Enclosure Construction; Frequency Response; Constant-Directivity Speaker System; Power-Handling Capacity - Electro-Voice Sx80 Specifications

Enclosure Construction

The Sx80 enclosure is contructed of very-
durable High-impact polystyrene that is hard
to dent, scratch, or break. This enclosure
allows for molded in attachment points for
the optional Sx80MB mounting bracket
or for use with an OmniMount® Series
75 mounting system.
The enclosure is paintable to match any de-
cor. It is recommended, however, that a small
area should be tested with the desired paint
in order to ensure that there are no adverse
effects and that the paint has sufficient ad-
hesion. Care should be taken not to get paint
onto the woofer cone or into the horn throat.

Frequency Response

The combination of a 203-mm (8-inch)
woofer, a wide-bandwidth high-frequency
driver and an equalized crossover results in
the wide and smooth overall response shown
in Figure 1. This response was measured at
1 meter (3.281 feet), using a 2.83-volt swept
sine-wave input in a full-space anechoic
chamber using the internal passive crossover.
No external equalization was used.
Figure 1 also shows the half-space measure-
ment of the Sx80 loudspeaker. This curve
gives an indication of how the system will
respond when mounted on a wall, which is a
likely application. This response was also
measured at 1 meter (3.281 feet), using a
2.83-volt swept sine-wave input using the
internal passive crossover. No external
equalization was used.
Connections
The Sx80 is equipped with push-pin input
connectors. Care should be taken to ensure
that the correct polarity is observed when
connecting the Sx80. The push-pins are
marked with + for positive and - for nega-
tive.
When Sx80s are connected in parallel, care
should be used to be sure that the impedance
does not become too low for the power am-
plifier being used. The nominal impedance
of the Sx80 is 8 ohms.
2
Sx80 175-Watt T wo-Way Speaker System

Constant-Directivity Speaker System

The crossover frequency and speaker com-
ponent geometries have been selected so that
the directional characteristics of the woofer
and constant-directivity high-frequency horn
match at the crossover frequency to create a
special system type, the constant-directivity
system. At higher frequencies the horizon-
tal coverage pattern remains constant and the
vertical pattern smoothly transitions to a 90°
angle above 5,000 Hz. Response within the
90° x 65° rated coverage angle is uniform,
which means dependable audience coverage
without "hot spots" or dead zones at certain
frequencies. The 90° x 65° dispersion char-
acteristic also helps avoid early reflections
from nearby floor or side-wall surfaces which
could degrade performance. The controlled
directivity of the high- and low-frequency
transducers also eliminates response irregu-
larities caused by diffraction off nearby en-
closure edges and, in combination with an
essentially flat on-axis frequency response,
produces a total acoustic power output that
is uniform with frequency.
Directivity
A unique feature of the Sx80 is the constant-
directivity dispersion provided by the
90° x 65° horn. The polar response of the
system at selected one-third-octave band-
widths is shown in Figure 2. These polar
responses were measured in a full-space
anechoic environment at 6.1 meters (20 feet)
using one-third-octave pink-noise inputs.
The frequencies selected are fully represen-
tative of the polar response of the system.
Beamwidth of the system utilizing the com-
plete one-third-octave polar data is shown
in Figure 3. Directivity factor, R
rectivity index, D

Power-Handling Capacity

Electro-Voice components and systems are
manufactured to exacting standards, ensur-
ing they will hold up, not only through the
most rigorous of power tests, but also
through continued use in arduous, real-life
conditions. The EIA Loudspeaker Power
Rating Full Range (ANSI/EIA RS-426-A
1980) uses a noise spectrum which mimics
and di-
Q,
, are plotted in Figure 4.
i
typical music and tests the thermal and me-
chanical capabilities of the components.
Electro-Voice will support relevant addi-
tional standards as and when they become
available. Extreme, in-house power tests,
which push the performance boundaries of
the woofers, are also performed and passed
to ensure years of trouble-free service.
Specifically, the Sx80 passes ANSI/EIA
RS-426-A 1980 with the following values:
R = 6.21 ohms (1.15 x R
SR
R = woofer DCR = 5.4
E
P = 175 watts
E(MAX)
Test voltage = 32.97 volts rms,
65.93 volts peak (+6dB)
The "peak" power-handling capacity of a
woofer is determined by the peak test volt-
age amount. For the Sx80, a 65.93-volt peak
test voltage translates into 700-watts short-
term peak power-handling capacity. This is
the equivalent of four times the "average"
power-handling capacity, and is a peak that
can be sustained for only a few milliseconds.
However, this sort of short duration peak is
very typical in speech and music. Provided
the amplifier can reproduce the signal accu-
rately, without clipping, the woofer will also
perform accurately and reliably, even at these
levels.
Amplifier Power Recommendations
As noted in the Power-Handling Capacity
section, above, the Sx80 has a random-noise
power capacity of 175 watts long term (700
watts peak) per ANSI/EIA RS-426-A 1980.
The following guidelines will help relate this
to an appropriate power amplifier output
rating.
1. To use the Sx80 to full capacity, skilled
experts in sound system installation and
operation will obtain the best results if the
power amplifier is 2.0 to 4.0 times the
long-term average noise power rating of
the speaker system. For the Sx80 this is
350 to 700 watts.
The caution cannot be made strongly
enough, however, that this arrangement
is only for experts or those who can dis-
cipline themselves against "pushing"
the system for ever-higher sound lev-
els and who can avoid "accidents" such
)
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