background image

Description

The Electro-Voice S

b

121 bass module is a

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

b

121. Its deep-

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

TM

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

3

/

8

-inch stands such as the

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

The optional Xp200A electronic system con-

troller complements the characteristics of the

S

b

121. Its mono-summed subwoofer outputs

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

b

121. The amount of en-

hancement can be adjusted to suit the user’s

personal preference.

Crossover

The S

b

121 should be used in conjunction

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

b

121.

(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

b

121, like all other vented systems,

experiences rapidly increasing cone excur-

sion below the box-tuning frequency (60 Hz

for the S

b

121). Acoustic output is also de-

creasing rapidly. Therefore, it is sensible to

protect the S

b

121 and maximize its undis-

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

b

121) is ap-

Sb

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

connectors 

(

1

/

4

-in. phone jacks 

also

provided)

• Four molded-in attachment points

(metric M8 x 1.25) for secure

suspension

Reviews: