Installation
As shipped, the “U” bracket is in position for vertical mounting. For horizontal
dispersion, (or for mounts where the bracket mounting holes must be
vertical), move bracket to the rear mounting position. The horn can be
mounted in a variety of horizontal and vertical configurations by using
adjustments of the swivel connections (bracket to horn).
Polar Response
The directional characteristics of the 848AT, with driver attached, were
measured by running a set of horizontal/vertical polar responses in a large
anechoic chamber at each one-third-octave center frequency.The test signal
was one-third-octave, pseudo-random pink noise centered at the indicated
frequencies. The measurement microphone was placed 6.1 m (20 ft) from
the horn mouth, while rotation was about the waveguide geometric apexes.
These axes of rotation are quite close to the apparent (acoustic) apexes
across the frequency range of measurement. Errors attributable to the slight
differences between the geometric and acoustic apexes are reduced to an
inconsequential level by the relatively long, 20-foot measuring distance.
The horn was suspended freely with no baffle. The polar plots shown in
Figure 1 display the results of those tests. The center frequency is noted on
each plot. The wider plot on each chart is the horizontal polar (-) and the
narrower plot is the vertical polar (---).
Beamwidth
A plot of the 848AT 6 dB-down total included beamwidth angle is shown in
Figure 2 for each one-third-octave center frequency.
Frequency Response
Figure 3 shows the axial frequency response of the 848AT. It was measured
at a distance of 1 meter, using a swept sine wave.
Transformer
A transformer is installed in the driver housing.Power taps for the transformer
are listed in Table 1.
Low-Frequency Driver Protection
When frequencies below the low-frequency cutoff for the horn assembly
are fed to the driver, excessive current may be drawn by the driver. For
protection of the driver, amplifier and transformer, capacitor(s) in series
with driver or transformer primary is recommended. Table 1 indicates
recommended values. The values shown are for 200 Hz. Values for other
frequencies can be determined by using the formula:
C = [C200 x 200 ]
C200 = Values shown in the following table
Figure 1
848AT Polar Response
Figure 2
848AT Beamwidth vs. Frequency
Figure 3
848AT Frequency Response
(1 watt at 1 meter)
f f = New Frequency
.seniLtloV-07seniLtloV-07
rewoPecnadepmIecnaticapaCecnadepmIecnaticapaC
W036615
fm
--
W513332
fm
--
W85261
fm
--
W405215.0
fm
6515
fm
W2- - 2132
fm
W1- - 5261
fm
W2/1- - 05215.
fm
Table 1. Series Protection Capacitors for 200 Hz and Below
© Telex Communications, Inc. 02/2001
Part Number 38109-839 Rev A
U.S.A. and Canada only.
For customer orders, contact the Customer Service department at
800/392 3497 Fax: 800/955 6831
For warranty repair or service information, contact the Service
Repair department at 800/685 2606
For technical assistance, contact Technical Support at 866/78 AUDIO
Please refer to the Engineering Data Sheet for warranty information.
Specifications subject to change without notice.
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