How the transformer object works
A transformer object checks whether or not an incoming event matches certain conditions. If it does, then certain operations are carried out.
Events that do not meet the conditions may pass unchanged to the output, or may be discarded.
The transformer can also make copies of matching events before altering them, and can split the selected (matching) events from the unselected ones, via its two top cables.
You must place the transformer in the MIDI signal path in order to use it.
Alter the output of an instrument
Cable the instrument output into the transformer (removing the instrument’s internal port assignment in the process).
Choose New > Instrument to create a new instrument, and assign it to the appropriate MIDI output port.
Cable the output of the transformer object into this newly created instrument (which, in essence, is simply acting as a MIDI output port).