MartinLogan EFX Manuel De L'utilisateur page 25

Controlled Horizontal Dispersion
Your EFX's launch a 30 degree horizontal dispersion pattern. This
horizontal dispersion field gives a choice of good seats for the per-
formance while minimizing interactions with side walls (see figure
16). 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 adjust-
ments can result in noticeable sonic improvements.
Controlled Vertical Dispersion
As you can see from the illustrations, your EFX speakers project
a controlled dispersion pattern (see figure 17). Each EFX is a 28
inch line source. This vertical dispersion profile minimizes inter-
actions with the floor and the ceiling.
Figure 12– 13. 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 14–15. 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 16–17. A controlled 30 degree cylindri-
cal wave-front, a MartinLogan exclusive, offers
optimal sound distribution with minimal room
interaction. The result is solid imaging with a
wide listening area.
d
IspersIon
Three Major Types of Dispersion
It is a known fact that as the sound wave becomes progres-
sively 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 exhaus-
tive testing of many different methods, we conceived an
elegantly simple, yet intensely hand crafted process. By curving
the radiating surface, we create the effect of a horizontal arc.
This allows the engineers at MartinLogan to control the high fre-
quency dispersion pattern of our transducers.
I
nteraCtIons
Dispersion Interactions 25