Creating crossovers
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If S21 arrays with LF beams are used in a system design, it will be necessary to create a crossover to determine which frequencies should be handled by which arrays.
Follow these steps to create a crossover in Plan. The example below is using 100Hz as the example crossover frequency:
Set Up Your Beams
Open your project in Plan.
Navigate to your main array and create a Coverage Beam.
From the target response list, select a high-pass filter at the desired level and crossover frequency (e.g., Low-shelf 12dB Crossover HP 100 Hz).
Click Optimize to create the beam
Add an LF Coverage Beam
Create a Low-Frequency (LF) Coverage Beam—this beam type is available for S21 arrays.
Select the corresponding low-pass target curve (e.g., Low-shelf 12db Crossover LP 100Hz).
Click Optimize to create the beam.
Fine-Tuning the Crossover
Enable Simulation mode using the toggle at the top of the viewport.
Place a probe in the venue at the point you would like to create the crossover, and open the Spectrum Panel.
Ensure the main beam and the LF beam being crossed-over are both unmuted in order to see their individual frequency contributions. Mute all other beams in the project.
Adjust the gain of the LF beam in the Tuning Panel to match levels.
Apply delay adjustments to align the beams in phase at the crossover frequency.
Verify that both beams match precisely at 100 Hz to achieve a smooth crossover.
When designing crossovers for LF Coverage Beams, aligning phase response curves can become challenging, as making visual comparisons across multiple beams is often difficult when beams have different arrival times.
To assist with this, HOLOPLOT Plan includes an auto-delay feature which is a visual aid that virtually subtracts the arrival time contribution of the slowest beam (as a linear phase) from the visualisation of all phase response curves in the plot.
The auto-delay value is determined automatically but can be manually overridden by the user at any time, as it has no effect on the beam's DSP or signal path.
Below are the images of the Target Response curves which can be found in the Target Response dropdown when creating a the Coverage Beam. The titles of the curves in the graph legend correspond to the titles of the curves in the list.
