Sorry, I assumed it was a different version.
The location of the dll file differs depending on the version, and in the case of 20201222 final, the file can be found in contents→modules→soundvoltex.dll.
The files are here. The file you find may be just an update.
http://teknoparrot.link.free.fr/multi/Sound Voltex V.html
If it is a complete file, there is a dll file directly under the contents folder.