With Aaltoverb 2 I added a MIDI input. This means that it won't be able to drop in and replace Aaltoverb 1 in current projects. Which, honestly, I didn't think through fully because it never came up in beta testing.
So very soon I'll be releasing an update that treats Aaltoverb 2 as a different plugin from version 1. This way both versions can coexist in your DAW.
Meanwhile, if you want to restore Aaltoverb 1, please use these installers:
If you've already installed Aaltoverb 2 version 1.0.1 or lower, where the plugin is just called "Aaltoverb," you may need to remove the plugin file manually before installing version 1.
On Mac OS: AU plugin files are in /Library/Audio/Plug-Ins/Components, and VST3 plugin files are in /Library/Audio/Plug-Ins/VST3.
On Windows, plugins should be in your VST3 plugins directory, C:/Program Files/Common Files/VST3.