JBL DD66000CH-EVEREST II [DD66000CH], Руководство пользователя

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Project Everest DD66000
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CHAPTER 2
The Project Everest DD66000 Loudspeaker – a Triumph in Acoustics and
Technology
The following sections describe the primary features and components of the
Project Everest DD66000 loudspeaker system.
The basic system configuration is what JBL historically has referred to as an
augmented two-way. In the 1950s and 1960s, JBL primarily built two-way
systems with a 12- or 15-inch (305mm 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 DD66000 has a single midrange crossover at 700Hz,
blending one 1501AL woofer to the 476Be compression driver and horn
combination. The 045Be-1 UHF driver is brought in at 20kHz to cover an
octave and a half of ultrasonic frequencies. A second 1501AL operates in the
bass frequency range from below 30Hz to around 150Hz, where it is rolled off
at a gradual 6dB/octave. The first-order slope ensures proper amplitude and
phase summing between the two woofers over their total operating range. Both
woofers operate below 150Hz, but only one of them extends up to the 700Hz
crossover point. This is done to achieve proper directivity control throughout
the entire woofer operating range, while delivering powerful and extended
low-frequency performance. Above 700Hz, the HF compression driver and
horn combination operates unassisted, all the way to 20kHz (Fig. 1).
Figure 1 – On-axis response of the DD66000 system and of each of the
transducers through its crossover network (2.83V @ 1m)