that doesn’t sound far away: more like a fog that combines with sounds to thicken them up.
One of my Themes of 2025 has been raving about new ways of thinking about reverbs, so I love this, of course. I think we tend to teach reverb as a spatialization tool when it’s better to think about it as a sound processing tool, and focus on spatial perception as something we can manipulate after that.
And the other big story here is that this is all heavily optimized in terms of CPU and memory, meaning it’s well-suited to Raspberry Pi and other applications with constricted resources.
So here you go, it’s like an effects advent calendar or something.
And Goldilocks, go wild. Find just the one you need.
I like that he uses an E-MU Proteus sound, too; I’ve been digging into the vintage PCM Roland and KORG stuff precisely because they sound fabulous when combined with these more modern effects.
Enough writing. I’m back to playing with reverbs.
https://www.airwindows.com/verbtiny
https://www.airwindows.com/verbthic (download from this link — or newer — for the latest)
So tiny and thick.