W-118B is a subwoofer fitted with one 18-inch unit
For simpler functions in small venue where only a couple of speakers are required the full range speaker used may be need to extend its frequency response to 50HZ or even lower to cope with the functional requirement. Not in the case of speakers as part of an array. An array usually consists of many speakers, each individual speaker or a group of speakers serve for specific purpose. There is no need for any speaker or part of the array to cover the entire frequency range. The full range speaker need not extend down to very low frequency as it would be covered by subwoofers. Besides, the full range speakers in line array physical and acoustic limitations. As part of a line array, the w-118B is designed to handle to low end of the frequency response down to around 40HZ.
The enclosure of W-118B is of front horn loaded and rear closed design (See Figure59 ). One LF units are mounted on the bass horn that is near the opening of the horn to leave more space behind the horn so that the emclosure can be made smaller.
. The enclosure is made of 18mm (11-ply) birch plywood. All joints are ferron and mortise of Chinese tradition plus screws and adhesive to ensure the rigidity and durability.
Many domestic and imported speaker enclosures using medium density fibre (MDF) board to reduce cost, but MDF has a fatal weakness. It soften when moisten and loss its rigidity. IBO rather uses expensive birch plywood to build the enclosures to ensure its strength and rigidity no matter used indoor or outdoor, rain or fine. (See Figure60 )
The enclosure is heavily braced internally and a black powder-coated steel mesh grille protects the drivers from damage. The finishing is in black semi-matt textured environmental friendly paint. A rear connector plate fitted with two Neutrik Speaker NL4MP connectors for amplifiers and for loop-in and loop-out to additional enclosures (See Figur61e)
One L18/100/11Z LF cone type driver are used in W-118B, L18/100/11Z is 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 (See Figure62 )
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. (See Figure63)
The magnet is of Y 30 high flux strontium ferrite. The magnetic structure weights 10.75 Kgs.
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 W118B has no built-in passive crossover network nor low pass filter. It is recommended that all LA series speakers should be used in conjunction with external speaker processor with delay and equalization functions such as iBO D-26(2 in 6 out) digital speaker management unit.
Applications and Technical Specifications
W-118B is not design for use independently. It may be used inconjunction with W-3F, W-6F and/orW-8F to make up a 3-way or 4-way array sufficient to handle any large activities includinglarge discos,large touring, large stadiums and arenasand large theaters at all weather.
40 Hz ~ 170 KHz (± 3 dB )/ 30 Hz ~ 200 Hz(-10 dB)
103 dB(50 Hz~200 Hz)
1×18〞horn-loaded (4″voice coil)
CALCULATED OUTPUT (MAX)
131 dB SPL, 137 dB SPL peak
2×2 Neutrik NL4MP connectors
For Technical Specifications and Diagrams( see below)