Electro-Voice COBREFLEX IIB Specifications

General Product Description

The Cobreflex IIB is an exponentially flared, reflex design
for use in public address, paging, and voice warning systems.

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

The patented (patent # 2,751,996) folded design features
two separate air columns in a single assembly that virtually
eliminates high-frequency phase cancellation present in
re-entrant designs.

The 80-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 IIB is constructed from a high-impact
acrylonitrile butadiene styrene (ABS) with an ultraviolet
inhibiting grey paint 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 reflex type featuring two separate
air columns within the single assembly. It shall produce a
horizontal beamwidth of 80-degrees and a vertical
beamwidth of 60-degrees at 2 kHz. In addition, it shall
provide useful acoustic loading at all frequencies above 250
Hz.

The horn shall be constructed from a high impact acrylonitrile
butadiene styrene (ABS) and finished with an ultraviolet
inhibiting grey paint.

Cobreflex IIB

Folded

Sectoral Horn

COMMERCIAL

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 1.91 cm (0.75 in.) diameter
and shall be provided with a 1 3/8"-18 thread for the mounting
of a compression driver. The horn shall be 23.5 cm (9.3 in.)
high, 47.0 cm (18.5 in.) wide and 26.0 cm (10.3 in.) deep. It
shall weigh no more than 2.3 kg (5.1 lb).

The horn shall be the Cobreflex 11B reflex horn.

Specifications:

Horizontal Beamwidth:

80° @ 2 kHz (see Figure 2)

Vertical Beamwidth:

60° @ 2 kHz (see Figure 2)

Directivity Factor Rθ (Q):

9.1 @ 2 kHz (see Figure 3)

Usable Low-Frequency Limit:

250 Hz

Construction:

High impact acrylonitrile butadiene styrene (ABS) with
ultraviolet light inhibiting grey paint finish. Positive-lock painted
steel U-bracket.

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"-18 thread.

Dimensions:

Height: .......................................................... 23.5 cm (9.3 in.)

Width: ......................................................... 47.0 cm (18.5 in.)

Depth: ......................................................... 26.0 cm (10.3 in.)

Net Weight: .............................................................. 2.3 kg (5.1 lb)

Shipping Weight:..................................................... 3.0 kg (6.7 lb)

Recommended Horns:

ID30C-8 7110XC ID30C-16 1824S

ID30CT 1828R ID60C-8 1828T

ID60C-16 1829 ID60T ID75

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 one­third-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 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 Rθ (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.

Cobreflex IIB Polar Response

Figure 1.

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 38109-857 Rev A

Cobreflex IIB Beamwidth vs. Frequency

Figure 2.

Figure 3.

Cobreflex IIB Directivity Factor

and Directivity Index vs.Frequency

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.