Yamaha O2R Owner's Manual page 214

Program 40 — VOCAL DOUBLER
This is a thin harmonizing effect obtained by setting a longer delay,
Parameter Setting
Pitch 0
Fine(1)
+5
-10
Fine(2)
Out(1) +100
Out(2)
+100
P a n ( 1 )
L 6
P a n ( 2 ) R6
+10%
FB.G(1)
-10%
FB.G(2)
Delay 60.0ms
Range
Same as program 39 Same as program 39
Internal Effects 111
Description
Digital Recording Console 02R User's Guide