Yamaha VP-1 Owner's Manual page 130

Important
• If Controller Init is "off", the sound of a newly selected voice will depend on
current controller settings — and in some cases may be different than expected.
• Vibration from the keyboard or a speaker may occasionally cause a controller to
shift slightly. If Controller Hook is "off", this shift may cause the controller to
become effective, producing an unintended and possibly jarring change in the
sound.
FYI
• The VOICE SETUP function's "Detuning" (
REFERENCE: 1-24) values operate relative to the "Master Tune" setting described above.
REFERENCE: 1-23) and "Noteshift" (
REFERENCE
Chapter 2 SYSTEM Mode
SYSTEM Functions
2 - 5