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D
I
ISPERSION
Controlled Horizontal Dispersion
Your Purity's launch a 30 degree horizontal dispersion pat-
tern. This horizontal dispersion field gives a choice of good
seats for the performance while minimizing interactions with
side walls (see figure 12). Make sure both speakers stand
exactly at the same vertical angle, otherwise the image can
be skewed or poorly defined. The wave launch of both
speakers is extremely accurate in both the time and spectral
domain. Consequently, small refined adjustments can result
in noticeable sonic improvements.
Controlled Vertical Dispersion
As you can see from the illustrations, your Purity speakers
project a controlled dispersion pattern (see figure 13). Each
Purity is a 28 inch line source beginning 24 inches above
the base. This vertical dispersion profile minimizes interac-
tions with the floor and the ceiling.
Figure 8– 9. As can be seen here, point
source concepts invite a great deal of room
interaction. While delivering good frequency
response to a large listening audience, imaging
is consequently confused and blurred.
Figure 10–11. Even though they suffer from
"venetian blind" effect, angled multiple panel
speakers can deliver good imaging, but only
to specific spots in the listening area.
Figure 12–13. A controlled 30 degree cylin-
drical wave-front, a MartinLogan exclusive,
offers optimal sound distribution with minimal
room interaction. The result is solid imaging
with a wide listening area.
12
Dispersion Interactions
NTERACTIONS
Three Major Types of Dispersion
It is a known fact that as the sound wave becomes pro-
gressively smaller than the transducer producing it,
the dispersion of that wave becomes more and more
narrow, or directional. This fact occurs as long as the
transducer is a flat surface. Large flat panel speakers
exhibit venetian blind effects due to this phenomenon.
This is one reason why many manufacturers opt for small
drivers (i.e. tweeters and midrange) to approximate
what is known as a point source wave launch.
Historically, most attempts to achieve smooth dispersion
from large flat panel transducers resulted in trade-offs.
After exhaustive testing of many different methods, we
conceived an elegantly simple, yet intensely hand craft-
ed process. By curving the radiating surface, we create
the effect of a horizontal arc. This allows the engineers at
MartinLogan to control the high frequency dispersion pat-
tern of our transducers.
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