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Virtual Bus Returns
There are eight mono virtual bus return inputs, fed by the virtual bus sends. Channel
controls and processing blocks described in the sub-sections that follow are identical for
each virtual bus return channel.
The eight returns are divided into two similar paths. Channels A-D contain a feedback
suppression processing block in each channel. Channels E-H are identical to A-D except
there are no feedback processing blocks.
Virtual Bus Returns, A-D
The virtual bus is used when additional processing of an input signal is required. It is also
useful to apply identical filtering, dynamics processing, loudness compensation, or signal
gain/attenuation to multiple inputs.
Feedback Suppressor (FBS)
The Feedback Suppressor (FBS) is used when there is indication of feedback during
live operation. Dynamic filters automatically detect feedback on a live mic channel, and
engage a set of up to five fixed and 15 dynamic filters to counteract the frequency peaks
at the detected feedback frequency. Up to 15 separate filters may be employed at any
time. The 15 filters act in a FIFO, or first in, first out rotation. If all 15 filters are employed,
when an additional feedback frequency is detected it will overwrite the first detected
feedback frequency and so on.
To avoid a new feedback frequency overwriting a previously detected one, up to five of the
dynamic feedback frequencies can be placed into fixed filters. Once written into the fixed
filters, the feedback frequency can only be overwritten by the user manually writing a new
frequency to the filter.
The FBS dialog box has three tabs; Settings, Dynamic Filters and Fixed Filters.
Global settings and view options are controlled from the settings tab. Dynamic to fixed
filter allocations are handled from the dynamic filters tab. Filter parameters can be
modified from the Fixed Filters tab.
DMP128 • Software Control 65