Nova HDC 84, User Manual

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Drive Modules may be included in Module Groups, which use the Parameter Overlay feature in the
HDC48 to achieve trouble-free Grouping in the System Engineer application.
The Presets in the HDC48 are Drive-Module centric, and are used to configure individual Drive
Modules rather than the whole device.
Importantly, Drive Modules move the focus away from the processing device, and onto the
loudspeaker systems.
A Drive Module Preset may be broken apart into Components, allowing any output to be used for
any component within a Drive Module Preset (i.e. any driver in a loudspeaker subsystem).
See Overview of Modules
Overlays
When the HDC is used in Modules view in System Engineer, this allows the modules to be grouped
into
Overlay G roups . These groups allow various Input (master) parameters to be adjusted in all
modules in that group, whist maintaining independent parameter values across each group. This is
achieved in the device by combining the parameters for all the layers for a given section (Gain Delay,
EQ etc.). When an Overlay parameter is active, the Overlay indicator will become illuminated. The
combined Gain or Delay etc. associated with a given section is shown on the module panel in System
Engineer, within square brackets [ ] under the Delay and Gain for each input channel. The combined
EQ curve is shown in an olive colour. The Input Mute button in System Engineer will flash if an
overlay mute is active. On the device, the presence of an active overlay is generally indicated by
square brackets “[]” after the parameter value on the display. A n input overlay mute is indicated on
the mute/clip indicator for that channel flashing. Note that overlay parameters cannot be adjusted
on the HDC device itself; these can only be controlled by the System Engineer application. However,
overlay parameters may be removed on the device
– see Overlay Flush . Note that overlays are not
stored in presets or snapshots or carried in settings files.
LIR Linear Phase Crossover Filtering
The HDC also includes a new type of crossover filtering “Linea r Impulse Response” (LIR) cros sover
filtering, which results in a Linear Phase crossover that has a constant delay regardless of frequency
(unlike other types of crossover which delay different frequencies to a different extent, thus
smearing the arrival time). The LIR crossover can thus be described as having a flat Group Delay
response, and thus entirely free of Group Delay Distortion.
The shape of the LIR crossover filter is quite similar to a 4
th
order or 24dB/Oct Linkwitz-Riley filter,
and maintains zero phase difference between the adjacent bands across the crossover region to
keep the polar response rock steady.
FIR Linear Phase Equalisation
The Input High-Shelf Equalisers use Finite Impulse Response (FIR) filtering to produce Linear Phase
equalisation; that is all frequencies are delayed by the same amount, perfectly preserving the
transient response. This can also be important in applications where different amounts of EQ are
applied to different parts of a speaker cluster, such as to add 'Throw' EQ boost so that parts of
cluster which are throwing further can have HF absorption correction added. If this EQ is not linear
phase, then the zones where the speakers combine may suffer frequency response anomalies.