Rane RPM 26 - Manual (Page 18)

Manual-18
Cancel if you lack the proper analysis tools.
Once in Advanced mode, more edit boxes appear allowing
precise control of each individual filter type, slope and
frequency. This allows Linkwitz-Riley (
LR), Butterworth
( BW) or Bessel filters with 12, 18 or 24 dB/Oct. slopes,
where applicable, and independent frequency settings for
each filter.
One can return from Advanced crossover mode to Simple
mode with the right mouse click menu, however, you must
return both the crossover filter types back to
LR-24
(Linkwitz-Riley 24 dB/Oct.) and the crossover frequency
points back to the same frequency value.
A 24 dB/Oct. (4 th order) Linkwitz-Riley filter is made up
of two cascaded 12 dB/Oct. (2nd order) Butterworth filters.
Therefore, there is no such thing as an 18 dB/Oct. (3rd order)
Linkwitz-Riley filter, since implementation of a 1½ order
Butterworth is unheard of—though someone may come up
with a 1½ wheeled bike! (There’s a good joke in there
somewhere…)
As with the Simple crossover mode, click and drag on the
graphed curve to alter the crossover frequency settings. In
advanced mode, however, each filter slope is independently
editable. You can still click directly on the intersection of two
curves to edit two filters’ settings simultaneously. Or click on
an individual curve’s downward slope to alter a single filter
by itself.
Note: It is wise to alter crossover frequencies directly on
the graph only when the outputs are muted or when the RPM
26 is not connected to amplifiers and speakers. This avoids
the potential catastrophe of slipping with the mouse or
reaching again for your latté and accidentally clicking the
mouse!
SUMMING AND I/O ROUTING
Some DSP Programs provide simple Input
Summing that is generally accompanied by
I/O Routing. The circled “plus” sign between
the two Input Blocks indicates that summing
is supported. A schematic drawing of a three
position switch with
A, B and + markings
indicates that I/O Routing is available for the
given output.
The Input summing simply adds the two
input audio signals together. For example, if
both inputs are in phase and each is 1 volt
RMS, the simple sum of the two would be, all
you math whizzes out there, 2 volts. Note that
this sends more signal to the Output Block processing which
may require additional Trim at the Outputs or Inputs. Be
especially aware of the amount of parametric EQ boost used
in summed outputs, since too much may result in digital
clipping.
Many DSP Programs also support user switchable I/O
routing indicated by a switch schematic symbol in the
simplified graphic or in the Device Edit screen. This allows
each output to be fed from either
Input A, Input B or the
simple sum of Input A+B. This functionality provides simple
and convenient room switching for ballroom applications
where the input source can be changed through a simple
contact closure. It also can provide a quick mono source for
balcony or cry rooms or, when used in conjunction with the
output PEQ, can provide an effortless subwoofer output
useful in many applications.
Simply double-click on the circular A, B or + switch
terminal to move the switch’s output (i.e., common) to the
desired Input.