Unfortunately, optimization in one area usually results in trade-offs elsewhere. For example, spatial
performance (pattern control) can be optimized by very large horns, but the resulting enclosure’s utility will
be severely degraded.
The goal of the CSC Series was to optimize performance attributes in all areas without compromising
others. Specifically, the main goals were:
• unifying arrival times within and among the subsystems
• achieving broadband pattern control in the both the vertical and horizontal planes
• creating a modular system that’s easy to move, install, and aim
• setting a new standard in audio fidelity
Optimized Mid-Frequency Sub-System:
Achieving temporal coherence and spatial consistency
EAW has historically created true three-way cinema loudspeaker systems that use cone transducers
to reproduce the majority of the vocal region. This approach significantly reduces distortion resulting in more
natural sounding dialogue. But the additional LF section has typically created compromises in the temporal
and spatial domains.
In addition to the sonic difficulties associated with transitioning between subsystems in the heart of
the vocal band, two-way systems suffer from higher distortion in the lower portion of the compression
driver’s range. In the temporal domain, however, two-way systems excel where typical three-way systems
falter.
Unlike the relatively simple geometry of a compression driver’s diaphragm, there is a slight but
noticeable difference in the point of origin of a cone driver’s dustcap, cone, and surround. Particularly in the
upper midrange, these differences create a “smearing” of arrival times at the listener that degrades the clarity
and impact of mid-frequency sonic events: most notably voice reproduction. Because they are what the ear
hears first, early arrivals out of the passband can affect overall fidelity even though they are substantially
lower in level.
Traditionally, most manufacturers (including EAW) have asked the mid-frequency phase plug to fix
the arrival smear. But because this approach treated the symptom (inconsistent arrivals at the horn throat)
instead of attacking the disease (bad cone geometry),
it fails. In contrast, the CSC Series’ entire mid fre-
quency cone and phase plug assembly was designed
to solve this problem at the source.
The distance from a cone driver’s voice coil
to its dustcap is shorter than the distance from the
voice coil to either the cone or surround. Therefore,
the energy radiating from the dustcap most often
leads the energy from the rest of the system. Tradi-
tional phase plug designs have isolated this energy
and routed it through a longer path than that which
faces the energy from the cone or surround. In so
doing, the phase plug attempts to equalize the arrival
smear.
Conventional phase plug designs achieve this result by using a circular entrance and exit to
the phase plug – they simply convert the output from a point source into a ring radiator. This approach has
proven effective with high frequency compression drivers mostly because the simpler compression driver
diaphragm geometry and shorter high frequency wavelengths create significantly smaller arrival differences
that are less problematic to resolve. But because the wavelengths in the mid frequency passband are so much
greater, this ring radiator solution actually creates another more serious problem.
A ring radiator exhibits a more dramatic narrowing of beamwidth with increasing frequency than a
cone transducer. When the mid frequency device becomes a ring radiator, its directivity narrows too greatly
with increasing frequency to the point where it no longer fills the bell of the horn. This is a problem that
virtually all horn-loaded mid or midbass systems suffer from, including systems that are highly regarded in
the professional audio and cinema sound communities. As a result all of these systems exhibit acceptable
low/mid coupling, but the mid/high energy does not cover from box to box, leaving upper mid holes in the
frequency response on the seams of an array.
The CSC Series mid/phase plug assembly approaches the problem in a different way. It attacks the
Dustcap
Surround
Cone
Voice Coil
Traditional Mid Cone with Phase Plug, Side View Cutaway
Voice Coil to Surround = 6.3 inches
Voice Coil to Dustcap = 4.5 inches
Traditional Phase Plug Creates Ring Radiator
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