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Directivity
The axial directivity factor R
was computed at each one-third-octave center frequency from
the horizontal/vertical polars. The graph in Figure 2 illustrates
this data over the range 500 Hz to 20 kHz. The axial frequency
response of the HP420 with a particular driver is in close
correspondence to that driver's power response above 500
Hz.
Figure 2: Directivity vesus Frequency
© Telex Communications, Inc. 02/2001
Part Number 38109-952 Rev A
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(formerly Q) of the HP420 horn
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Figure 1: Dimensions
Beamwidth
A plot of the HP420's 6-dB-down total included beamwidth
angle is shown in Figure 3 for each one-third-octave center
frequency. The horizontal beamwidth is maintained at 40°
(+20°, -10°) over the range of 650 Hz to 20 kHz. Vertical
beamwidth control occurs only above 2.2 kHz because of
the relatively short vertical dimension of the horn's mouth.
Figure 3: 6-dB-Down Beamwidth versus Frequency
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