Boss DD-8 Reference Manual page 4

Panel Descriptions
8
8
[E.LEVEL] knob
This adjusts the volume of the effect sound. Turn the knob
clockwise to increase the effect sound. When set at the three
o'clock position, the effect is played at the same volume as the
direct sound.
* When the [E.LEVEL] knob is set to MAX while in REVERSE
mode, only the effect sound is output, with the effect sound
at the same level as the input sound.
9
[FEEDBACK] knob
This adjusts the feedback level. The number of times the delay
sound is repeated increases as the knob is turned to the right.
4
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* This cannot be used in LOOP mode.
* In GLT mode, this adjusts the depth of the GLT effect.
* Oscillation may occur when the knob is set at certain
positions.
10
[TIME] knob
This adjusts the delay time. Turning the knob clockwise
lengthens the delay time.
* This cannot be used in LOOP mode.
* The delay times that can be set vary according to the
position of the [MODE] knob.
11
[MODE] knob
This switches the delay effect.
12
[CARRYOVER] switch
This selects whether the delay sound remains (ON) or does not
remain (OFF) when you turn off the effect.
12