© Telex Communications, Inc. 02/2001
Part Number 38109-857 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 IIB, 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
Figure 1.
Cobreflex IIB Polar Response
Figure 2.
Cobreflex IIB Beamwidth vs. Frequency
Figure 3.
Cobreflex IIB Directivity Factor
and Directivity Index vs.Frequency
distance. The horn was suspended freely with no baffle. The polar
plots shown in Figure 1 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 IIB’s 6-dB-down total included beamwidth
angle is shown in Figure 2 for each one-third-octave center
frequency.
Directivity
The axial directivity factor R
θ
(formerly Q) of the Cobreflex IIB 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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