Chony...
If you use the Input Transformer (if that is still in the new Cubase, I know it from VST5) you set up a filter that ONLY (Equal) selects the note number of the crash cymbal, THEN multiply the velocity by 0.75. That will do it in realtime (on input).
OTOH, if the part is already in Cubase, you Option-click on the note in the key editor (possibly different on a PC, but it will be in the manual... look up 'select all equal notes'), then you can use the Transpose and Velocity editor (command-h on a Mac) to divide their values, or add or subtract, whatever.
That key command, where you modify-key select one note, and it selects ALL the notes of that note number (in the Part), is one of the most useful key commands to learn, for editing drum parts. You CAN do it in the Drum editor, simply by selecting one drum note to edit, but I prefer to do everything in the same key editor, I'm not a huge fan of the Drum Editor page...
Hope this helps.
[This message has been edited by Diki (edited 07-22-2008).]
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An arranger is just a tool. What matters is what you build with it..!