Concept ce m schematic

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information

the pleats open and close varies
directly with the frequency of the audio
signal. As the pleats narrow, air is
squeezed out, and this air movement
generates the sound. The Heil
Air-Motion Transformer, like other
loudspeakers, is a transducer - that is
it converts" or "transduces" energy
from one form to another (from
electrical to acoustic). It is also called a
transformer, because it produces
air-motion 5.8 times greater than its
own movement. This transformation
ratio" results in extraordinarily high
efficiency, and the extremely
lightweight diaphragm gives the
CONCEPT air-motion transformer
near-perfect transient response.

The aluminum conducting strips
cover over 50% of the actual radiating
surface of the Heil, resulting in an
evenly applied driving force totally
within the magnetic field, as well as
high power-handling capability. The
audible benefit of this is very wide
dynamic range with exceptional
linearity, hence the designation
Constant Energy. Even the best
conventional tweeters are actually
driven over a small fraction of their
radiating area, and inevitably exhibit
phase distortion in addition to poor
linearity. Distortion in the Constant
Energy Heil driver is quite low- so low,
in fact; that it approaches the excellent
performance of top amplifiers.

~ Another advantage of the
ingenious Constant Energy air-motion
transformer is that it can achieve its
great dynamic range without
sacrificing the small radiating area

. necessary for good dispersion and

accurate stereogjmaging. In addition,
the CE-Monitors Constant Energy
driver is a bipolar radiator, with
significant amounts of energy
dispersed laterally and vertically as
well. We engineered the CONCEPT
CE-quitor enclosure to take full
advantage of this wide, 120° horizontal
radiation pattern. '

Low-Frequency Driver And
Passive Radiator

Frequencies below 1300 Hz are
handled by a 12-inch woofer and
reinforced by a 141/2-inch mass-loaded
passive radiator at the lowest octaves.
The woofer incorporates a 2-inch
copper voice coil. bonded with
high-temperature epoxy on a precision
aluminum form. The woofer with its
powerful magnet assembly is
constructed with a die-cast aluminum
frame and a special double surround
to minimize uncontrolled resonances
inherent in stamped-basket speakers.
It assures long-term adherence to the
close CONCEPT tolerances.

The CONCEPT CE-Monitor utilizes
a 141/2 inch passive radiator to achieve
the profound low bass normaily
associated with the finest acoustic
suspension designs and the high
efficiency typical of vented or ported
enclosures. Careful design eliminates
both back-wave coloration and
fatiguing resonances. The passive
radiator is specifically calibrated to the
back wave of the woofer to reinforce
low frequency output below 100 Hz

and maintain efficiency. The passive
driver itself is a low-resonance styrene
foam laminated to a damping skin,

and it is also mounted in a die-cast
aluminum frame. Bass response of the
CONCEPT CE-Monitor is essentially
flat down to well below 30 Hz.

Crossover Network

Optimal blending of the Constant
Energy Heil driver with the low-freq-
uency driver is achieved by a 3-pole
crossover network that rolls off the
response of the Heil driver at an
unusually steep 18 dB/octave below
1300 Hz. The response of the 12-inch
woofer is more gently rolled off at
6 dB/octave above that frequency.
These slopes are calculated to permit
constant energy response and
maintain the drivers in perfect phase.

The precision elements in the 18
dB/octave portion of the crossover
consist of two high-voltage capacitors
for long life, and an air-core coil to
avoid saturation losses. The
6 dB/octave portion utilizes both an
air-core coil and a high-density
iron-core choke. The high-frequency

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