Blue Nebula User Guide, Rev A
Page | 7
THE PREAMP AND OUTPUT LEVEL CONTROLS
The three knobs to the right of the pedal
GAIN
,
PRE
and
MASTER
operate in a similar way to the
corresponding controls on a guitar amplifier.
Gain & Pre Controls
Rotating the
GAIN
control clockwise increases the signal level from the
1
st
input pair of JFET transistors
and will increase the harmonic content in the following
2
nd
pair of JFET transistors by driving them
harder and into asymmetric distortion – just as a valve triode does in a vintage tape echo. This control
needs to be used carefully in conjunction with the
PRE
control to ensure that the Blue Nebula’s digital
signal processor (DSP) is not driven into clipping indicated by the
CLIP LED
- which is located in the
panel between the
GAIN
&
PRE
controls - flashing momentarily. The
GAIN
control should be set for
the most agreeable harmonically rich sound and the
PRE
control used as described above to prevent
the DSP from being overdriven.
Master Control
This control should be used in conjunction with the
BYPASS
switch to ensure that the effects output
level is similar to the
BYPASSED
one. This ensures that you don’t have to change your guitar amplifier
settings as the unit is switched in or out of circuit.
