Electro-Voice TL880D User Manual
TL880D
Very-Low-Frequency
Speaker System
• Designed for cinema subwoofer use
• High acoustic output to below 20 Hz
• Two EVX-180A woofers provide very
high peak and long-term output that
complements the dynamic potential of
digital sound on film
• 2,000 watts continuous program
• Side-mounted connection panel
facilitates hookup when depth behind
the screen is restricted
• High output ability in the 20- to
40-Hz range is also ideal for
very-low-frequency synthesized
effects, down-tuned bass guitars
or pipe organ
• Approved for subwoofer use in THX
cinema systems*
®
Description and Applications
The Electro-Voice TL880D is a member of
the TL series of low-frequency enclosures.
The TL880D is a dual direct-radiating vented
design that provides high efficiency, low
distortion and excellent low-frequency
performance. The TL880D employs two
long-throw EVX-180A 18-inch loudspeakers, in an 15.5-ft
without grille. It is specifically designed to
meet the low-frequency demands of digital
cinema sound, in subwoofer applications.
The TL880D’s high pumping capability , high
acoustic output ability and extended bass
response (to below 20 Hz) make it particularly appropriate for the dynamic potential of the digital cinema application. (The
TL880D is approved for subwoofer use in
®
THX
cinema systems.)* The side-mounted
input panel facilitates behind-the-screen installation, where limited space between the
screen and theatre wall often makes it difficult to connect to the back of an enclosure.
The TL880D’s performance characteristics
also make it highly appropriate as the
subwoofer in large, multiway systems for
contemporary music playback and sound
reinforcement. The TL880D has more out-
_________________
*THX is a registered trademark of Lucasfilm Ltd.
3
, black-finished enclosure
put below 40 Hz than the devices typically
used in these applications.
Frequency Response
The TL880D’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.
Directivity
The directional characteristics of the
TL880D 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 AcoustaCADD
puter-aided 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
TL880D. The directivity factor R
TM
com-
(Q) is the
θ
relative value, at a point, of the TL880D
when compared to an ideal spherical
response. The directivity index, D
lated by D
Power Hanndling Capacity
T o our knowledge Electro-V oice 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.
= 10 log Rθ.
i
, is calcu-
i
TL880D Very-Low-Frequency Speaker System
Specifically, the TL880D is designed to withstand the power test described in ANSI/EIA
RS-426-A 1980. 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 proce-
TL880D Very-Low-Frequency Speaker System
dure provides a rigorous test of both thermal and mechanical failure modes.
The TL880D 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
operating in unison or “in phase.”) This principle is already employed in the dual-woofer
TL880D, 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 TL880D’s can be used side-by-side and
their combined performance will be different from that of a single TL880D in the ways
outlined below.
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 additional power capacity accounts for
the remaining 3 dB.
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:
rating.
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 Electro-Voice EX-24, XEQ-2
and XEQ-3 electronic crossover/equalizers
where D
the cones, and f (Hz) is the highest frequency
at which coupling occurs. When D
greater than one-quarter wavelength, which
would occur if two TL880D’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.
can provide the necessary subpassband protection. The 3-dB-down points are 30 Hz
(EX-24 and XEQ-2) 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
Cone loudspeakers may be stacked for
greater acoustic output and a narrower
Installation and Suspension of TL880D
Enclosures
The TL880D is designed for typical cinema
stage (behind-the-screen) applications where
subwoofers are mounted on the stage floor.
The TL880D is not designed to be self-suspended from above, and if suspended,
must be supported and hung in a way
which does not depend on the structure
of the TL880D itself for support.
beamwidth. (It is assumed that all cones are
3,000
f @ ————— ,
D
MAX
(inches) is the distance between
MAX
MAX
Architects' and Engineers'
Specifications
The loudspeaker system shall be a dual lowfrequency, bass-reflex design. Two 18-inch
woofers shall be front mounted in an 15.5-
3
ft
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 23 to 2,000
Hz; sensitivity, 98 dB at one watt, one meter ,
100 to 800 Hz, on axis; impedance (woofers
paralleled), 4 ohms nominal, 4.2 ohms minimum; dispersion angles 220° (horizontal) x
180° (vertical) at 200 Hz. The enclosure
shall be constructed of black texture-painted
poplar plywood . 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. An installed
vent cover shall be supplied that, when removed, shall raise the box tuning frequency
from 25 Hz to 30 Hz, for increased output in
the 30- to 40-Hz range. The enclosure dimensions shall be 47.5 in. high x 30.0 in.
wide x 23.8 in. deep (121 cm x 76.2 cm x
60.5 cm). Net weight shall be 160 lb (72.6 kg).
The low-frequency speaker system shall be
the Electro-Voice TL880D.
Uniform Limited Warranty
Electro-Voice products are guaranteed
is
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
W arranty 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
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