© Telex Communications, Inc. 02/2001
Part Number 38109-858 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.
Polar Response
The directional characteristics of the Cobreflex III, with driver
attached, were measured by running a set of polar responses, in a
large anechoic chamber, at each one-third-octave center frequency.
The test signal was one-third-octave pseudorandom 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 apexes
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
Figure 1.
Cobreflex III Beamwidth vs. Frequency
Figure 2.
Cobreflex IIB Polar Response
Figure 3.
Cobreflex III Directivity Factor
and Directivity Index vs. Frequency
plots shown in Figure 2 display the results of these 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 Cobreflex III’s 6-dB-down total included beamwidth
angle is shown in Figure 1 for each one-third-octave center
frequency.
Directivity
The axial directivity factor R
θ
(formerly Q) of the Cobreflex III horn
was computed at each one-third-octave center frequency from the
horizontal/vertical polars and is displayed in Figure 3.
USA
12000 Portland Ave South, Burnsville, MN 55337, Phone: 952-884-4051, FAX: 952-884-0043
Canada
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Switzerland
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Germany
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France
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Australia
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Hong Kong
Unit E & F, 21/F, Luk Hop Industrial Bldg., 8 Luk Hop St., San PO Kong, Kowloon, Hong Kong, Phone: 852-2351-3628, FAX: 852-2351-3329
Japan
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Singapore
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Mexico
Av. Parque Chapultepec #66-201, Col. EI. Parque Edo. Mex. 53390, Phone: (52) 5358-5434, FAX: (52) 5358-5588
UK
4, The Willows Centre, Willow Lane, Mitcham, Surrey CR4 4NX, UK, Phone: 44 181 640 9600, FAX: 44 181 646 7084
Africa, Mid-East
12000 Portland Ave South, Burnsville, MN 55337, Phone: 952-887-7424, FAX: 952-887-9212
Latin America
12000 Portland Ave South, Burnsville, MN 55337, Phone: 952-887-7491, FAX: 952-887-9212
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