TL550D - Bosch Security Systems Ltd.

Low-Frequency Speaker
• Designed for cinema stage use
(behind the screen)
• Extended, 40-Hz response (f3)
• Two EVX-150A woofers provide very
high peak and long-term output that
complements the dynamic potential
of digital sound on film
• Use as primary low-frequency
source in two-way systems or as
the sub-woofer in multiway systems
• 2,000 watts continuous program
• Side-mounted connection panel
facilitates hookup when depth
behind the screen is restricted
• 28-Hz f3 in step-down, ideal for
very-low-frequency synthesized
effects, down-tuned bass guitars or
pipe organ
• Optional HS6 or HS7 hanging kits—
through-the-box steel tubes provide
safe suspension
Description and Applications
The Electro-Voice TL550D is a member of
the TL series of low-frequency enclosures.
The TL550D is a dual direct-radiating vented
design that provides high efficiency, low distortion and excellent low-frequency performance in a compact enclosure. The TL550D
employs two long-throw EVX-150A 15-inch
loudspeakers, in an 8.4-ft3, black-finished
enclosure without grille. It is specifically
designed to meet the low-frequency demands
of digital cinema sound, in stage (behindthe-screen) applications. The TL550D’s high
pumping capability, high acoustic output
ability and extended bass response (40-Hz
3-dB-down point) make it particularly appropriate for the dynamic potential of the
digital cinema application. The side-mounted
input panel facilitates behind-the-screen installation, where limited space between the
screen and the theatre wall often makes it
difficult to connect to the back of an enclosure.
The TL550D’s performance characteristics
also make it highly appropriate as the primary low-frequency source in extended-response/high-output two-way speaker systems in a variety of other venues, including
auditoriums, theaters, performing arts centers, night clubs, concert halls and churches,
or as the subwoofer in large, multiway systems. In subwoofer use, the TL550D’s 40Hz 3-dB-down point is appropriate for most
contemporary music playback and sound reinforcement. In the “step-down mode,” the
TL550D’s f3 is lowered to 28 Hz, which
makes it appropriate for very-low-frequency
synthesized effects, down-tuned bass guitars,
and approaches the depths of the symphony
orchestra and pipe organ. (See Step-Down
The TL550D can be used with an externally
mounted XEQ-504 crossover/equalizer.
Thus, combined with appropriate ElectroVoice TransPlanar TM constant-directivity
high-frequency horns and DH1A, DH2A or
N/DYM®1 compression drivers, the TL550D
forms passive two-way systems with unprecedented wide-range frequency response and
high linearity. To extract even greater performance from the TL550D, a biamp configuration using the Electro-Voice XEQ-2 or
XEQ-3 crossover/equalizer is recommended,
allowing full rated power to be applied to
the low-frequency system.
Two optional horn-mounting kits are available for the Electro-Voice HP940 and
HP9040 horns. (See High-Frequency Horn
Mounting section.)
Frequency Response
The TL550D’s axial frequency response was
measured in Electro-Voice’s large anechoic
chamber at a distance of 10 feet with a swept
sine-wave input of 4 volts. Figure 1 has been
averaged and corrected for 1 watt/1 meter.
TL550D Low-Frequency Speaker System
TL550D Low-Frequency Speaker System
The directional characteristics of the
TL550D were measured in Electro-Voice’s
large anechoic chamber; the test signal was
one-third-octave filtered pink noise at the
frequencies indicated. A full spherical measurement system was used, which is compatible with the AcoustaCADDTM computeraided design program. All directional information was measured at 20 feet.
Figure 2 illustrates the horizontal and vertical polar responses. Figure 3 shows the horizontal and vertical beamwidths. Beamwidth
is the angle at which the horizontal and vertical polar responses have decreased in level
by 6 dB when compared to the axial frequency response.
Figure 4 illustrates the total directivity of the
TL550D. The directivity factor Rq (Q) is the
relative value, at a point, of the TL550D
when compared to an ideal spherical
response. The directivity index, Di, is calculated by Di = 10 log Rq.
Power Handling Capacity
To our knowledge Electro-Voice was the first
U.S. manufacturer to develop and publish a
power test closely related to real-life conditions. A random noise input signal is used
because it contains many frequencies simultaneously, just like real voice or instrument
program. The signal contains more energy
at extremely high and low frequencies than
typical actual program, adding an extra margin of reliability. The test combines not only
the overall long-term average or continuous
level—which our ear interprets as loudness—but also short-duration peaks which
are many times higher than the average, just
like actual program. The long-term average
level stresses the speaker thermally (heat).
The instantaneous peaks test mechanical reliability (cone excursion). Note that the sinewave test signals sometimes used have a
much less demanding peak value relative to
their average level. In actual use, long-term
average levels exist from several seconds on
up. We test for several hours, adding another extra level of reliability.
Specifically, the TL550D is designed to withstand the power test described in EIA Stan2
dard RS-426A. The EIA test spectrum is
applied for eight hours. The spectrum is obtained by filtering white noise (a particular
type of random noise with equal energy per
bandwidth). The filter applies a 6-dB-peroctave slope below 40 Hz and above 318 Hz.
When measured with a one-third-octave constant-percentage analyzer, this filter produces
a spectrum whose 3-dB-down points are at
100 Hz and 1,200 Hz with a 3-dB-per-octave slope above 1,200 Hz. This shaped signal is fed to the power amplifier with the
continuous power set to provide 1,200 watts
into the 4.8-ohm EIA equivalent impedance
(75.9 volts rms).
Amplifier clipping sets instantaneous peaks
at 6 dB above the continuous power, or 4,800
watts peak (151.8 volts peak). This procedure provides a rigorous test of both thermal
and mechanical failure modes.
The TL550D has also been power tested with
a two-hour sine wave, at minimum impedance, so that competitive comparisons can
be made using consistent methods. Continuous program power is defined as 3 dB above
(double) the continuous sine-wave power
an underdamped second-order high-pass filter tuned to 29 Hz with a Q of 2. This provides a boost of 6 dB at the tuning frequency
and a 12-dB-per-octave roll-off below. This
filter is directly available on the XEQ-2 or
can be generated in the XEQ-3 by using the
optional EB29/35 EQ module.
Subpassband Speaker Protection
Below the enclosure tuning frequency, cone
excursion increases rapidly. Since acoustic
output is also falling rapidly, there is no utility in driving the system with signals much
below tuning frequency. While such signals
may be in the program material, they are often extraneous, such as a dropped microphone. The step-down equalization described
in the Step-Down section provides the required protection. If step-down mode is not
used, the Electro-Voice EX-24, XEQ-2 and
XEQ-3 electronic crossover/equalizers can
also provide subpassband protection. The 3dB-down points are 30 Hz (EX-24 and XEQ2) and 16 Hz or 32 Hz (XEQ-3).
Other high-pass filters are available and onethird-octave equalizers can also be effective
at providing the required protection.
Use In Multiples
Step-down is a method of extending the lowfrequency response by increasing the power
input to the system instead of the enclosure
volume. In step-down mode, the enclosure
is tuned at a lower-than-normal frequency.
This increases the output at the new tuning
frequency and reduces the output at the original tuning frequency. This smoothly falling
amplitude response can be equalized to obtain a new 3-dB-down point in the region of
0.7 that of the original. To obtain a similar
response without step-down would require
an enclosure with at least twice the volume.
Cone loudspeakers may be stacked for
greater acoustic output and a narrower
beamwidth. (It is assumed that all cones are
operating in unison or “in phase.”) This principle is already employed in the dual-woofer
TL550D, and is responsible for the higher
sensitivity and narrower vertical beamwidth
(with the system long axis vertical) relative
to similar single-woofer systems. In addition,
two TL550D’s can be used side-by-side and
their combined performance will be different from that of a single TL550D in the ways
outlined below.
Step-down can be instigated by using the
supplied port cover. The enclosure tuning
will be lowered from 42 to 30 Hz.
At relatively low frequencies, below about
150 Hz for typical TL series dimensions,
stacking produces additional acoustic output
without altering dispersion. When a common
signal is applied, a 6-dB increase in maximum acoustic output occurs. The cones “mutually couple” and act as one cone with twice
the area (therefore twice the efficiency) and
twice the power capacity. The additional
cone area provides 3 dB more output and the
If an appropriate low-frequency boost-andcut equalization is applied, the normal f3 of
40 Hz is reduced to 28 Hz. It is suggested
that the Electro-Voice XEQ-2 or XEQ-3 active crossover be used to provide the required
equalization. The suggested equalization is
TL550D Low-Frequency Speaker System
additional power capacity accounts for the
remaining 3 dB.
f @ ————— ,
where DMAX (inches) is the distance between
the cones, and f (Hz) is the highest frequency
at which coupling occurs. When DMAX is
greater than one-quarter wavelength, which
would occur if two TL550D’s were widely
spaced, or at frequencies much above f even
when closely spaced, the increase in acoustic output is limited to the 3-dB power-handling increase.
At frequencies above the mutual coupling
limit, f, stacking alters dispersion and increases on-axis sensitivity. In the 500-to-800Hz range, a common crossover frequency for
two-way sound reinforcement systems, two
nearly adjacent cones have a coverage angle
about half that of either cone alone. This is
useful, for example, in more closely matching the typical 40° vertical dispersion of a
high-frequency horn. (At frequencies much
above 800 Hz, the concept of a halved coverage angle no longer applies, since the side
lobes, which result from two sources that are
not mutually coupled, increase in number and
approach or equal the main lobe in amplitude. The number of lobes and their amplitude increases as frequency increases.)
The optional HMK-1 and HMK-2 horn
mounting kits are available for use, respectively, with the Electro-Voice HP940 smallformat and HP9040 large-format constantdirectivity horns. The kits are designed to
facilitate fixing and aiming the high-frequency horn and driver on top of a vertically
oriented TL550D, in cinema stage (behindthe-screen) applications. This configuration
may be useful in a number of other applications as well. Refer to the individual HMK1 and HMK-2 engineering data sheets for
details and instructions.
The TL550D is designed for typical cinema
stage (behind-the-screen) applications where
low-frequency systems are mounted on platforms, behind the screen and some distance
above the stage floor. The TL550D is not
designed to be self-suspended, and if suspended, must be supported and hung in a
way which does not depend on the structure of the TL550D itself for support.
The HS6 and HS7 kits allow the TL550D to
be hung safely in a variety of orientations.
The combination of the correct HS kits and
TL550D enclosure has been certified by an
independent structural engineer to be safe
and secure. Each HS kit consists of a steel
tube, two brackets, two eyebolts and the necessary fasteners. The installer must assemble
the HS kit by first drilling two holes into the
TL550D enclosure, in predefined positions,
and then screwing the brackets onto the steel
tube, which passes through the enclosure. An
eyebolt is inserted in the T-nut in the rear
panel of the enclosure to provide a “pull up”
to aim the enclosure. Full instructions and
hole locations are included with each cabinet and HS kit. A TL550D requires a single
HS6 to suspend it horizontally, or a single
HS7 to suspend it vertically. Electro-Voice
recommends that only one TL550D be suspended at one time in this manner. Vertical
is defined as having the long side vertical.
Full attention must be given to the instructions and limitations in the HS kit instruction sheet.
Architects’ and Engineers’
The loudspeaker system shall be a dual lowfrequency, bass-reflex design. Two 15-inch
woofers shall be front mounted in an 8.4-ft3
enclosure. The system shall meet the following criteria: power handling, 1,200 watts of
pink noise with a 6-dB crest factor; frequency
response, smooth and uniform, usable at high
output levels from 40 to 2,000 Hz; sensitivity, 100 dB at one watt, one meter, 100-800
Hz, on axis; impedance 4 ohms nominal, 4.2
ohms minimum; dispersion angles 120°
(horizontal) x 55° (vertical) at 500 Hz. The
enclosure shall be constructed of black vinyl-clad particle board. The enclosure will
contain sound-absorbing glass wool. Each
woofer shall have the capacity to be fed independently of the other. The input panel and
connectors shall be side-mounted. The enclosure top panel shall be fitted with T-nuts
that accept the optional Electro-Voice HMK1 and HMK-2 horn mounting kits. A port
cover shall be included to enable “stepdown” operation for enhanced low-frequency performance. The enclosure dimensions shall be 39.5 in. high x 22.5 in. wide x
21.8 in. deep (100.3 cm x 57.2 cm x 55.4
cm). Net weight shall be 144 lb (65.5 kg).
The low-frequency speaker system shall be
the Electro-Voice TL550D.
Limited Warranty
Electro-Voice products are guaranteed
against malfunction due to defects in materials or workmanship for a specified period,
as noted in the individual product-line
statement(s) below, or in the individual product data sheet or owner’s manual, beginning
with the date of original purchase. If such
malfunction occurs during the specified period, the product will be repaired or replaced
(at our option) without charge. The product
will be returned to the customer prepaid. Exclusions and Limitations: The Limited
Warranty does not apply to: (a) exterior finish or appearance; (b) certain specific items
described in the individual product-line
statement(s) below, or in the individual product data sheet or owner’s manual; (c) malfunction resulting from use or operation of
the product other than as specified in the
product data sheet or owner’s manual; (d)
malfunction resulting from misuse or abuse
of the product; or (e) malfunction occurring
at any time after repairs have been made to
the product by anyone other than ElectroVoice Service or any of its authorized service representatives. Obtaining Warranty
Service: To obtain warranty service, a customer must deliver the product, prepaid, to
Electro-Voice Service or any of its authorized service representatives together with
proof of purchase of the product in the form
of a bill of sale or receipted invoice. A list of
authorized service representatives is avail-
TL550D Low-Frequency Speaker System
Specifically, mutual coupling occurs at frequencies whose wavelengths are longer than
one-quarter the center-to-center distance
between the cones. The highest frequency at
which mutual coupling occurs is calculated
from the following equation:
Installation and Suspension of TL550D
TL550D Low-Frequency Speaker System
TL550D Low-Frequency Speaker System
able from Electro-Voice Service at 600 Cecil
Street, Buchanan, MI 49107 (800/234-6831
or FAX 616/695-4743). Incidental and
Consequential Damages Excluded: Product repair or replacement and return to the
customer are the only remedies provided to
the customer. Electro-Voice shall not be liable for any incidental or consequential damages including, without limitation, injury to
persons or property or loss of use. Some
states do not allow the exclusion or limitation of incidental or consequential damages
so the above limitation or exclusion may not
apply to you. Other Rights: This warranty
gives you specific legal rights, and you may
also have other rights which vary from state
to state. Electro-Voice Speakers and
Speaker Systems are guaranteed against
malfunction due to defects in materials or
workmanship for a period of five (5) years
from the date of original purchase. The Limited Warranty does not apply to burned voice
coils or malfunctions such as cone and/or coil
damage resulting from improperly designed
enclosures. Electro-Voice active electronics
associated with the speaker systems are guaranteed for three (3) years from the date of
original purchase. Additional details are included in the Uniform Limited Warranty
For warranty repair or service information, contact the service repair department
at: 616/695-6831 or 800/685-2606.
For technical assistance, contact Technical
Support at 800/234-6831 or 616/695-6831,
M-F, 8:00 a.m. to 5:00 p.m. Eastern Standard Time.
Specifications subject to change without
FIGURE 1—Axial Frequency Response
(anechoic environment, 1 watt/1 meter)
FIGURE 2—TL550D One-ThirdOctave Polar Responses (anechoic
TL550D Low-Frequency Speaker System
FIGURE 3—TL550D One-ThirdOctave Beamwidth vs Frequency
(anechoic environment)
FIGURE 4—TL550D One-ThirdOctave Directivity vs Frequency
(anechoic environment)
TL550D Low-Frequency Speaker System
FIGURE 5—TL550D Harmonic
Distortion, 0.1 Rated Power Input
(120 watts), 10 Feet on Axis
FIGURE 6—TL550D Harmonic
Distortion, 0.01 Rated Power Input
(12 watts), 10 Feet on Axis
TL550D Low-Frequency Speaker System
400-800 Hz Horizontal:
TL550D Low-Frequency Speaker System
Frequency Response, 1 Watt at 1 Meter on
Axis, Swept One-Third-Octave Pink Noise,
Anechoic Environment (see Figure 1):
40-2,000 Hz
120° ± 10°
400-800 Hz Vertical:
60° ± 20°
Low-Frequency 3-dB-Down Point,
Directivity Factor Rq (Q), Median over Indicated Range (see Figure 4),
90-125 Hz:
40 Hz
Net Box Volume:
238 l (8.4 ft3)
Box Tuning Frequency,
400-800 Hz:
28 Hz
(10-dB-down point),
Two EVX-150A
42 Hz
Step-Down (with equalization):
Transducer Complement:
30 Hz
Directivity Index Di (10 log Rq),
Step-Down Peak-Boost Frequency (see
Step-Down section):
90-125 Hz:
32 Hz
0.0 dB
30 Hz
Step-Down (with equalization):
22 Hz
Impedance, Nominal/Minimum (see Electrical Connections section):
400-800 Hz:
4.0/4.2 ohms
9.6 dB
Distortion, 0.1 Full Power Input
Input Connectors:
Half-Space Reference Efficiency:
(see Figure 5),
Second Harmonic,
Side-mounted screw terminals (#10) on
barrier strip
(see Power Handling section),
Long-Term Average per EIA RS-426A:
1,000 Hz:
1,200 watts
Continuous Program:
2,000 watts
Maximum Long-Term Average Mid-Band
Acoustic Output:
89 watts
Enclosure Materials and Finish:
100 Hz:
100 Hz:
Optional Horn Mounting Kits:
1,000 Hz:
Distortion, 0.01 Full Power Input
100-800 Hz:
Second Harmonic,
Dispersion Angle Included by 6-dB-Down
Points on Polar Responses, Indicated OneThird-Octave Bands of Pink Noise (see Figure 3),
90-125 Hz Horizontal and Vertical:
HMK-1 and HMK-2 (can be used with the
HP940 and HP9040 horns, respectively)
(see Figure 6),
39.5 in. (100.3 cm)
100 Hz:
22.5 in. (57.2 cm)
50-125 Hz:
95 dB
Suspension (see Installation and Suspension
of TL550D Enclosures section):
Two “independently certified” suspension
kits are available, the HS6 and HS7
Third Harmonic,
Sound Pressure Level at 1 Meter, 1 Watt
(2.0 volts) Input, Anechoic Environment,
Band-Limited Pink-Noise Signal,
100 dB
Black vinyl-clad particle board
1,000 Hz:
Third Harmonic,
21.8 in. (55.4 cm)
Net Weight:
59.1 kg (130 lb)
100 Hz:
Shipping Weight:
65.5 kg (144 lb)
1,000 Hz:
600 Cecil Street, Buchanan, MI 49107
616/695-6831, 616/695-1304 Fax
SPEAKERS—Low-Frequency Systems
©EVI Audio 1999 • Litho in U.S.A.
Part Number 532030 —9943