do you teach math in university?
No, but in a previous life I taught electronics math at a vocational college. That was a long while ago; we used slide rules back then!
Registration of ActiveX DLLs is a deeper topic than you might imagine. As a software developer, over the years I have had to spend a lot of time troubleshooting ActiveX problems such as unexpected interdependencies and version mismatches. Many late-night telephone conversations with on-site installers. They don't call it "DLL Hell" for nothing.
ActiveX DLLs differ from conventional DLLs in several ways. One of those differences is that it doesn't matter where the ActiveX DLL physically resides. Applications that call the DLL are able to find it by looking it up in the Registry, where the DLL has previously written crucial information such as where it physically resides.
The calling application doesn't refer to the DLL by name, but by a unique identifier called a CLSID (class ID). Every DLL must have a unique CLSID. Cronus.dll's CLSID is "{0E7C41F0-68A2-45F5-B9C2-CC37BA99810D}", quite a mouthful. But that's how V-Vocal is known inside the computer, not as V-Vocal or cronus.dll but as "{0E7C41F0-68A2-45F5-B9C2-CC37BA99810D}".
Maybe that would be a cool forum handle. Just call me "{0E7C41F0-68A2-45F5-B9C2-CC37BA99810D}" -- or just "0E7" to my closest friends.
This is what is meant by "registration": the DLL is checking in and introducing itself to the Registry. When you invoke the REGSVR32.EXE utility, it's simply calling the DLLRegisterServer function within the target DLL, which every ActiveX DLL must include. DLLRegisterServer creates some registry keys under HKEY_LOCAL_MACHINE, the most important one in \software\classes\clsid, where the DX/DXi writes its unique CLSID, its primary entry in the internal "phone book".
Software installation programs normally take care of this as part of the installation process. Sometimes, users fix problems by re-installing software packages, which can be quite time-consuming when all they really needed to do was re-register one or more DLLs.
If you're not sure if a DLL is ActiveX or not, just run REGSVR32 against it. It doesn't hurt anything if it's not an ActiveX DLL, it'll just tell you that the DllRegisterServer entry point was not found. It also doesn't hurt anything if the DLL has already been registered (as long as you're re-registering the
same DLL - you can get into trouble if you have multiple versions of the same DLL on disk; re-registering a different one de-activates the previous one.)
Cakewalk gathers most DX (ActiveX) effects and instruments under a folder named "shared dxi" under the main Cakewalk folder (usually program files\cakewalk). In there you'll find V-Vocal and most of the other DXi's such as TTS-1 and Dreamstation. Not all of the DLLs in there are ActiveX, though. V-Vocal, for instance, consists of 3 DLLs, only one of which (cronus.dll) requires registration. But again, there's no harm in attempting to register a DLL that doesn't need it or re-registering one that's already been registered. So register away.
Want to explore further? DLLs often call other DLLs. Those other DLLs are called "dependencies", because the top-level DLL depends on them to be present in order to work properly. Sometimes, an ActiveX DLL will fail to register because a dependency is missing. Or worse, the DLL registers OK but subsequently crashes because a dependency is missing.
There is a tool you can get from Microsoft that shows file dependencies for any DLL or EXE. It's called DEPENDS.EXE. If you run Depends against cronus.dll, you'll see that cronus relies on 10 other DLLs, and each of them has their own dependencies, and their dependencies have dependencies. Fortunately, for cronus.dll the dependencies are standard Windows files, so they're unlikely to be missing.
DEPENDS.EXE can be fun. OK, fun if you're a total geek. Use it to see what dependencies SONARPDR.EXE has - a boatload of 'em!
Mmm, this was kind of a rambling response, but maybe it's piqued someone's curiosity and taken a little mystery out of DXi registration.