You can change the default calendar event sound and all day event time. These settings are stored as part of each individual calendar.
Locate and open in TextEdit:
~/Library/Calendars/UUID.calendar/LocalDefaultAlarms/EventAllDayAlarms.icsalarm
~/Library/Calendars/UUID.calendar/LocalDefaultAlarms/EventTimedAlarms.icsalarm
The default all day event time can be changed to 6 am, for example, instead of 9 am:
TRIGGER:PT6H
You can change the default event time to values not available in the preferences. This can be a positive or negative value, for instance 3 hours before:
TRIGGER:-PT3H
The alert sound can be specified (without a file extension) using anything in your user or system sound folder:
ATTACH;VALUE=URI:Basso
Mac OS X Hints
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