McIntosh XRT29 - Manual (Page 4)

4
McIntosh Acoustic Engineers have refined the line source
Column Loudspeaker concept to provide superior quality
midrange and high frequency sound reproduction.
The High Fre-
quency Section
utilizes a patented
Column Design
1
with multiple four
inch Midrange
LD/HP
2 Magnetic
Circuit Design
Drivers and one
inch soft dome
Tweeters. Refer to figure 1. Since the audio power fed to a
column is distributed among all the drivers, each driver
does not have to work as hard, resulting in greater power
handling capability and a dramatic reduction in distortion.
The Sound Waves from the Column produce a Cylindrical
Wave Front with a stable symmetrical horizontal sound
dispersion to minimize undesirable floor and ceiling re-
flections
that could
detract from
a stable
sound im-
age. Refer
to figure 2.
In the illus-
tration the
Loud-
speaker on the left side produces a Cylindrical Wave Front
and the Loudspeaker on the right side produces a conven-
tional Spherical Wave Front.
The Midrange Drivers incorporate McIntosh’s Patented
LD/HP 2 Magnetic Circuit Design with shielding to greatly
reduce any external mag-
netic field. Extensive inves-
tigating and testing resulted
in a new design concept
which utilizes a pair of alu-
minum shorting sleeves in
the magnetic circuit. Refer
to figure 3. The sleeves vir-
tually eliminate the nega-
tive influence of the fluctu-
ating voice coil field on the
permanent magnet field.
This results in lower distortion due to more linear mag-
Introduction
Figure 4
Figure 2
Figure 1
Figure 5
netic flux in the voice coil gap. Refer to figure 4. Addi-
tional benefits are
less volume com-
pression due to im-
proved heat transfer
through the sleeves
and a cooler operat-
ing voice coil. Both
measurements, as
well as critical lis-
tening, reveal ten
times less distortion
than previous de-
signs. A good example of this low distortion is incredible
smoothness and clarity in the reproduction of the human
voice.
The Crossover Network used in the XRT29 Loud-
speaker System is designed to ensure an even frequency
response over its
audible range. The
Crossover Network
utilizes both Second
and Third Order
Crossover Designs.
Refer to figure 5. It
also uses Capacitors
and Inductors with
high current capac-
ity. The Capacitors
used include low
loss (ESR) Polypro-
pylene and Mylar
types. The Cross-
over Network uti-
lize self resetting
high current Poly-Switches to provide an extra measure of
protection.
The enclosure is an important part of the XRT29 Loud-
speaker System. The High Frequency Column utilizes a
massive extruded aluminum enclosure that houses the 30
four inch Midrange and 25 one inch Tweeter Drivers. Re-
fer to figure 6. It
also has multiple
front to back in-
ternal braces to
form a dampened
rigid Column
Structure. The
Column’s small footprint allows for a variety of different
placements in a room.
Figure 3
LD/HP
Conventional
1 COLUMN Pat. No. 4,267,405 2 LD/HP Pat. No. 5,151,943
Figure 6