Electro-Voice 18BX Manual

SPECIFICATIONS
Usable Frequency Response in a Typical
Vented 8.0-Cubic-Foot Enclosure
(1 wattJ1 meter; see Figure 1):
30-4,000 Hz
Sound Pressure Level (1 wattJ1 meter):
101 dB
Long-Term Average Power Handling
Capacity (per EIA RS-426-A 1980; see
Power Handling section):
400 watts
Nominal Impedance:
8 ohms
Voice-Coil Diameter:
63.5 mm (2.5 in.)
Thiele-Small Driver Parameters
'. (free-air resonance frequency):
31 Hz
a
ES
(electromagnetic
a
at f.):
0.33
OMS
(mechanical
a
at f.):
6.98
(a •• am.)
a
rs (total
a
at f.:
(a ..
+
am.) :
0.31
V (volume of air having same acoustic
AS
d . . )
compliance as river suspension :
623.0 liters (22.0 ft3)
7]0
(half-space reference efficiency):
5.2%
Vo (peak displacement volume of
diaphragm: So x Xmax):
0.463 liters (0.0164 fP)
So (effective diaphragm area):
0.114 m 2 (176.7 in.2)
X (peak linear displacement of
d~phragm):
4.06 mm (0.16 in.)
R. (dc resistance of voice coil):
6.0 ohms ±10%
Mounting Information
(see Installation section),
Mounting Hole Diameter
(eight evenly spaced holes):
7.1 mm (0.28 in.)~etter "L" drill
Bolt Circle Diameter:
370 mm (14.56 in.)
Baffle Opening Diameter,
Front Mounting:
422 mm (16.63 in.)
Rear Mounting:
416 mm (16.38 in.)
Optional Mounting Accessory:
SMH-1 mounting hardware kit
Dimensions (see Figure 2),
Overall Diameter:
460 mm (18.10 in.)
Overall Depth:
203 mm (8.0 in.)
Net Weight:
9.9 kg (22 Ib)
Shipping Weight:
12.0 kg (26.5 Ib)
DESCRIPTION
The Electro-Voice 18BX is an 18-inch speaker
designed for professional, high-level, high-qual-
ity musical instrument systems. For bass guitar
use, the 18BX can provide stronger-than-usual
output at the lowest bass tones (30-50 Hz), and
its high-frequency response is tailored for a
traditional bass sound. The 18BX incorporates
voice-coil and suspension refinements, includ-
ing beryllium copper flatwire leads, that have
improved performance. Power capacity is 400
watts per EIA RS-426-A 1980. The Power-
Handling section describes these ratings in
detail.
The construction of the 18BX features an over-
hung low-mass edge-wound voice coil on a
rugged laminated polyimide coil form, driven by
188X
18-lnch Long-Throw
Bass
Guitar Loudspeaker
• Contoured response for bass
guitar
• Improved low-frequency
performance-less distortion
at low frequencies
• Ideal upgrade speaker
• 400 watts long-term power
capacity
• Edge-wound flat aluminum
wire for maximum output and
"bulletproof" reliability
• 1 01-dB sensitivity
our large, 16-lb magnetic structure. Also fea-
tured are a heavy-duty curvilinear cone and a
fatigue-resistant cone suspension. Both the
coil and magnetic structure are vented. All of
this is packaged around a rugged, eight-spoke,
diecast aluminum frame.
The 18BX may be front- or rear-mounted with-
out an adapter. The optional SMH-1 speaker
mounting kit facilitates front mounting (see In-
stallation section).
RECOMMENDED ENCLOSURES
Replacement Use In Existing Enclosures
The 18BX will often be used to replace inferior
speakers in existing enclosures. Mechanical
and electrical characteristics are such that the
superior efficiency, sound quality and reliability
of the 18BX will be realized in virtually any
sealed, vented (bass reflex) or horn-loaded
enclosure.
Vented Enclosures
The most extended, lowest distortion and best-
controlled bass performance is usually realized
in properly designed vented enclosures. In
such designs, the vent, or port, actually repro-
duces the lowest octave or so of bass re-
sponse. The vent is driven to full acoustic
output by a relatively small motion of the speaker
cone itself, acting through the air contained
within the enclosure. The excursion of the 18BX
at these frequencies is much reduced com-
pared to sealed or open-backed enclosures,
directly reducing harmonic distortion.
Often, in bass guitar systems, a perfectly flat
response is not as important as a controlled
response. Typical sound-reinforcement sys-
tems are "tuned," so the enclosure provides the
flattest possible response. Generally, bass-
guitar system performance is improved if the
enclosure is vented or tuned for roughly the