4
McIntosh Acoustic Engineers have refined the line source
Column Loudspeaker concept to provide superior quality
midrange and high frequency sound reproduction in a full
range system.
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 hori-
zontal 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
Loudspeaker on the left side produces a Cylindrical Wave
Front and the Loudspeaker on the right side produces a
conventional Spherical Wave Front.
The Low Frequency Section of the System consists of
two 12 inch Woofers. They have a large magnet assembly
and long
cone ex-
cursions
with very
low levels
of har-
monic dis-
tortion and
frequency
response
down to
16Hz. Re-
fer to fig-
Introduction
Figure 5
Figure 2
Figure 1
Figure 6
Figure 3
ure 3. The Woofer also incor-
porates McIntosh’s Patented
LD/HP
2
Magnetic Circuit De-
sign with shielding to greatly
reduce any external magnetic
field. Extensive investigating
and testing resulted in a new
design concept which utilizes
a pair of aluminum shorting
sleeves in the magnetic cir-
cuit. Refer to figure 4. The sleeves virtually eliminate the
negative influence of the fluctuating voice coil field on the
permanent magnet
field. This results in
lower distortion due
to more linear mag-
netic flux in the
voice coil gap. Re-
fer to figure 5. Ad-
ditional benefits are
less volume com-
pression due to im-
proved heat transfer
through the sleeves and a cooler operating voice coil. Both
measurements, as well as critical listening, reveal ten times
less distortion than previous designs. A good example of
this low distortion is incredible smoothness and clarity in
the reproduction of the human voice.
The Crossover Networks used in the XRT30 Loud-
speaker Sys-
tem are de-
signed to en-
sure an even
frequency re-
sponse over
the entire au-
dible range.
The Low Fre-
quency Cross-
over Network
is a Third Or-
der design uti-
lizing Capaci-
tors and In-
ductors with
high current
capacity. Refer to figure 6. There are three different types
of low loss (DCR) Inductors in the network, each one cho-
sen not to exhibit any core saturation even at high power
Figure 4
LD/HP
Conventional
1
COLUMN Pat. No. 4,267,405
2
LD/HP Pat. No. 5,151,943
