You apparently recently added compatibility with IC2, but it doesn't seem to apply to IC2 Classic.
The machines make no sound, and the console is absolutely flooded with errors relating to the sound system:
https://pastebin.com/NGhBmbxu

It was for IC2 Exp. I'm gonna be honest, i forgot about IC2 Classic. I'll look into the issue.

Edit: In the meantime you can disable IC2 injection in the mod settings (in compatibility tab) to not get spammed in the console and get normal audio from IC2 Classic machines.

I've fixed it, Here's a build with the changes.