S
b
121 300-Watt Nonpowered Bass Module
S
b
121 300-Watt Nonpowered Bass Module
Request P.A. Bible Addition No. Two
(“Power-Handling Capacity”) for more
background on these recommendations.
S
b
121 Connections
The S
b
121 is equipped with one Neutrik
Speakon
®
NL4MP and one
1
/
4
-in. phone jack
connected in parallel, a configuration which
allows for daisy-chaining of speaker systems.
Additional Neutrik Speakon
®
NL4MP and
1
/
4
-in. phone jacks are supplied for maximum
flexibility. Instructions on how to inter-
change the connectors are included with ev-
ery S
b
121.
In continued high-power applications,
Electro-Voice recommends the use of the
Speakon connector. However, to provide a
high level of compatibility, the
1
/
4
-in. phone
jacks are also provided. The Speakon
NL4MP will mate to a NL4FC Speakon con-
nector, which is a 4-pin connector. Figure 3
shows typical wiring configurations using
banana plugs or
1
/
4
-in. phone jacks (the ba-
nana plug provides the more reliable con-
nection). Cable connections should be made
to the 1+ and 1– terminals only. Cables uti-
lizing the Speakon NL4FC are available from
your local dealer.
Multiple Use
The S
b
121 may be used in multiples to in-
crease acoustic output. A 6-dB increase in
maximum acoustic output occurs when two
speaker systems are placed side by side and
paralleled (yielding a 4-ohm load). For op-
eration at very low frequencies, the woofer
cones “mutually couple,” acting as one sys-
tem with twice the effective cone area and
power-handling capacity. Efficiency is
doubled by the increased cone area to pro-
vide 3 dB more output, while the doubled
power capacity provides the potential for an
additional 3-dB gain in maximum acoustic
output.
Mutual coupling occurs when the center-to-
center distance between woofers is less than
one-half the wavelength. For the S
b
121
crossed over at 100 Hz (the frequency pro-
vided by the optional Xp200A electronic
system controller), the maximum distance
for mutual coupling across the band is about
1.5 m (5 ft). When the woofers are spaced
greater than one-half the wavelength, the
level increase is limited to the 3-dB input-
power increase.
The S
b
121 is connected using the connector
marked “input.” A parallel woofer can be
connected using the other jack. This halves
the impedance the amplifier “sees,” from
8 to 4 ohms. Care must be taken not to abuse
the amplifier by connecting impedances
which are too low (refer to amplifier speci-
fications).
Loudspeaker Response Due to the
Acoustical Environment
Several factors must be considered when de-
termining the overall response of a speaker
system in any listening environment. Physi-
cal characteristics of the room itself and
placement of the speakers and listener can
have considerable affect on SPL capability,
perceived and/or measured frequency re-
sponse and stereo imaging.
The low-frequency response of the S
b
121 can
be adversely affected by poor placement. The
S
b
121 was designed for quarter- or half-space
use. This requires that the speaker system be
positioned as close as possible to floor or wall
surfaces (half space) or a floor/wall junction
(quarter space). Corner placement, in most
cases, will reinforce low frequencies the
most. Also, placement in loose cavities or
resonant mountings can seriously degrade the
overall response.
Architects’ and Engineers’
Specifications
The loudspeaker system shall consist of a
12-inch long-throw low-frequency trans-
ducer mounted in a two-piece vented enclo-
sure made of black textured injection-
molded polypropylene structural foam.
The system shall exhibit a 50- to 500-Hz fre-
quency response with a sensitivity of no less
than 94 dB (1 watt /1 meter, 50- to 200-Hz
band-limited pink noise). It will be capable
of handling 300 watts of power by the test
described in the ANSI/EIA RS-426-A 1980.
Paralleled input and output connectors shall
be present, consisting of a combination of
Neutrik Speakon
®
NL4MP and
1
/
4
-in. phone
jacks. Four metric M8 x 1.25 attachment
points capable of supporting the system in a
permanent installation application shall also
be present.
The loudspeaker shall be have a black, per-
forated metal grille covering the woofer.
Overall dimensions shall be 586 mm (23.1
in.) high, 429 mm (16.9 in.) wide, 312 mm
(12.3 in.) deep. The weight shall be 14.6 kg
(32.2 lb).
The loudspeaker system shall be the
Electro-Voice S
b
121.
Uniform 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.
Exclusions 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 EVI Audio
Service or any of its authorized service repre-
sentatives. Obtaining Warranty Service:
To obtain warranty service, a customer must
deliver the product, prepaid, to EVI Audio
Service or any of its authorized service rep-
resentatives together with proof of purchase
of the product in the form of a bill of sale or
receipted invoice. A list of authorized ser-
vice representatives is available from
EVI Audio Service at 600 Cecil Street,
Buchanan, MI 49107 (800/234-6831 or FAX
616/695-4743). Incidental and Consequen-
tial Damages Excluded: Product repair or
replacement and return to the customer are
the only remedies provided to the customer.
