S15MFloorMonitor
S15MFloorMonitor
tive metal grille complete the picture and
ensure that the S15M speaker system is ide-
ally suited to a long and reliable life on the
road.
Frequency Response
The combination of a 15-inch woofer, 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 3.05 meters
(10 feet), using a 4-volt swept sine-wave in-
put in an anechoic chamber. No external
equalization was used. Figure 1 has been
averaged and corrected for 1 watt at 1 meter.
Connections
The S15M is equipped with two parallel
1/4-inch phone jacks. (The S15M-E has two
parallel Neutrik Speakon®NL4MP connec-
tors.) Another system can be connected in
parallel by using the other connector. Care
must be taken not to abuse the amplifier by
connecting impedances which are too low.
Constant-Directivity Speaker System
The crossover frequency and speaker com-
ponentgeometries have been selected so that
the directional characteristics of the woofer
and constant-directivity horn match at the
crossover frequency to create a special sys-
tem type — the constant-directivity system.
At higher frequencies the vertical coverage
pattern remains constant and the horizontal
pattern smoothly transitions to a 55° angle
above 5,000 Hz. Response within the 80° x 55°
rated coverage angle is uniform, which
means dependable coverage without “hot
spots” or dead zones at certain frequencies.
The 80° x 55° dispersion characteristic also
helps avoid early reflections from nearby
surfaces which could degrade performance.
The controlled directivity of the high- and
low-frequency transducers also eliminates
response irregularities caused by diffraction
off nearby enclosure edges and, in combi-
nation with an essentially flat on-axis fre-
quency response, produces a total acoustic
power output that is uniform with frequency.
Directivity
A unique feature of the S15M is the con-
stant-directivity dispersion provided by the
80° x 55° horn. The polar response of the
system at selected one-third-octave band-
widths is shown in Figure 5. These polar
responses were measured in an anechoic
environment at 6.1 meters (20 feet) using
one-third-octave pink-noise inputs. The fre-
quencies selected are fully representative of
thepolarresponseofthesystem. Beamwidth
of the system utilizing the complete one-
third-octave polar data is shown in Figure 6.
Directivity factor, R, and directivity index,
Di, are plotted in Figure 7.
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
typical music and tests the thermal and
mechanical 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 S15M passes ANSI/EIA
RS-426-A 1980 with the following values:
RSR = 5.98 ohms (1.15 x RE)
PE(MAX) = 250 watts
Test voltage = 38.67 volts rms,
77.33 volts peak (+6dB)
The “peak” power-handling capacity of a
woofer is determined by the peak test volt-
age amount. For the S15M, a 77.33-volt-
peak-test voltage translates into 1,000-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. Providedtheamplifier can reproduce
the signal accurately, without clipping, the
woofer will also perform accurately and re-
liably, even at these levels.
Amplifier Power Recommendations
As noted in the Power-Handling Capacity
section, above, the S15M has a random-
noise power capacity of 250 watts long-
term (1,000-watts peak) per ANSI/EIA RS-
426-A 1980. The following guidelines will
help relate this to an appropriate power am-
plifier output rating.
1. To use the S15Mtofullcapacity,skilled
expertsinsound-systeminstallationand
operation will obtain the best results if
the power amplifier is 2.0 to 4.0 times
the long-term average noise power rat-
ingofthespeakersystem. FortheS15M
this is 500 to 1,000 watts.
The caution cannot be made strongly
enough, however, that this arrangement
is only for experts or those who can disci-
pline themselves against “pushing” the
system for ever-higher sound levels and
who can avoid “accidents” such as cata-
strophic feedback or dropped micro-
phones.
2. Amoreconservative,“normal”amplifier
size, which will produce audible results
nearly equal to those of the “expert” rec-
ommendation, is 1.0 to 1.4 times the
long-term average noise power rating
of the speaker. For the S15M this is
250 to 350 watts.
3. To be very conservative, one can use an
amplifier rated at 0.5 to 0.7 times the
long-term average noise power rating
of the loudspeaker. For the S15M this
is 125 to 175 watts.
Request P.A. Bible Addition No. Two
(“Power-HandlingCapacity”)for more back-
ground on these recommendations.
Service
In the unlikely event the S15M requires
service, the woofer and driver can both be
replacedorserviced from the front. A service
data sheet is available from Electro-Voice.
Architects’ and Engineers’
Specifications
The loudspeaker shall be a compact vented-
box type. The low frequencies shall be
reproduced with one 250-watt (ANSI/EIA
