Extron Electronics DMP 128 User Guide - Manual (Page 82)

Virtual send Bus Mix Matrix
The DSP architecture contains a Virtual Send Bus mix matrix that connects the inputs and
virtual bus return signals to the virtual sends. There is an additional mix matrix to route
EXP input signals to the virtual sends.
The DSP Configurator main screen provides control of the virtual bus mix matrix, used
to set levels from input signals to the virtual sends. Each of the twelve mic/line and eight
virtual return inputs are connected to a mix-point for virtual bus A through H (and the
EXP inputs). Each mix-point is muted and set to 0.0 dB (unity gain) by default. In general,
mix levels are set relative to each other, achieving a desired blend of input signals at an
optimal level close to, but not exceeding 0 dBFS at the output volume level meter.
The virtual mix matrix contains a section (see figure 45 below) that allow the virtual
bus returns to be routed back to the virtual bus matrix for further processing using an
additional virtual bus processing block. To prevent feedback loops, a virtual channel is
prevented from being routed back to itself by eliminating the mix-point that would allow
that to occur.
In situations requiring extra processing, the virtual bus return output is routed back to the
virtual bus send mix matrix, which then routes the signal back to a processing signal chain
other than the one it was routed from.
Virtual Send Bus Mix-points
(from Mic/Line Inputs)
Virtual Send
Bus Mix Matrix
Virtual Send Bus Mix-points
(from Virtual Bus Returns)
EXP Inputs to Virtual Bus
Sends
a
b
c
Figure 45. virtual Bus mix matrix (EXP inputs 9-16 not shown)
DMP 128 • Software Control 76