Electro-Voice Sentry IVB Data Sheet

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SPECIFICATIONS
Frequency Response: but in high level sound reinforcement, horn principle for increased efficiency
50 to 18,000 Hz high level playback systems, etc. and lower distortion. The design of the
(see Figure 1) enclosure permits linear low-frequency
EIA Sensitivity (on axis measurements): The midrange and tweeter horn designs response to within a few cycles of the
52 dB represent the first significantly new theoretical enclosure cutoff frequency
,Ç ‘ sectoral design in 25 years. With vertical of 50 Hz. Two 12-inch cone drivers are
Sound Pressure Level (4! on axis, BOW): dispersion of greater than G0-degreesat used in the folded horn low-frequency
117 dB all frequencies and extremely stable section.
Impedance: horizontal dispersion at 120-degrees
8 ohms nominal virtually throughout the frequency The crossover provides push clip termi-
Power Handling Capacity: range, these horns offer a uniformity of nals for connection of all components.
50 W (see explanation) coverage which practically eliminate
Finish: “hotspots” and “dead areas” in the __ À female phone plug receptacle is
Utility Black control room or elsewhere (see Figure provided for bi-amping high-frequency
2). Totally new drivers are associated input. For those who wish to use an
Size: with the midrange and high-frequency active crossover, all high-frequency
70.5 em (27%) w. x 52.3 cm components to offer both ruggedness information should be routed into the
(20-5/8") d. x 129 cm and linear response. crossover via this receptacle. In this way
(50%") h. - in normal configuration the crossover between woofer and
Weight: The woofer section utilizes the folded midrange (400 Hz) is bypassed.
67 Ка (148 pounds)
DESCRIPTION AND APPLICATIONS
The Electro-Voice Sentry VB incorpo-
rates many new and innovative design
ideas which represent a significant
advance in state-of-the-art speaker
design. The 3-way, all horn loaded
system offers absolute minimum distor-
tion through all frequencies while
providing unequalled efficiency and
uniformity over the entire frequency
range. With high power handling capac-
—|5db |—
RESPONSE IN db
. : de в 8 8 883883 в & © 85887 Nw = 4 y
ity, extremely uniform and wide disper- Ea. E 5858: 885 Ей z z = E
sion, and linear frequency response, the FREQUENCY IN HERTZ E
Sentry IVB offers versatility for appli- FIGURE 1 — Frequency Response
cations in not only studio monitoring, (average axis pressure under anechoic conditions)
A high-frequency rolloff attenuator is
provided on the crossover which
increases effective power handling
capacity by smoathly attenuating
tweeter input power.
POWER HANDLING CAPACITY
In an effort to provide a meaningful
power rating, the frequency spectrum of
the lead guitar in several prominent
groups was band-analyzed. A filter was
designed that would shape white noise
(a sound similar to between-station FM
noise, consisting of all frequencies from
20 to 20,000 Hz simultaneously) to the
typical lead guitar spectrum. The lead
guitar frequency spectrum is far more
demanding at the frequency extremes
than voice or conventional music pro-
gram material. Filtered white noise is
fed into the system at various levels to
determine the power handling capacity.
With the attenuator in the No. 1
position (flat) the continuous power
handling capacity (above defined and
assuming a nominal 8 ohm load) is 50
watts. With the attenuator in the No. 2
position, the power handling is 75 watts
continuous. In No. 3 position, it is 125
watts continuous. The fourth attenuator
position almost completely attenuates
the upper range of the tweeter output
and significantly increases power han-
dling capacity.
Figure 6 shows continuous sine wave
power handling with relation to fre-
quency. The graph is designed to be
used to calculate power handling when
unusual program sources with sub-
stantial high frequency energy are
anticipated. A continuous voltage of 4
volts into the tweeter should not be
exceeded when using noise inputs.
CAUTION: While the normal area of
maximum peak power in program
material tends to be in the 500 Hz
range, fast winding of professional tape
machines at five to six times the normal
speed shifts the peak power area into
the tweeter which, in effect, causes the
tweeter to function as a full-range
speaker, In addition to shifting the
power spectrum, transient times are
accelerated and destructive forces are
substantially increased. The tweeter will
not tolerate much of this type of treat-
- ment, so care should be taken when
high winding to assure that the tape is
lifted from the playback head.
CONNECTING THE SENTRY IVB
The Sentry |VB is shipped in two sepa-
rate packages. After unpacking the low-
frequency section, the high-frequency
subassembly may be unpacked and
assembled. Seven brackets and the
appropriate hardware for mounting are
shipped with the high-frequency
assembly. (See Figure 3 for normal
assembly.)
In the normal mounting configuration,
the midrange/crossover assembly is
secured to the top of the low-frequency
section, and the tweeter is suspended in
the upper wave path of the low-
frequency section. If the high-frequency
assembly is used with a different low-
frequency system, the tweeter can be
suspended from the front of the mid-
range horn by using the 12.7 in. long
brackets and four 410 lag screws.
HORIZONTAL
DISPERSION
EHADED AÑEA REPRESENTS DIFFERENCE BETWEEN OCTAVE
BAND POLAR CURVES BETWEEN 600 and 18,000 Hz
SCALE IS & 48 PER DIVERION
Phasing — In the classical configuration
for the 12 dB per octave crossover, the
woofer should be connected out of
phase with the high-frequency compo-
nents. However, since phasing con-
ditions in an unspecified electrical cross-
over cannot be anticipated, the fol-
lowing procedure is recommended for
optimum phasing in any given situation:
introduce a sine wave at the crossover
frequency (between 400 and 450 Hz
depending on the crossover) to the
system. By switching phasing of the
high-frequency half of the system, select
the phasing configuration which gives
the loudest output at any given
crossover frequency.
VERTICAL
DISPERSION
SCALE 16 6 di PEA DIVISION
FIGURE 2 — Frequency Dispersion
ELECTRICAL CONNECTIONS
The crossover section is shipped with
the midrange driver already wired and
the leads for the tweeter and the low-
frequency section already attached. The
white striped lead corresponds to the
positive terminal (T1) on both tweeter
and midrange driver, and the woofer
connection is provided for with a phone
plug. (Phone plug tip corresponds to
positive or T1 terminal, while the sleeve
is the negative terminal.) When
designing or employing a low-level cross-
over in bi-amping, the following criteria
should be used:
Crossover frequency—400 to 450 Hz,
Crossover sloping—
12 dB per octave or greater.
In the event that this wiring is discon-
nected for one reason or another, it
must be noted that the tweeter and
midrange sections should be connected
in phase with one another while the
low-frequency section should be out of
phase with the tweeter and midrange.
Output leads (power leads) from the
amplifier should be connected at the
input terminals with the positive lead
connected to the red input terminal,
causing the low-frequency section to be
in phase with the amplifier output. (see
Figure 5.)
TWEETER PROTECTION
A tweeter protection device is provided
to allow maximum performance with-
out tweeter damage, The device senses
for maximum safe voltage to the
tweeter and opens the tweeter circuit (1
millisecond relay) if that voltage is
exceeded. When safe voltage is resumed
the tweeter is instantly brought back
into the circuit.
The protector is located under the horn
in front of the crossover. The wires
from the input of the protector should
be connected to the tweeter terminals
on the crossover (striped lead to black
terminal) and the output wires of the
protector to the tweeter itself (striped
lead to terminal T1).
INSTALL OPPOSITE
SIDE IN SAME WAY
1/4-28 x 3/8 SCREW
7,5" LONG BRACKET
FLAT WASHER {1
10-32 x 1-1/4
SCREW
ти — o — O == | |
KNURLE + _—_
THUMB o
SCREWS |
8-32 NUT ое
6” LONG BR E
AE 8-32 x 9/16 SCREW
FIGURE 3 — Bracket Assembly
STRIPED WIRE
T1
OF TWEETER
FIGURE 4 — Wiring of Tweeter Protector
STRIPED WIRE TO
+ INPUT OF STR
STRIPED WIRE TO T1
OF MID-RANGE DRIVER
STRIPED WIRE TO
PHONE JACK TIP
FIGURE 5 — Crossover Wiring
‚ NOTE: When the system is operating at
maximum power threshold, the tweeter
may switch in and out with a clicking
sound. To relieve the tweeter, either
lower the power or roll the tweeter off
one additional position at the crossover,
a FEET ETRY
y 8 & 883883
SYSTEM LAYOUT
Accurate system layout with the Sentry
IVB may be made by referring to the
axial frequency response of Figure 1 as
well as the octave band random noise
polar response of Figure 2. From these
figures, the sound pressure level avail-
able at a distance of 4 feet with full
power in (50 watts) may be determined
for any octave band at any angle.
Level Variations with Distance: Non-
Reverberant Environments: In a non-
-reverberant environment (such as out-
of-doors), sound pressure level will drop
6 dB every time the distance from the
speaker is doubled (inverse square law).
The nomograph of Figure 7 shows the
dB losses to be expected as distance
from the Sentry |VB is changed.
Level Variations with Distance:
Reverberant Environments Indoors:
Where sound is reflected from walls and
other surfaces and the environment is
reverberant, there is a point (the
“critical distance") beyond which the
“reverberant field” dominates and
sound pressure is nearly constant. This
distance is typically ten to twenty-five
feet from the speaker and is shortest for
the most reverberant rooms. Because of
the reverberant field, the sound pressure
level obtainable in a room is much
higher and more constant than that
predicted by inverse square law alone.
However, the information in Figures 1
and 2 is still necessary in order to obtain
satisfactory distribution of the sound
direct from the loudspeaker (‘direct
field"), which still follows the inverse
square law,
In installations where applicable, it is
good practice to make sure that the
direct field is no more than 12 dB below
В 8 8 88888:
FREQUENCY IN HERTZ
FIGURE 6 — Power Handling Chart (average sine
wave power, nominal 8 ohm load)
ATTENUATOR CROSSOVER POSITION
4
THYHZ
THA E
IHN S
EH OL
IHM GL
FHA OT
the reverberant field if satisfactory
intelligibility is to be obtained. This
condition is fulfilled if the listener is no
more than four times critical distance
from the loudspeaker.
Level Variation with Power: Each time
the power delivered to the speaker is
halved, a drop of 3 dB occurs, in any
type of environment. The nomograph of
Figure 7 shows this effect,
ADD TO THE
LARGER
READING
3.00 dB
2.50
2.10
1.70
1.40
1.10
97
79
63
51
43
35
26
WHEN TWO
SIGNALS
DIFFER BY:
0 dB
=й «= ==
кю а © © 09 Ч с) (л № 0 О —
Level Variations due to Multiple
Speakers: The chart above indicates the
total sound pressure level resulting from
two loudspeakers aimed at the same
point. This chart greatly facilitates lay-
out of systems employing multiple
speakers.
ENVIRONMENT
The Sentry | VB professional system was
designed for one-quarter to one-half-
space use. The unit should be as close to
reflecting planes as possible so that out
of phase low-frequency irregularities
from the reflected wave may be
avoided. Cavities around the device are
Undesirable, as cavity resonances may be
excited.
ARCHITECTS AND ENGINEERS’
SPECIFICATIONS
The speaker is a 3-way all-horn-loaded
wide-range system with high power-
handling capacity. Low end should
consist of a folded horn housing two
12" cone drivers. Midrange should
consist of a 120° sectoral horn and
driver, and the high end should consist
ofa 120° sectoral tweeter with integral
driver. Electrical crossover frequencies
should be at 400 Hz and at 3500 Hz.
Low-frequency cutoff should occur at
approximately 50 Hz. Frequency
response should be smooth and flat (in
%- to Y-space coupling) from 50 Hz to
18,000 Hz, Dispersion of the system
should be uniform with no lobes from
600 Hz to 18,000 Hz. Horizontal disper-
sion should be 120° with vertical
dispersion at 60°.
de Loss Vs
SPL Rating
DISTANCE dB—SPL
120
6'
a"
10"
50"
80"
100"
200"
300’
500'
A tweeter protector is provided to save
the tweeter from surges of excess power
such as feedback and some forms of
program material. it automatically dis-
connects the tweeter as power exceeds
the tweeter's power handling capacity
(see Figure 6) and reconnects the
tweeter when power levels are safe.
In the crossover No. 1 position, power
handling should be 50 watts continuous
(8 ohm nominal load) using a suitable
noise input shaped to the lead guitar
spectrum; No. 2 position, 75 watts; No.
3 position, 125 watts, and No. 4
substantially higher,
POWER (watts) dB—SPL
125
100 120
50
30 115
20
10 110
5
105
2
I 100
5
95
„2
«1 90
FIGURE 7 — Nomographs
WARRANTY (Limited) —
Electro-Voice Sentry Loudspeakers and
accessories are guaranteed for five years
from date of original purchase against
malfunction due to defects in workman-
ship and materials. IT such malfunction
occurs, unit will be repaired or replaced
(at our option) without charge for
materials or labor if delivered prepaid to
the proper Electro-Voice service facility.
Unit will be returned prepaid. Warranty
does not cover finish, appearance items,
burned coils, or other malfunction due
to abuse or operation at other than
specified conditions. Repair by other
than Electro-Voice or its authorized
service agencies will void this guarantee.
For correct shipping address and
instructions on return of Electro-Voice
products for repair and locations of
authorized service agencies, please
write: Service Department,
Electro-Voice, Inc., 600 Cecil Street,
Buchanan, Michigan 49107 (Phone:
616/695-6831) or 8234 Doe Avenue,
Visalia, California 93277 (Phone:
209/625-1330,-1).
Electro-Voice also maintains complete
facilities for non-warranty service.
Specifications subject to change
without notice.
Part Number 53810 — 046
a Gulton coman» ELECTRO -VOICE, Inc., 600 CECIL ST., BUCHANAN, MICH. 49107
MANUFACTURING PLANTS AT B BUCHANAN, MICH. B NEWPORT, TENN. @ SEVIERVILLE, TENN, B GANANOQUE, ONT, B LITHO IN U.S.A,