Detailed instructions for use are in the User's Guide.
[. . . ] 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. [. . . ] 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.
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 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 wider plot on each chart is the horizontal polar () and the narrower plot is the vertical polar ( ).
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.
The axial directivity factor R (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.
Figure 2. Cobreflex IIB Directivity Factor and Directivity Index vs. Frequency
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