VST plugins are the most common format for Windows-based audio applications. There used to be some competing standards such as DirectX and DXi but most of those have faded away and VST remains.
Forte 4 supports the VST 2 standard. VST3 is on the radar screen but we just haven’t seen a tipping point yet that would force us to implement this. Most common plugins are still VST2 compatible and many are now x64 compatible too, which is perfect for 64 bit Forte 4. Of course, if you choose to run 32 bit Forte, you can use 32 bit versions of the VST plugins. Remember that the bit size of Forte and your plugins must match unless you are using some sort of “bridge” converter.
Unlike DXi or DirectX, VST2 plugins are just Windows DLL files and do not advertise themselves in the Windows registry. This means you have to tell Forte where to find your VSTs. We do this with the Plugin Manager, which you access in the Tools menu as “Manage VST Plugins”. This VST finder tool looks through the folders you specify for valid VST plugins and classifies them as instruments or effects. If a DLL is not a valid VST or maybe looks like a VST but fails some criteria in Forte (e.g. crashes when you load it), the Plugin Manager will add it to the Ignore list and usually indicate the reason it was added. You can always go back and retry it from the ignore list.
The VST2 spec is pretty loose and many plugins do many different things. Forte tries to be as compatible as possible with most of them but sometimes plugins do unexpected things. When this happens, we have several things you can try to get the plugin working. Please see http://www.brainspawn.com/documents/forte4help/plugin_compatibility_fixes_dev.htm for information on compatibility fixes.
Be aware that if you modify the DeviceCompatibility.xml file in the Forte installation folder, it will be replaced the next time you update Forte in that folder. Instead, copy it to your application data directory (where OPTIONS.INI) lives and Forte will pick up the modifications there too (and it won’t be overwritten on update.)
Also, be aware that the DeviceCompatibility file governs how Forte SAVES scenes, not how it loads them. On load, Forte simply replays the instructions in the scene, so unfortunately, if you change DeviceCompatibility, you will have to update your scenes to recreate them with the right VST data (e.g. FXP, FXB data, controllers, program change data, etc.). BTW, if anyone ever comes across a good set of rules for how VST hosts are supposed to know what to save off, let me know.
I hope this clarifies some things about how Forte handle VST 2 plugins.