MOTU 4pre, User Manual

Page: 58 / 82

C U E M I X F X
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Choosing a channel to display
The FFT window follows the currently chosen
Scope channels (Figure 9-1 on page 52).
View controls
You can show and hide the FFT display and
spectrogram as desired using the
View controls
(Figure 9-7).
Figure 9-7: View controls
☛
The Show EQ controls item is for other MOTU
audio interfaces and is grayed out for the 4pre.
Spectrogram
Click the Show Spectrogram option (Figure 9-7) to
superimpose a real-time spectrogram “waterfall”
display in the background of the FFT display, as
demonstrated in Figure 9-5.
The spectrogram scrolls from top to bottom, where
the top edge of the display represents what you are
hearing “now”. Color represents amplitude along
the left/right frequency spectrum. The amplitude
color scale runs from black (silence) to red (full
scale) as follows:
Figure 9-8: Spectrogram color-to-amplitude spectrum.
Also see “Spectrogram controls” on page 59.
Logarithmic or Linear X-Axis Scale
The x-axis defaults to a logarithmic scale, but can
be changed to a linear scale if desired. In the View
controls (Figure 9-7), click
Logarithmic to access
the x-axis scale options menu. With a linear scale
selected, frequency is constant, but the width of
each octave along the x-axis is different. With a
logarithmic scale selected, octaves are displayed
with a constant width, but frequency is displayed
logarithmically within each octave.
Axes display
The Axes control (Figure 9-7) sets the opacity of
the grid displayed in the graph, from 100% (fully
visible) down to 0% (fully hidden).
Pausing the display
The Pause button in the upper right corner of the
View section (Figure 9-7) allows you to freeze the
display at any time. To resume, click the button
again.
Horizontal controls (frequency axis)
The Horizontal controls (Figure 9-7) configure the
value range of the x-axis (frequency). Click and
drag the values up or down to set them, or double-
click to return to the default value.
There are two modes for the controls: Zoom/Offset
and Min/Max . To change the mode, use the
Horizontal control menu (Figure 9-9).
Figure 9-9: Horizontal control menu
In Zoom/Offset mode, Zoom sets the display zoom
from 1x to 100x, where the number represents the
zoom factor relative to the entire frequency range.
For example, when the horizontal zoom value is 1x,
the entire frequency range from 10 to 24000 Hertz
is displayed; when the horizontal zoom value is 2x,
one half of the entire frequency range is displayed.
Pos determines which frequency is displayed at the
center of the graph.
Pause button
Display options
Black Blue Green Yellow Orange Red
Silence Full scale