JBL K2 S9900, Product Commentaries And User Manual

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Project K2 S9900
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CHAPTER 2
The Project K2 S9900 Loudspeaker – a Triumph in Acoustics and
Technology
The following sections describe the primary features and components of the
Project K2 S9900 loudspeaker system.
The basic system configuration is what has been referred to historically as an
augmented two-way. In the 1950s and 1960s, JBL engineers primarily built
two-way systems with a 12- or 15-inch (300mm or 380mm) woofer crossed over
to a large-format compression driver/horn combination. Some of the systems
would be “augmented” by a UHF device, usually the 075 ring radiator which
would operate above 8kHz. These systems would have only a single crossover
point in the middle of the audio range, to minimize any sonic degradation
caused by the dividing network. The K2 S9900 has a single midrange crossover
at 900Hz, blending one 1500AL-1 woofer to the 476Mg compression driver and
horn combination. The 045Be-1 UHF driver is brought in at 15kHz to cover 2
octaves of ultrasonic frequencies. Above 900Hz, the HF compression driver and
horn combination operates unassisted, all the way to 20kHz (Fig. 1).
Figure 1. On-axis response of the K2 S9900 system and of each of the
transducers through its crossover network (2.83V @ 1m).
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