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Author:Admin     Click:940     Time:2018-01-03 11:20:00

PH-118B is a very compact subwoofer housing a single 18-inch driver, the frontal of the cabinet is about the same size as the 18-inch unit. (See Figure 137)

The enclosure
The enclosure is of phase inverted (or vented) design. The advantage of this design is that sound wave radiated from the rear of the speaker be in phase with the sound wave radiated from the speaker front by proper phase adjustment after passing through the vent. The vent itself functions as an additional radiator is this case, and its radiation can add constructively to that of the speaker over certain frequencies. It requires less speaker excursion and therefore reduced amplitude distortion for a given acoustic output in the lowest portion of its usable bandwidth. This effect is most noticeable for frequencies in the neighborhood of the system lower cutoff frequency.

For the same lower cutoff frequency, the enclosure can be made smaller and due to this reason, the air within the enclosure acting as an air cushion at very strong transient signals. (See Figure 138)

Figure 138
The component
PH-118B housed a single L18/100/11Z 18-inch cone type driver
Single L18/100/11Z drivers are used in PH-118B and developed by iBO specifically for horn loading
Frame is die cast alloy
The cone is a special formula of pulp and glass fiber. The depth of the cone is rather shallower with reinforcement ribs for better reproduction of low-frequency
Surround and spider are stiffer to increase the mechanical stiffness
The cone is treated with inflammation resistant agent
The diameter of the voice coil is 4-inch edge wound with flat copper wire on a Kapton former.
The magnet is made from y30 high flux strontium ferrite weights 10.75kgs. (See Figure 139 and 140).

Figure 139

The Crossover Network
Normally there is no built-in passive crossover network is a subwoofer or perhaps only a built-in low pass filter but even a low pass filter could cause phase problem and there is insertion loss. For these reasons, the PH-118B has no built-in passive crossover network nor low pass filter. It is recommended that all PH series speakers should be used in conjunction with external speaker processor with delay and equalization functions such as iBO D-24 (2in 4out) or D-48 (4in 8out) digital speaker processor.

Applications and Technical Specifications
PH-118B can be used in conjunction with any of the PH-110, PH-112 and PH-115 as the main speaker of small to medium sound reinforcement system for assembly hall, multi-function hall or other audio visual activities or used as stage monitor or as auxiliary speaker for a large sound reinforcement system.

Technical Specifications and diagrams (See below)

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