A VST Instrument (or VSTi) is a VST Plugin that can convert MIDI events to audio. You can select a VST Instrument by clicking the instrument slot's down arrow. The VST Instrument plugins appear in the list's Plugins section.
A VST plugin will initially appear in both Effect and Instrument selectors. The first time it is loaded MultitrackStudio determines whether it's an effect and/or an instrument. From then on it will appear in the appropriate selector only.
VST Instruments look like VST Plugins. They have an additional Channel Selector. Some VST Instrument plugins respond to all MIDI channels the same way, in this case the channel setting doesn't matter unless you're recording using the Keyboard Mapper's split option or multiple keyboards. Other plugins, especially the ones providing many different sounds, do always require the correct channel to be specified.
VST Instruments respond to all the streams that are in the track's MIDI file. However, in most cases it will be easier to use multiple tracks (each using an instance of the VST Instrument) instead.
If the plugin has more than two outputs an Output button will be available. On clicking this button the Output Mixer window will appear. This mixer mixes the plugin's outputs down to stereo.
Tip (Pro edition only): The outputs of a multiple output VST Instrument plugin can be routed to tracks using sidechaining (see External Sidechain Routing). You can use this if you'd rather mix the outputs in the main window rather than the VST Instrument Output Mixer window. This is especially useful for drum plugins.
If a VST Instrument plugin gets in a bad state somehow you can press the F5 key (Windows) / Command-R (Mac) while the plugin interface is visible. This will save the settings, reload the plugin and load the settings again. This doesn't work while the track is recording.
MIDI 2.0 / MPE
VST3 instruments that support VST3 note expression receive per-note Pitch Bend, Volume, Pan, Expression, Brightness and Vibrato Depth. Poly Aftertouch is sent as well. VST3 instruments that don't support note expression will receive MPE just like VST2 plugins (see below).
A VST3 plugin that generates MIDI output can use note expression to send per-note controls.
VST2 instruments receive per-note pitch bend, per-note brightness and poly aftertouch via MPE. Switching to MPE happens automatically when per-note pitch bend or per-note brightness are sent to the plugin. MPE won't be used if you've set the per-note pitchbend range to zero.
Plugins may have an MPE mode setting that needs to be set manually.
Any MIDI output from a VST2 plugin is converted from MPE to MIDI 2.0. You can avoid this by setting the per-note pitchbend range to zero (in this case MPE to MIDI 2.0 conversion will only take place if the plugin sends MPE configuration messages (RPN 6)).