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Step-down tuning of the PIM-151 can be
achieved by plugging one of
its
two vents,
which lowers tuning from 38 to 27 Hz. A foam
vent plug (part no. 71489) is available from the
Electro-Voice Service Department. If an appro-
priate low-frequency boost-and-cut equaliza-
tion is applied, the normal f3 of 45 Hz is reduced
to 32 Hz. It is suggested that the Electro-Voice
Dx34 digital processor be used to provide the
required
equalization.
The suggested equal-
ization is an underdamped second-order high-
pass filter tuned to 27 Hz with a Q of 2. This
provides a boost of 6 dB at the tuning frequency
and a 12-dB-per-octave roll-off below.
SUBPASSBAND SPEAKER PROTECTION
Below the enclosure tuning frequency, cone
excursion increases rapidly. Since acoustic
output is also falling rapidly, there is no utility in
driving the system with signals much below
tuning frequency. While such signals may be in
the program material, they are often extrane-
ous, such as a dropped
microphone.
The step-
down equalization described in the Step-Down
section provides the required protection. If the
step-down mode is not used, the appropriate
high-pass corner frequency is about 0.8 the box
tuning frequency. Alternately, the EX-24,
XEQ-2 and XEQ-3 analog crossover/equaliz-
ers can provide subpassband protection. Roll-
off is 12 dB per octave and the 3-dB-down
points are 30 Hz (EX-24 and XEQ-2) and 16 Hz
or 32 Hz (XEQ-3).
Other high-pass filters are available and one-
third octave equalizers can also be effective at
providing the required protection.
USE IN MULTIPLES
Cone loudspeakers may be stacked for greater
acoustic output and a narrower
beamwidth.
(It
is assumed that all cones are operating in
unison or "in phase.")
At relatively low frequencies
,
below about
150 Hz for the PIM-151, stacking produces
additional acoustic output without altering dis-
persion. When a common signal is applied, a 6-
dB increase in maximum acoustic output oc-
curs.
The cones
"mutually
couple" and act as
one cone with twice the area (therefore twice
the efficiency) and twice the power
capacity.
The additional cone area provides 3 dB more
output and the additional power capacity ac-
counts for the remaining 3 dB.
Specifically, mutual coupling occurs at the fre-
quencies whose wavelengths are longer than
one-quarter the center-to-center distance be-
tween the cones. The highest frequency at
which mutual coupling occurs is calculated
from the following equation:
3,000
D"AX
where DMAJ( is the distance in
inches
and f is the
frequency
In
Hz.
When DMAJ( is greater than one-
quarter wavelength, as would occur if two
PIM-151's were widely spaced, the level in-
crease tends to be limited to the 3-dB power-
handling increase.
ARCHITECTS' AND ENGINEERS'
SPECIFICATIONS
The loudspeaker shall be an optimally vented
low-frequency system. Low frequencies shall
be reproduced by an 8-ohm, 381-mm (15-in.)
woofer with an edge-wound flat-wire 102-mm
(4-in.) voice coil capable of handling 600 watts
long term per EIA RS-426-A and with a sensi-
tivity of 96 dB 1 watt/1 meter. The system shall
reproduce frequencies from 45 to 1,800 Hz.
The recommended crossover frequency shall
be 80 to 200 Hz. Maximum average sound
pressure levels at 1 meter shall be 124 dB with
short-term peaks 6 dB
higher.
The enclosure shall be constructed of 7-ply
void-free birch and finished in black-textured
paint. The enclosure shall have a trapezoidal
footprint. Dimensions shall be 911 mm
(35.9 in.) high, 575 mm (22.7 in.) wide at the
front, 359 mm (14.1 in.) wide althe rear and 439
mm (17.3 in.)
deep.
Enclosure sides shall have
a 15° draft angle. The enclosure shall have a
suspension system approved by an indepen-
dent structural engineer and consisting of three
independent suspension points on the top and
three independent suspension on the bottom,
all of which shall mate with Ancra 42546-10
fittings.
Net weight shall be 34.0 kg (75 lb).
The loudspeaker system shall be the Electro-
Voice PIM-151.
Note: The PIM-151 described above Is the
standard configuration. Acoustic and me-
chanical details will vary when different op-
tions are supplied.
UNIFORM LIMITED WARRANTY
Electro-Voice products are guaranteed against
malfunction due to defects in materials or
workmanship for a specified period, as noted
in the
individual
product-line statement(s) be-
low, or in the individual product data sheet or
owner's manual, beginning with the date of
original
purchase.
If such malfunction occurs
during the specified period, the product will be
repaired or replaced (at our option) without
charge. The product will be returned to the
customer prepaid. Exclusions and LImita-
tions: The Limited Warranty does not apply to:
(a) exterior finish or appearance; (b) certain
specific items described in the individual prod-
uct-line statement(s) below, or in the indi-
vidual product data sheet or owner's manual;
(c) malfunction resulting from use or operation
of the product other than as specified in the
product data sheet or owner's manual;
(d) malfunction resulting from misuse or abuse
of the product; or (e) malfunction occurring at
any time after repairs have been made to the
product by anyone other than Electro-Voice or
any of its authorized service representatives.
Obtaining Warranty Service: To obtain war-
ranty service, a customer must deliver the
product, prepaid, to Electro-Voice or any of its
authorized service representatives together
with proof of purchase of the product in the
form of a bill of sale or receipted invoice. A list
of authorized service representatives Is avail-
able from Electro-Voice at 600 Cecil Street,
Buchanan, Ml 49107 (616/695-6831 or 800/
234-6831). Incidental and Consequential
Damages Excluded: Product repair or re-
placement and return to the customer are the
only remedies provided to the customer.
Electro-Voice shall not be liable for any inci-
dental or consequential damages including,
without limitation, injury to persons or property
or loss of use. Some states do not allow the
exclusion or limitation of incidental or conse-
quential damages so the above limitation or
exclusion may not apply to you. Other Rights:
This warranty gives you specific legal rights,
and you may also have other rights which vary
from state to state.
Electro-Voice Speakers and Speaker Sys-
tems are guaranteed against malfunction due
to defects
in
materials or workmanship for a
period of five (5) years from the date of original
purchase. The Limited Warranty does not ap-
ply to burned voice coils or malfunctions such
as cone and/or coil damage resulting from
improperly designed enclosures. Electro-Voice
active electronics associated with the speaker
systems are guaranteed for three (3) years
from the date of original purchase. Additional
details are included in the Uniform Limited
Warranty statement.
Electro-Voice Flying Hardware (including
enclosure-mounted hardware and rigging ac-
cessories) is guaranteed against malfunction
due to defects in materials or workmanship for
a period of one (1) year from the date of
original
purchase.
Additional details are in-
cluded in the Uniform Limited Warranty state-
ment.
Electro-Voice Accessories are guaranteed
against malfunction due to defects in materials
or workmanship for a period of one (1) year
from the date of original purchase. Additional
details are included in the Uniform Limited
Warranty statement.
Service and repair address for this product:
Electro-Voice, Inc
.,
600 Cecil Street,
Buchanan, Michigan 49107 (616/695-6831 or
800/234-6831 ).
Specifications subject to change without no-
tice.
IE·'I~~=:',:~=~E:'=~~~
.
F®
(C)
Electro-Voice, Inc. 1995 •
Litho in U.S.A.
Part Number 532705 - 9530
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