Electro-Voice Sb121 Product Manual

Description
The Electro-Voice S 121 bass module is a
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compact, low-frequency enhancement sys-
tem designed for sound reinforcement.
Through the extensive use of computer-aided
design and modeling, Electro-Voice engi-
neers have developed a state-of-the-art por-
table system that combines the advantages
of a long-throw 12-inch woofer in a high-
impact polypropylene structural-foam cabi-
net that is light in weight (only 32.2 lb over-
all).
Low-Frequency Driver Description
The DL12Sx low-frequency driver was spe-
cially developed for the S
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frame geometry provides high-peak excur-
sion ability. At the heart of this driver, is a
magnetic structure optimized to yield the best
possible Thiele-Small parameters to match
the tuned enclosure.
The woofer features beryllium copper lead
wires, a low-mass edge-wound voice coil and
high-temperature materials. The part of the
magnet structure adjacent to the coil is insu-
lated using the exclusive EV PROTEF
process (U.S. Patent #4,547,632). The coil
is driven by a massive, 16-lb magnet struc-
ture.
Enclosure Description
The enclosure is constructed of high-impact
polypropylene structural foam. It provides a
stiff and extremely durable enclosure.
Molded into the cabinet are an integral
carrying handle and a stand socket for
mounting on 1
100BK. Rubber feet that are attached to the
bottom of the cabinet and the mating sock-
ets that are molded into the top provide a
means of stacking systems. Four hanging
inserts are also provided (four metric M8 x
1.25).
Xp200A Electronic System Controller
121. Its deep- The optional Xp200A electronic system con-
troller complements the characteristics of the
S 121. Its mono-summed subwoofer outputs
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provide crossover and infrasonic protection
(see Crossover and Subpassband Protection
sections). Its 24-db-per-octave filters roll-off
response below 37 Hz and above 100 Hz.
The Xp200A also includes a special low-fre-
quency profile circuit that enhances the per-
formance of the S
hancement can be adjusted to suit the user's
TM
personal preference.
3
/ -inch stands such as the
8
121. The amount of en-
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S b 121
300-Watts Nonpowered
Bass Module
• Lightweight (32 lb) and compact
• Very durable structural-foam
enclosure with integral handle
• Stand mountable and arrayable
• 300-watts continuous power
handling (1,200-watts short term)
for high output
• DL12Sx 12-inch woofer with Kevlar
Reinforced cone
®
• Neutrik Speakon high-current
1
connectors ( / -in. phone jacks also
4
provided)
• Four molded-in attachment points
(metric M8 x 1.25) for secure
suspension
Crossover
The S 121 should be used in conjunction
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with an active crossover to roll-off response
above 100-200 Hz, so that bass enhancement
does not "muddy up" vocals or call atten-
tion to the physical location of the S
(The closer the roll-off point is to 100 Hz,
the least the overall sound quality will be
affected by the enhancement of the bass
module.) The roll-off rate should be a mini-
mum of 12-dB per octave.
The optional Xp200A electronic controller
provides a 24-dB-per-octave roll-off above
134 Hz.
Subpassband Speaker Protection
The S 121, like all other vented systems,
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experiences rapidly increasing cone excur-
sion below the box-tuning frequency (60 Hz
for the S 121). Acoustic output is also de-
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creasing rapidly. Therefore, it is sensible to
protect the S 121 and maximize its undis-
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torted output by inserting an active high-pass
filter at a corner frequency somewhat below
box tuning. The roll-off rate should be at least
12-dB per octave. At this minimum rate, a
corner frequency of about 0.8 the box tun-
ing frequency (48 Hz for the S
®
121.
b
121) is ap-
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