Electro-Voice 12TRX & 12TRXB Data Sheet

oT 5 Specifications and
por EE р ТАН Instructions
ELECTRO-VOICE, INC. | Models 12TRX and 12TRXB
BUCHANAN, MICHIGAN a
i Triaxial Speaker Systems
Incorporating all the design advantages of the famous E-V Radax coaxial prin-
ciple, the E-V Models 12TRX and 12TRXB Triaxial Reproducers include also
the latest developments in the art of reproducing the highest audible frequencies
through the use of an integral Super-Sonax VHF driver, The 12TRX employs
the T35 VHF driver, while the sensitivity of the 12TRXB is matched by the
triaxially mounted T35B. Bass response is phenomenal, affording for the first
cme, pleasing musical balance without the masking effects previously experienced
from extended high-frequency reproduction. Tailored to optimum listening
requirements, these new developments insure even, smooth coverage of the entire
listening area. This is achieved by the exclusive concentric mounting design
of all reproducing elements.
FEATURES — Exclusive, E-V engineered features include true concentric mounting
of all reproducing elements insuring smooth room coverage; augmented balanced
bass response in conjunction with smooth extended “silky” high-frequency repro-
duction; carefully tailored midrange characteristic to provide realism and “‘pres-
ence” at usual sound levels, offsetting ear insensitivity at low volume; adjustable
brilliance control to allow matching to room acoustics, compensating for high-
frequency absorptive effects of rugs and draperies; crossover network with full
12 db-per-octave slope minimizes distortion; edgewise wound aluminum voice
coil design affording 18% more efficiency and consequent damping of transient
distortion; heavy magnet structure.
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SPECIFICATIONS я
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12TRXB 12TRX —
Frequency Response: 35 to 15,000 cps 30 to 15,000 cps C
(In recommended Aristocrat Enclosure) <
RETMA Sensitivity Rating: 46 db 49 db С
Free-Space Cone Resonance: 40-50 cps 35-45 cps я
Power Handling Capacity: =
Program Material: 20 watts 25 watts =
| e Peaks: 40 watts 50 watts =
Fig. 1 — Dimensions Model 12TRX i. ;
Critical Damping Factor: =
re In Aristocrat enclosure: 4 2 =
A - | In an infinite baffle: 2.5 1 5
impedance: 16 ohms 16 ohms =
Mechanical Crossover: 2000 cps 2500 cps =
Pa
Electrical Crossover: Integral 3500 cps Separate 3500 cps =
Dispersion: 1 ke - 180°; 5 kc - 130°; 10 ke - 100° =
Magnet Weight: 1lb3oz 3% lb
Size: 12% in. dia. x6 in. 12% in, dia. x7% in.
deep overall deep overall
Mounting: Four %32-in. holes equally spaced on
11%-in. circle
Baffle Opening: 10% in. 10% in.
BLACK :
чи“ Net Weight: 10% Ib 24 Ib
Me CABLE | Shipping Weight: 14 1b 32 Ib
Fig. 2 — Dimensions Model 12TRXB
INSTALLATION
Optimum bass response with the E-V 12TRX and 12TRXB triaxial units is
obtained in the E-V Aristocrat radiator Klipsch-licensed corner horn. Where a
baffle is available of the "infinite" type, such as a closet, or a wall with large
volumetric capacity available behind the cone, excellent results will be obtained
in the accomplishment of the bass range. The ideal volume is 14 cubic feet or —
more, for with this volume the low free-space resonance of the bass cone becomes | :
the controlling factor in achieving the first octaves. This response will be fat —
to 35-45 cps.
Where restricted space of only 4 to 8 cubic feet is available for housing the
speaker, bass response will suffer and the low range will be compressed by about
1 octave. This deficiency may be offset somewhat by reinforcing the bass through
porting the enclosure. Start with an opening of about 130 square inches and
gradually decrease this area until most pleasing response is obtained. More
accurate design data on this form of enclosure is available from the Reproducing
Components Division of Electro-Voice, and in the many articles on enclosure
design now published.
Reflections on the interior cavity will cause ragged response, indicated by undue
reinforcement at certain frequencies and cancellation at others, unless sound
absorbent material is used on at least three of the opposing interior sides. The
material may be “Kimsul” 2 inches thick or equivalent. “Kimsul” is available
from any building supply house as a product of the Kimberly-Clark Manufactur-
ing Company. Glass wool or glass block is good, but must be covered with
cheese cloth to confine the fibers. Blankets, jute, and rug pads are satisfactory
Fig. 3 — Pictorial Wiring Diagram substitutes.
Model 12TRX on Aristocrat Mounting Board MOUNTING THE SPEAKER — Cut a circular hole 1034 inches in diameter, Four
Va-inch mounting holes are provided on the outer periphery of the speaker frame.
Use four #12 x 116-inch long wood screws, or preferably drill four 1/-inch
holes on a 1115-inch circle spaced 90 degrees apart (See Fig. 3 for hole arrange-
ment), and employ four 3ig-inch carriage bolts 2 inches long with hex nuts and
washers. Secure the speaker to the front baffle, making certain that the VHF
driver horn slit has its long dimension vertical. This will insure widest dispersion
of the high frequencies in the horizontal plane. Tighten the retaining screws just
enough to compress the speaker gasket. Do not tighten too much or the frame
may be sprung out of line. This will damage the speaker unit,
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Drill a 34-inch hole nearby and mount the high-frequency level control. (Note:
The E-V Aristocrat enclosure has a predrilled hole for accepting the Brilliance
level control.) Insert the AT37 level control with the lugs toward the top. Re-
place the AT37 dial and affix it by tightening the lock nut with a pair of long-
nosed pliers. Replace the knob on the AT37 control and note to be certain
that the dot on the knob coincides with the zero on the dial at maximum clock-
wise rotation.
Beem OPERATION
| y CONNECTIONS — No. 22 fixture wire or larger can be used to connect the
| 12TRX and 12TRXB triaxial reproducers to the amplifier. The 12TRX has a
wiring harness, and the X36 and AT37 level controls should be connected as
Azer cos —, shown in Fig. 3. Connect the two terminals on the 12TRXB to the “16-ohm” and
Er Xe À “Common” output terminals on your amplifier. The 16-ohm impedance of the
| 12TRX and 12TRXB is a standard RETMA rating, A mismatch by as much as
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eto may be e without affecting the reproduction or efficiency of the unit.
Fig. 4 — Pictorial Wiring Diagram If only an 8-ohm tap is available on the amplifier, a loss of efficiency will be just
; ticeable. Co d 4- :
Model 12TRXB on Aristocrat Mounting Board Sugai nnected to a 4-ohm terminal, a loss of overall efficiency will be
AMPLIFIER DAMPING CONTROL SETTING—If your amplifier has a variable
damping control, as do all E-V units, set this control in accordance with the value
in the table of specifications.
THE BRILLIANCE CONTROL — Perfect adjustment to match the acoustic conditions
in any room may be made by proper setting of the brilliance control. Rooms
BASIC COAXIAL DRIYER SEPARATE SEPARATE
FULL-RANGE WITH SEPARATE 2-WAY J WAY having large amounts of overstuffed furniture or thick rugs, will require an
SYSTEM VHF DRIVER — SYSTEM SYSTEM advanced setting of the brilliance control of about 3/ clockwise rotation. Rooms
СР) Tr oR Ne, № or with little padded material or of small size will allow best musical balance when
the control is set at about 1% rotation. The correct position of the control for
any environment will be immediately apparent, bringing the highs and lows into
TRAE balance and making the sound come into “focus.”
TRIAXIAL
3WAY SYSTEMS
127R% E-Y “BUILDING BLOCK” METHOD
The E-V Aristocrat enclosure has precut holes and mounting facilities for future
expansion of the 12TRX system through the addition of the T25A midrange
E-V “Building-Block Method” Compatibility Chart ~~ driver with the 8HD hom, the X8 crossover, and the AT37 level control, if
further enhancement of midrange reproduction is desired. Such an addition is
not possible with the 12TRXB because of the integral arrangement of the
electrical crossover network.
Ey) ELECTRO-VOICE, INC. / BUCHANAN, MICHIGAN
Part No, 53343 Printed in U.S.A.
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DESCRIPTION
Incorporating all the design advantages of the famous
Electro-Voice Radax Coaxial principle, the Electro-Voice
Model 12TRXB integrated 3-way loudspeaker includes,
also, the latest developments in the reproduction of the
highest audible frequencies through the use of an integral
Super Sonax VHF driver. Bass response is excellent,
affording pleasing musical balance without the masking
effects previously experienced from extended high-
frequency reproduction.
The 12TRXB incorporates in the high-frequency section
the Sonophase throat design. Fig. No. 2 shows the
cross-section of a conventional high-frequency driver.
Response is flat up to 4 or 5 kHz, after which destructive
interference results from inability of the diaphragm to act
as a piston. Increasingly higher frequencies cause the
phase of sound produced at the diaphragm periphery to
shift with respect to sound produced by the diaphragm
center — this being due to diaphragm deformation (See
Fig. 3). In the Sonophase design, Fig. 4, sound from the
central portion of the diaphragm is delayed by the longer
path length, restoring proper phase relationship and level
as the frequency increases. The importance of the Sono-
phase throat design is paramount above 12 kHz, where
sound must be taken from the center of the diaphragm
and the periphery simultaneously.
Further benefits are afforded in the high-frequency
section of the Electro-Voice integrated 3-way speaker
systems by the incorporation of exclusive Electro-Voice
Diffraction Horns for maximum dispersion. In stereo-
phonic use especially, a 3 db concentration of sound in
one portion of the room is sufficient to cause an apparent
displacement of the subject, with the resultant distortion
of the solid or stereo effect.
An adjustable “brilliance” control is incorporated to
allow matching of response to room acoustics, compen-
sating for high-frequency absorptive effects of heavy
drapery and soft furnishings.
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Fig. | — Dimensions
SPECIFICATIONS
Frequency Response: 35 to 20,000 Hz
Electrical Crossover: Integral 3500 Hz
EIA Sensitivity Rating: 52 db
Power Handling Capacity,
Program Material: 30 watts
Peak: 60 watts
Nominal Impedance: 8 ohms
Voice Coil Diameter: Woofer, 2% in.
Tweeter, | in.
Woofer, 1 lb., 6 oz.
Tweeter, 3.16 oz.
Woofer, 10,000 G
Tweeter, 10,000 G
Size: 12% in. dia.
7 in. deep overall
Magnet Weight:
Flux Density:
Mounting: Four 9/32 in. holes
on 114 in. circle
Baffle Opening: 10% in.
Net Weight: | 1 Ibs.
Shipping Weight: | 4 Ibs,
INSTALLATION
As with any quality loudspeaker, care should be taken to
house the 12TRXB properly if best results are to be
obtained, Excellent results may be achieved by the use of
a properly designed bass reflex enclosure. Information on
home construction of bass reflex enclosures is available in
Technical Bulletin No. 10. Any of the bass reflex en-
closures described in numerous articles may be employed,
provided they are intended for a speaker of the same size
and resonant frequency as the 12TRXB.
Cut a baffle opening and drill mounting holes as indi-
cated. Use four carriage bolts, nuts and washers, or
equivalent; use of woodscrews is not recommended.
Secure the speaker to the baffle board just tightly enough
to compress the speaker gasket. Excessive tightening is
12TRXB INTEGRATED
3-WAY SPEAKER
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not necessary as the compressible gasket will form an
acoustical seal with nominal pressure.
Connections: No. 18 lamp cord or larger can be used to
connect the 12TRXB to the amplifier output terminals.
Note that the 12TRXB is equipped with three terminals,
two red and one black. For normal operation, the two
red terminals are connected together by a jumper wire.
Amplifier connections are then made to either one of the
red terminals and the black terminal. The 8 ohm im-
pedance of the 12TRXB is a standard nominal EIA
rating. A mismatch by as much as 40% may be made
without affecting the reproduction of the unit. A barely
noticeable loss of overall loudness will result from con-
nection to a 4-ohm tap.
Adjustment of Level Control: Perfect musical balance to
match the acoustic conditions in any room may be
achieved by the proper setting of the “brilliance” control.
Rooms having large amounts of overstuffed furniture or
thick rugs will require an advanced setting of the bril-
lance control of about 3/4 clockwise rotation (3/4 fully
open). Rooms with little absorptive material or of small
size and having high reverberation characteristics, will
give best musical balance when the control is set at about
half open. In order to achieve correct setting for a
particular room, rotate the control while playing a com-
prehensive musical passage and by careful listening, you
will have no difficulty in obtaining the correct balance —
the highs and lows will come into balance, placing the
sound “in focus”.
CAUTION NOTES
Power Handling Capacity: In program material feeding
through a 40-watt amplifier, only occasional peaks actual-
ly approach a full 40 watts. The average power is much
less throughout the musical range, Less than 3% of the
total energy in comprehensive musical passages lies above
3500 Hz. This energy is composed of transient signals
which are never sustained for long periods. Accordinely,
it will be seen that the loudest passages above 3500 Hz
seldom reach a total of one watt. The lowest frequency
reproduction recommended for the VHF driver in the
12TRXB is 3500 Hz, and attenuation below this point
should occur at the rate of at least 6 db per octave. This
attenuation is afforded by the crossover network integral
in the 12TRXB.
Test Precautions: A sustained tone above 3500 Hz from
an oscillator such as is used for test purposes may be
employed for short periods with up to 5 watts of power,
but after five minutes or so, tremendous heat builds up in
the sensitive driver and may damage the coil. For this
reason, such tests must be of short duration. Naturally,
sustained signals of this kind are never remotely ар-
proached in program material,
Precautions in Tape Machine Operation: If the speed of a
tape machine is advanced beyond the normal speed,
high-frequency power is quadrupled for each doubling of
tape speed. On fast forward or rewind supersonic energy
of great magnitude may be generated, even though the
head gate is open. Always reduce volume during this
process, even though the signal is inaudible. This is
especially important in fast editing procedures, where the
gate is frequently only partially opened so that the tape
traverse can be cued audibly.
Unstable Amplifiers: Supersonic oscillation may occur in
Diophrogm Assembl
Harn Action of diaphragm at higher frequencies.
Cotted ling shows departure from piston action.
Figure 3
Loading Plug
Sonophase Assembly Leoding Plug
Figure 2
Voice Coil Sound Chamber
Figure 4
an amplifier whereby high-power inaudible signals may
generate damaging heat in the driver units. Such oscilla-
tion may be detected with an oscilloscope, or by the
presence of heat in the driver unit by feeling the pot
structure of the driver. This can be corrected in some
cases by using low-capacity television twin-lead between
the amplifier and speaker system.
Changing Connections While Amplifier is On: Another
cause of excessive power application is the changing of
connections while the system is operating. The removal
or plug-in of à connector may generate a tremendous
surge up to the rated amplifier power. This will damage
sensitive VHF driver units, treble drivers, and sometimes
cone speakers. Defective switching units in the amplifier
can cause a similar effect.
Feedback: Acoustic feedback may be the result of a
speaker feeding back into a microphone, or it may be
caused by the oscillations given off by a “microphonic™
electronic component. Another common cause is the
mechanical vibration from a speaker adjacent to the
phono pickup or turntable. Feedback of this nature will
build up at a continuously accelerating rate until some
link in the reproducing chain fails, the amplifier “flat
tops”, or the power is reduced below the point of critical
excitation. Because damage to treble and VHF units may
occur, due caution should be exercised.
CUSTOMER SERVICE
The I2TRXB is packed to provide protection well in
excess of shipping requirements of the Interstate Com-
merce Commission. If shipping damage does occur, con-
tact the carrier or the dealer from whom the unit was
purchased and request inspection and instructions.
WARRANTY
Electro- Voice high fidelity speakers, speaker systems, and
accessories are guaranteed for five years from date of
original purchase against malfunction due to defects in
workmanship and materials. If such malfunction occurs,
unit will be repaired or replaced (at our option) without
charge for materials or labor if delivered prepaid to the
proper Electro-Voice service facility, Unit will be
returned prepaid. Warranty does not cover finish or
appearance items or malfunction due to abuse or
operation at other than specified conditions. Repair by
other than Electro-Voice or its authorized service
agencies will void this guarantee.
Part Number 534611 — 422
a Gulton com»anv ELECTRO -VOICE, Inc., 600 CECIL ST., BUCHANAN, MICH. 49107
MANUFACTURING PLANTS AT B BUCHANAN, MICH. B NEWPORT, TENN. B SEVIERVILLE, TENN. B GANANOQUE, ONT. BR LITHO IN U.5.A,