Electro-Voice Cobreflex III Specifications

General Product Description

The Cobreflex III is a folded sectoral, wide-angle horn for
use in public address, paging, and voice warning systems.

This folded sectoral construction results in both compactness
and high efficiency when combined with appropriate
compression drivers.

The patented (patent #4.176.731) folded design features two
separate air columns in a single assembly that virtually
eliminates high-frequency phase cancellation present in
reentrant designs.

The 100-degree horizontal by 60-degree vertical dispersion
pattern is beneficial in many applications requiring a wide
coverage pattern. Furthermore, excellent loading is
maintained to a low-frequency cutoff of 250 Hz.

The Cobreflex III is constructed from a non-resonant glass
fibre reinforced polyester with a self-colored gray finish. A
serrated positive-lock “U” mounting bracket is provided for
maximum mounting flexibility and ease of installation.

Architects’ and Engineers’ Specifications

The horn shall be of the folded sectoral type featuring two
separate air columns within the single assembly. It shall
produce a horizontal beamwidth of 100 degrees and a
vertical beamwidth of 60 degrees at 2.0 kHz. In addition, it
shall provide useful acoustic loading at all frequencies above
250 Hz.

The horn shall be constructed from a non-resonant glass
fibre reinforced polyester and self-finished in an
ultraviolet-inhibiting gray.

Cobreflex III

Folded

Sectoral Horm

COMMERICAL

A serrated, positive-lock “U” mounting bracket shall be affixed
to the bell by self-locking nuts and shall provide orientation
adjustment in all three planes.

The horn shall possess a throat of 2.54-cm (1.00 in.) diameter
and shall be provided with a 1 3/8"-18 thread for the mounting
of a compression driver. The horn shall be 36.8 cm (14.5 in.)
high, 69.9 cm (27.5 in.) wide and 38.1 cm (15.0 in.) deep. It
shall weight no more than 3.2 kg (7.0 lb).

The horn shall be the Cobreflex III folded sectoral horn.

Specifications:

Horizontal Beamwidth:

100° @ 2 kHz (see Figure 2)

Vertical Beamwidth:

60° @ 2 kHz (see Figure 2)

Directivity Factor R

15.9 @ 2 kHz (see Figure 3)

Usable Low-Frequency Limit:

250 Hz

Construction:

Non-resonant glass-fibre reinforced polyester
compression molding with self-colored gray finish.
Positive-lock painted steel U-bracket.

(Q):

θ

Mechanical Construction of Driver:

Threaded metal throat insert to accommodate a screw-in
driver with a throat opening of 0.7-inch to 1.0-inch
diameter and a standard 1 3/8-inch thread.

Dimensions:

Height: .............................................. 36.8 cm (14.5 in.)

Width: ............................................... 69.2 cm (27.5 in.)

Depth: ............................................ 38.1.0 cm (15.0 in.)

Net Weight: ................................................... 3.2 kg (7.0 lb)

Shipping Weight: ....................................... 4.5 kg (10.0 lb)

Recommended Horns:

ID30C-8 7110XC ID30C-16 1824S

ID30CT 1828C ID60C-8 1828T

ID60C-16 1829 ID60CT 1829T

ID75

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

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 Rθ (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.

Cobreflex III Beamwidth vs. Frequency

Figure 1.

Figure 3.

Cobreflex III Directivity Factor

and Directivity Index vs. Frequency

USA 12000 Portland Ave South, Burnsville, MN 55337, Phone: [phone], FAX: [phone]
Canada 705 Progress Avenue, Unit 46,Scarborough, Ontario, Canada, M1H2X1,Phone: [phone], FAX: [phone]
Switzerland Keltenstrasse 11, CH-2563 IPSACH, Switzerland, Phone: [phone]. FAX: [phone]
Germany Hirschberger Ring 45, D94315, Straubing, Germany, Phone: [phone], FAX: [phone]
France Parc de Courcerin, Alle Lech Walesa, Lognes, 77185 Marne La Vallee, France, Phone: [phone], FAX: [phone]
Australia Unit 23, Block C, Slough Business Park, Slough Avenue, Silverwater, N.S.W. 2128, Australia, Phone: [phone], FAX: [phone]
Hong Kong Unit E & F, 21/F, Luk Hop Industrial Bldg., 8 Luk Hop St., San PO Kong, Kowloon, Hong Kong, Phone: [phone], FAX: [phone]
Japan 2-5-60 Izumi, Suginami-ku,Tokyo, Japan 168, Phone: [phone], FAX:[phone]
Singapore 3015A Ubi Rd 1, 05-10, Kampong Ubi Industrial Estate, Singapore 408705, Phone: [phone], FAX: [phone]
Mexico Av. Parque Chapultepec #66-201, Col. EI. Parque Edo. Mex. 53390, Phone: [phone], FAX: [phone]
UK 4, The Willows Centre, Willow Lane, Mitcham, Surrey CR4 4NX, UK, Phone: [phone], FAX: [phone]
Africa, Mid-East 12000 Portland Ave South, Burnsville, MN 55337, Phone: [phone], FAX: [phone]
Latin America 12000 Portland Ave South, Burnsville, MN 55337, Phone: [phone], FAX: [phone]

www.electrovoice.com • Telex Communications, Inc. • www.telex.com

© Telex Communications, Inc. 02/2001

Part Number 38109-858 Rev A

Cobreflex IIB Polar Response

Figure 2.

For customer orders, contact the Customer Service department at

For warranty repair or service information, contact the Service

For technical assistance, contact Technical Support at 866/78 AUDIO

Please refer to the Engineer ing Data Sheet for warranty information.

800/392-3497 Fax: [phone]

Repair department at 800/685-2606

Specifications subject to change without notice.

U.S.A. and Canada only.