Description
The compact, trapezoidal-shaped Electro-Voice
T251i is a 400-watt, two-way, biampable, con-
stant-directivity speaker system. The system
combines professional-quality components,
arranged in a time-coherent vertical array,
with an unusually robust, installation-
friendly, vented enclosure. The result is clear
and articulate, high-quality sound for per-
manent installation.
The enclosure is constructed of 13-ply void-
free, birch plywood. This high-strength shell
is painted with a textured, neutral, white
paint. Suspension hardware is preinstalled
and three eyebolts are included in the ship-
ping carton. Small rubber feet and mount-
ing screws are also included but not attached
to each system for the less likely situation
where the system will not be suspended.
The high-frequency section of the T251i uti-
lizes a 60° x 40° constant-directivity horn
driven by a wide-bandwidth, two-inch tita-
nium-diaphragm DH2T driver. This driver
uses a unique convex-drive phasing plug
structure for smooth and extended high-fre-
quency performance. The voice coil is
coupled to the diaphragm with EV’s exclu-
sive Resonant Drive
TM
technology. This in-
creases and smooths the high-frequency re-
sponse and reduces the amount of internal
equalization required for flat frequency re-
sponse.
EV’s self-resetting PRO
TM
circuit is built into
the crossover network to guard the compres-
sion driver from damage. If input power to
the driver exceeds the nominal rating, the
PRO™ circuit is activated, reducing the
power delivered to the driver by 6 dB. The
system will remain in this mode of opera-
tion until input power is reduced to a safe
level.
Ring-Mode Decoupling (RMD
TM
)
The T251i controls both acoustical and
mechanical ring modes to provide dra-
matically increased intelligibility, using
techniques learned from the development
of the Electro-Voice X-Array™ concert
speakers. There is much less coloration
of the sound from resonating sources,
leaving only the intended sound to be
heard by the audience. The optimally
vented bass section of the T251i is designed
using Thiele-Small parameters for efficient
performance to below 50 Hz. The DL15ST
high-excursion 15-inch woofer features be-
ryllium copper lead wires with a low-mass,
extended-length, edge-wound voice coil and
high-temperature materials. EV’s unique
Thermo Inductive Ring (TIR
TM
) is placed on
top of the pole piece, where the extended-
length voice coil would normally be exposed,
placing metal in close proximity to the coil
and providing a major heat-transfer path that
helps keep the voice coil cool.
Notes on Installation
Any suspension system is only as strong as
its weakest link. The installer must ensure
the top mounting points have sufficient load
bearing capability to safely suspend the cabi-
net. The initial support cables or chains
should be as close to vertical as possible and
never more than 30° from vertical. Once the
system is installed none of the chains or
cables should touch or rub against the cabi-
net. Local codes and regulations, if they
exceed Electro-Voice’s recommendations,
should be followed at all times.
Electro-Voice recommends that a safety fac-
tor of at least 8:1 be adopted. The
Electro-Voice HS-style suspension compo-
nents supplied in the T251i exceed this rec-
ommended safety factor when the system is
installed in compliance with Electro-Voice
recommendations.
T251i
Trapezoidal Speaker
System
• HS-style suspension hardware is
preinstalled, eyebolts are included
and may be suspended vertically or
horizontally
• Enclosure is paintable (supplied with
white textured paint)
• Ring-Mode Decoupling (RMD
TM
) for
increased intelligibility
• PRO
TM
circuit provides HF driver
protection
• Rotatable constant-directivity
60° x 40° horn
• High-excursion, 400 W, DL15ST 15-in.
woofer
• Biampable, passive network in-
cluded
