S
-40 Compact Monitor
S-40 Compact Monitor
2
low frequencies than typical actual program,
adding an extra measure of reliability. Third,
the test signal includes not only the overall
“long-term average” or “continuous” level -
which our ears interpret as loudness - but also
short- duration peaks which are many times
higher than the average, just like the actual
program. The long-term average level
stresses the speaker thermally (heat). The
instantaneous peaks test mechanical reliabil-
ity (cone and diaphragm excursion). Note
that the sine wave test signals sometimes
used have a much less demanding peak value
relative to their average level. In actual use,
long-term average levels exist from several
seconds on up, but we apply the long-term
average for several hours, adding another
extra measure of reliability.
Specifically, the S-40 is designed to with-
stand the power test described in the revised
EIA Standard RS-426A. The EIA test spec-
trum is applied for eight hours. To obtain
the spectrum, the output of a white noise
generator (white noise is a particular type of
random noise with equal energy per band-
width in Hz) is fed to a shaping filter with 6-
dB-per octave slopes below 40 Hz and above
318 Hz. When measured with the usual con-
stant-percentage bandwidth analyzer (one-
third octave), this shaping filter produces a
spectrum whose 3-dB-down points are at 100
Hz and 1200 Hz with a 3-dB-per octave slope
above 1200 Hz. This shaped signal is sent
to the power amplifier with the continuous
power set at 120 watts into the 3.2 ohms EIA
equivalent impedance, (19.6 volts true
RMS). Amplifier clipping sets instantane-
ous peaks at 6 dB above the continuous
power, or 480 watts peak (39.2 volts peak).
This procedure provides a rigorous test of
both thermal and mechanical failure modes.
Protection Circuitry
Both the woofer and the tweeter employ in-
dependent protection circuits to prevent
against accidental overdrive and improve
system reliability. In the woofer circuit, a
solid state self-resetting switch is activated
once the safe level to the woofer is exceeded
(approximately 60 watts). This switch then
inserts a high positive current coefficient
resistor (HPCCR) in series with the woofer.
The resistance of the HPCCR increases as
the drive level to the woofer increases and
limits the power being delivered to the
woofer. The HPCCR is similar to a lamp
and will produce light that is visible thru the
port when activated. This is an indication to
reduce the gain of the power amp if output
compression is to be avoided. The maximum
acoustic output is achieved just before the
protection circuit is activated.
The tweeter protection circuit behaves in a
similar manner, except a fixed resistor is used
in place of the HPCCR which attenuates the
power to the tweeter by approximately 6 dB.
Installation Notes
On the back of the S-40 are (2) 1/4"-20
threaded inserts. These are intended to be
used with mounting systems which have 2-
3/8" mounting centers, such as the
Omnimount Systems Series 25.
A U-type bracket, the S-40MB is also avail-
able. This will allow the S-40 to be mounted
on walls or ceilings. A microphone stand
adaptor is also included. Complete mount-
ing instructions are included with the S-
40MB.
Care should be taken to ensure that the cho-
sen fixing point is strong enough to support
the S-40. Care should also be taken to en-
sure that the S-40 is not exposed to direct
precipitation.
If the speaker system is not used with one of
the mounting brackets, such as on a book-
shelf, then the rubber feet that are included
with the S-40 should be attached to the
speaker. If the speaker is placed on the bot-
tom side, then a rubber foot should be at-
tached to each of the two rear corners only.
This will compensate for the 3° draft that is
molded into the cabinet, and allows the baffle
to sit perpendicular to the surface that the
speaker is placed on. If the speaker is to be
placed on its side, then a rubber foot should
be attached to each of the four corners. The
nameplate that is attached to the grille may
be rotated depending on which mounting ori-
entation is used.
Architects' and Engineers'
Specifications
The loudspeaker shall be a two-way system
consisting of a 13 cm (5-1/4") low-frequency
loudspeaker, 2.5 cm (1 inch) high-frequency
loudspeaker and frequency dividing network
installed in a vented enclosure. The divid-
ing network crossover frequency shall be
3,500 Hz. The dividing network shall in-
clude protection circuits for both the low-
frequency loudspeaker and the high-fre-
quency loudspeaker. The loudspeaker sys-
tem shall meet the following performance
criteria: Power handling, 120 watts per EIA
RS-426A. Frequency response, … 3 dB from
85 Hz to 20 kHz. Pressure sensitivity, 85
dB SPL at one watt, 100 Hz to 10 kHz meas-
ured at a distance of one meter on axis. Im-
pedance, 4 ohms nominal, 3.7 ohms mini-
mum. The enclosure shall be molded of high
impact polystyrene structural foam. The unit
shall be 24.9 cm (9.8 inch) high, 17.8 cm
(7.0 inch) wide, 15.0 cm (5.9 inch) deep. The
loudspeaker system shall be the Electro-
Voice model S-40.
Limited Warranty
Electro-Voice products are guaranteed
against malfunction due to defects in mate-
rials or workmanship for a specified period,
as noted in the individual product-line
statement(s) below, or in the individual prod-
uct data sheet or owner’s manual, beginning
with the date of original purchase. If such
malfunction occurs during the specified pe-
riod, the product will be repaired or replaced
(at our option) without charge. The product
will be returned to the customer prepaid. Ex-
clusions and Limitations: The Limited
Warranty does not apply to: (a) exterior fin-
ish or appearance; (b) certain specific items
described in the individual product-line
statement(s) below, or in the individual prod-
uct data sheet or owner’s manual; (c) mal-
function 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 Service or any of its authorized ser-
vice representatives. Obtaining Warranty
Service: To obtain warranty service, a cus-
tomer must deliver the product, prepaid, to
Electro-Voice Service or any of its autho-
rized service representatives together with
