Yamaha VL-7 Owner's Manual page 57

Lch High
L,R Delay
Rch High
Produces a natural decay in the high-frequency components of subsequent repeats.
The lower the value the faster and more pronounced the drop-off in high-frequencies.
Independent parameters are provided for the left ("Lch") and right ("Rch") channels.
R In
L In
Feature Reference Edit Mode
L,R Delay Effect Block Diagram
Delay
Delay
R Out
L Out