The Filter Panel provides controls for the Speaker Type, Bass Management Cutoff and filters for each of nine channels, which by default are titled Left, Right, Centre, SL, SR, SBL, SBR, Sub and Aux. Channels can be selected from the keyboard using Alt+number, 1 for the Left channel, 2 for the right etc. The text on the channel's tab is black if the channel has measurement data, grey if not. Above the channel selection tabs are buttons to set the Target Level and to control the process of locating peaks and assigning and optimising filters to correct them. The currently selected equaliser is shown at the top of the list of filters.
The channel names can be changed by right-clicking on the channel's tab,
the new name is remembered for the next startup. There is an option to reset
all the channel names to their defaults (Left, Right etc). The right-click menu
also has a shortcut to the dialog for viewing/editing the measurement notes (for more
information see the View menu entry).
Channels for which measurement notes have been entered show the notes icon
on the tab. The notes themselves appear in
the tooltip text for the corresponding tab.
The
button is used to measure the SPL the current channel produces
when fed with a pink noise calibration signal at the
Measurement Level. The resulting SPL
then becomes the target level for the channel for subsequent
filter adjustments. When the button is pressed a reminder window is
displayed confirming the connections required, when OK is selected the
Wizard first checks that the level from the SPL meter is suitably low when
there is no signal, then generates the calibration signal and measures its
level. The Target Level control
in the Filter Panel is then set to the measured level.
The Target Level that has been measured for a channel remains valid as long as the SPL Meter is not moved and the AV processor volume, input level and measurement level are not altered. If any of these have changed, or if the channel is being re-measured with additional EQ filters or modified EQ filter settings, repeat the Target Level setting for the channel before making further measurements.
Search for peaks in the measured data for this channel within the
frequency range set by the controls below the button. Results are shown
to the left of the graph, sorted by the amplitude of the peaks
relative to the channel's target level. The peak data can be hidden/revealed
via an item in the Graph menu or by using
the corresponding shortcut keys.
Assigns PK filters to correct peaks found by the Find Peaks function.
Filters are assigned in order until either all peaks have been assigned a
filter or all available filters have been used. Only filters with "Control"
set to "Automatic" are used.
Iteratively adjust the gain and Q settings of the PK filters to obtain
the best match to the shape of the peaks and hence the flattest corrected
response. The optimiser tries to match the shape over a region either side
of each peak's center whose boundaries are determined by the characteristics
of the peak and the nature of the frequency response nearby. The matching of
filter to peak is easiest to see when the
Invert Filters box is selected.
This button adjusts the gains of all Automatic PK filters to bring the
response at their centre frequencies to the target level. Q is not altered.
The main use for this is to readjust gains after making some manual
adjustments to the filter settings.
The Speaker Type for each channel can be set to "Bass Limited" (often
referred to as "Small"), "Full Range" (often referred to as "Large"),
"Subwoofer" (strictly speaking only applicable for the Sub channel) and "None".
The setting is remembered for the next startup.
The Target Response shown on the Graph Panel reflects the Speaker Type, with a 12dB/octave high pass shape for Bass Limited speakers, flat for Full Range and a 24dB/octave low pass shape for Subwoofers.
Bass Limited speakers and the subwoofer have an associated Bass Management
Cutoff frequency. The default is 80Hz, frequencies from 30Hz to 150Hz in 10Hz
steps are allowed. The setting is remembered for the next startup.
The Target Level for a channel is the SPL the channel's speaker would
ideally generate when fed a signal at the
Measurement Level. This level is
used to offset the Target Response correspondingly. The Wizard
sets the Target Level for
each channel, though it can be manually adjusted if required.
The Trace Offset control for each channel allows the position of the channel's frequency
response traces to be shifted. This only affects the position of the trace on the graph, not the
actual data values. To change the data values for a trace by the offset amount (which is in dB),
use the Add to Data button. Note that re-generating the frequency response from the
impulse response using Apply Windows will cause the levels to revert to their original values,
to re-scale the impulse response for a desired peak SPL figure in the frequency response use the
Scale Impulse Response controls in the Impulse Response
Controls graph group.
Each filter has:
The DSP1124P mode has an additional display showing frequency in the form
in which is must be entered on that unit, i.e. as a one-third octave centre
and a fine adjustment which ranges from -9 to +10.
The Filters and Filters+Target traces in the graph area update as filter controls are adjusted.