Meyer Sound UMS-1P - Manuel (Page 7)

7
Introductory Concepts
The UMS-1P is used to extend the low
frequency response of a sound system,
complementing systems in a wide vari-
ety of applications in sound reinforce-
ment as well as music playback and
monitoring. Though it can be used with
all Meyer Sound products, it is the ideal
compliment to the UPM-1P self-powered
loudspeaker. Using the UMS-1P in a full-
range system is fairly straightforward
but the following concepts are impor-
tant to consider before installing a sys-
tem.
Room Loading
The placement of the UMS-1P in a room
or a space is critically important to the
response of the loudspeaker system.
The subwoofer's placement in the room
working with the geometric shape of the
space will affect a loudspeaker's fre-
quency response due to the longer
wavelengths of these lower bands inter-
acting with the walls, ceiling, and floor.
A UMS-1P or any subwoofer hung in the
air with no boundary conditions would
not add any additional SPL from room
loading, while a UMS-1P placed on a
floor (half-space loading) will gain
approximately 6 dB compared to its free
field response.
6 dB low frequency gain compared to
free field.
A UMS-1P placed on a floor and against
a wall (quarter-space loading) will gain
approximately 12 dB compared to its
free field response.
12 dB low frequency gain compared to
free field.
A UMS-1P placed on the floor in a cor-
ner (one-eighth space loading) will gain
approximately 18 dB compared to its
free field response.
18 dB low frequency gain compared to
free field.
SPL vs. Distance to Boundary
As we have seen in the previous illustra-
tions, the placement of a UMS-1P on a
floor or against a boundary significantly
changes the low frequency response
when compared to free field measure-
ment of the same loudspeaker.
The following graph represents the
approximate change in dB SPL for fre-
quencies under 125Hz of a single UMS-
1P as it is moved away from a boundary.
Some frequencies will be aided by this
rear reflection, while others will have
opposing phase, resulting in an approxi-
mate attenuation. The distance is based
on the distance in meters from the wall
behind the loudspeaker to the acoustical
center of the UMS-1P. All dB SPL mea-
surements are made with the micro-
phone on axis to the loudspeaker.
Distance to Boundary vs. dB SPL
below 125
To better understand the graph above,
imagine a UMS-1P with a wall behind it.
As you move the UMS-1P away from the
wall the graph above shows how the
response of the loudspeaker will change.
For example, if the UMS-1P is placed 1
meter from a wall and is measured on
axis to the loudspeaker, you will see a
-5 dB change in the low frequency as
illustrated by the dotted lines on the
graph.
APPLICATIONS
-8
-6
-4
-2
0
2
4
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Distance in meters between wall and acoustical center of speaker.
dB SPL relative to free-space response.
Amplifier Cooling System
The UMS-1P's amplifier employs a natur-
al convection cooling system. Always
allow for proper ventilation when using
the loudspeaker in tightly packed condi-
tions.
If the temperature of the heatsink reach-
es 85°C (185°F), the On/Temp. LED on
the rear panel turns from green (On) to
red (Temp.) and the limiter threshold is
lowered to a safe level to prevent the
system from overheating. Under high
temperature conditions the output level
is reduced 6 dB. When the heatsink tem-
perature decreases to 75°C (167°F), the
On/Temp. LED changes from red to green
and the limiter threshold returns to nor-
mal.
The heatsink can reach tem-
peratures of up to 185°F
(85°C) during normal opera-
tion. Use caution to avoid
injury due to the tremendous
heat.
You must have 4” of clear-
ance between the UMS-1P
and any wall surfaces for
proper convection cooling.
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