MACKIE HD1521 - Manual (Page 7)

Placement
WARNING: Installation should only be done by
an experienced technician. Improper instal-
lation may result in damage to the equip-
ment, injury or death. Make sure that the loudspeaker
is installed in a stable and secure way in order to avoid
any conditions that may be dangerous for persons or
structures.
The HD1521 speaker is designed to sit on the floor
or stage. It may also be pole-mounted via the built-in
socket on the bottom of the cabinet. Be sure the pole
is capable of supporting the weight of the HD1521. The
HD1521 may also be flown horizontally or vertically via
its 12 integrated fly points.
Check to make sure that the support surface (e.g.,
floor, etc.) has the necessary mechanical characteristics
to support the weight of the loudspeaker(s).
When pole-mounting loudspeakers, be sure that they
are stabilized and secured from falling over or being
accidentally pushed over. Failure to follow these precau-
tions may result in damage to the equipment, personal
injury, or death.
You can create a horizontal array by placing the cabi-
nets side-by-side. However, you should have a good un-
derstanding of the relationship between the splay angle
(the angle between the facing sides of the cabinets),
the on-axis power, and frequency cancellation effects
between cabinets.
When two cabinets are positioned vertically side-
by-side, the actual splay angle is 20º (determined by
a 10º angle on each cabinet side). As the splay angle
increases toward the angle of horizontal coverage (80º
for the HD1521), the on-axis power decreases, but the
frequency response becomes smoother as the comb-fil-
tering effects (caused by the interaction in the area of
double-coverage) decrease.
As with any powered components, protect them from
moisture. Avoid installing the loudspeaker in places
exposed to harsh weather conditions. If you are setting
them up outdoors, make sure they are under cover if you
expect rain.
Room Acoustics
The HD1521 loudspeakers are designed to sound neu-
tral; that is, to reproduce the input signal as accurately
as possible.
Room acoustics play a crucial role in the overall per-
formance of a sound system. Here are some additional
placement tips to help overcome some typical room
problems that might arise:
• Avoid placing loudspeakers in the corners of
a room. Doing so increases the low frequency
output and can cause the sound to be muddy
and indistinct.
• Avoid placing loudspeakers against a wall. This,
too, increases the low frequency output, though
not as much as corner placement. However, this
is a good way to reinforce the low frequencies,
if so desired.
• Avoid placing the speakers directly on a hol-
low stage floor. A hollow stage can resonate at
certain frequencies, causing peaks and dips in
the frequency response of the room. It is better
to place the loudspeakers on a sturdy table
or stand designed to handle the weight of the
HD1521.
• Position the loudspeakers so the high-frequency
drivers are 2 to 4 feet above ear level for the au-
dience (make allowances for a standing/danc-
ing in the aisles audience). High frequencies
are highly directional and tend to be absorbed
much easier than lower frequencies. By provid-
ing direct line-of-sight from the loudspeakers to
the audience, you increase the overall bright-
ness and intelligibility of the sound system.
• Highly reverberant rooms, like many gymna-
siums and auditoriums, are a nightmare for
sound system intelligibility. Multiple reflections
off the hard walls, ceiling, and floor play havoc
with the sound. Depending on the situation,
you may be able to take some steps to minimize
the reflections, such as putting carpeting on
the floors, closing draperies to cover large glass
windows, or hanging tapestries or other materi-
als on the walls to absorb some of the sound.
However, in most cases, these remedies are not
possible or practical. So what do you do? Mak-
ing the sound system louder generally doesn’t
work because the reflections become louder,
too. The best approach is to provide as much di-
rect sound coverage to the audience as possi-
ble. The farther away you are from the speaker,
the more prominent will be the reflected sound.
Use more speakers strategically placed so they
are closer to the back of the audience. If the
distance between the front and back speakers
is more than about 100 feet, you should use a
delay processor to time-align the sound. (Since
sound travels about 1 foot per millisecond, it
takes about 1/10 of a second to travel 100 feet.)
Keep in mind that the Contour EQ is a great way to
compensate for some of these issues.

Owner’s Manual
Owner’
s Manual