Electro-Voice TL880P User Information

Electro%ice@

TL880P

Very-Low-Frequency

Powered Speaker

System

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Digital Capable(TM) designed expressly to meet
the dynamic and low-frequency potential of
digital sound on film
THX approved’
Side-mounted connection panel facilitates
hookup when depth behind the screen is
restricted
Two

EVX-180A 18-inch

woofers, rated at 2,000

watts

of combined continuous program power,

provide

very

high

low-irequency

pumping ability

to

below 23 Hz

Unusually exlended

LF response also appropriate

for very-low-frequency synthesized

effects, down­tuned bass guitars or pipe organ
Internal,

P1250

power amp delivers 1,200

watts
continuous to the loudspeakers
On-board P1250 processing provides “step-down”
ED, limiting to prevent amp clipping under

high-

output conditions, and infrasonic speaker

protection

‘THX

is a registered trademark of Lucasfilm Ltd.

Description and Applications

The Electro-Voice

TL880P

is a member of
the TL series of low-frequency enclosures.
The TL880P is a powered subwoofer de­signed expressly for digital sound on film
and other applications which require very
high low-frequency pumping ability ex­tending to 25 Hz and below. The TL880P
features an Electra-Voice

P1250

power am­plifier, set up in bridge mode driving two
EVX-180A

457-mm

(1

8-in.) speakers, with
a combined rating of 2,000 watts continu­ous program, connected in parallel. The
P1250

can deliver 1.200 watts continuous

(20-20,000

Hz) to the resultant 4-ohm load.

The

P1250

has on-board signal processing

which supplies:

1. Low-frequency equalization nec­essary for “step-down” operation
of the loudspeaker system, pro­viding an overall system response
whose

3-dB-down

point (f,) is 23 Hz.

2. Infrasonic protection of the
EVX-

180A-s

below the

P1250’s

peak boost frequency of 26 Hz.

3. Output limiting that prevents ampli­fier clipping under high-output con­ditions.

The side-mounted input for the amplifier
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.

Directivity

In addition to motion-picture applications, the
TL880P

is highly appropriate as the subwoofer

in large,

multiway

systems for contemporary
music playback and sound reinforcement. The
TL88OP

has more output below 40 Hz than the

devices typically used in these applications, in

either the normal (25 Hz) or alternative
(30 Hz) box tuning (see Alternative Vent Tun­ing and Equalization Options section). Thus.
the

TL880P

is not only appropriate for the

more typical

40-Hz-and-above subwoofer

re­quirements, but also for those applications,
e.g., very-low-frequency synthesized effects
and down-tuned bass guitars, that require high
output below 40 Hz. This extended low-fre­quency performance also plumbs the depths
of the symphony orchestra and pipe organ.

The directional characteristics of the

TL88OP
were measured in Electro-Voice’s large
anechoic chamber; the test signal was

one­third-octave filtered pink noise at the fre­quencies indicated. A full spherical measure­ment system was used. All directional informa­tion was measured at 6.10 meters (20 feet).

Figure 2 illustrates the horizontal and verti­cal polar responses. Figure 3 shows the hori-

zontal and vertical beamwidths. Beamwidth
is the angle at which the horizontal and ver-

tical polar responses have decreased in level

by 6

dB

when compared to the axial fre-

quency response.
Figure 4 illustrates the total directivity of the

TL880P

The directivity factor R,(Q) is the

ratio of the SPL of the

TL880P

at a given
point to the SPL of an ideal omnidirectional
source at that same point. The directivity
index,

D,,

is calculated by D, = 10 log,,, R,.

Frequency Response

Power Handling

The

TL88OP’s

axial frequency response was

measured in

Electro-Voice’s

large

anechoic

cham-

ber at a distance of 3.05 meters (10 feet) with a

swept sine-wave input. Figure 1

1

has been aver­aged and corrected for 1 watt/l meter into the
transducers.

Electro-Voice

components and systems are
manufactured to exacting standards, ensur­ing they will hold up, not only through the

most rigorous of power tests, but also

through continued use in arduous, real-life
conditions. The eight-hour EIA Loudspeaker
Power Rating Full Range

(ANSI/EIA RS­426-A 1980) uses a noise spectrum which
mimics typical music and tests the thermal and
mechanical capabilities of the components.
Electra-Voice will support relevant additional
standards as and when they become avail­able. Extreme, in-house power tests, which
push the performance boundaries of the woof­ers, are also performed and passed to ensure
years of trouble-free service.

Specifically, the TL880P passes ANSI/EIA
RS-426-A 1980 with the following values:

R,,

=

4.80 ohms (1.15 x

RJ

P

E(MAX) =

1,200 watts

Test voltage = 75.9 volts rms,

15 1.8 volts peak

The “peak” power-handling capacity of a
woofer is determined by the peak test volt­age amount. For the

TL880P,

a

151.8-volt
peak test voltage translates into 4,800-watts
short-term peak power-handling capacity.

This is the equivalent of four times the “av­erage” power-handling capacity, and is a
peak that can be sustained for only a few
milliseconds. However, this sort of

short­duration peak is very typical in speech and
music. Provided the amplifier can reproduce
the signal accurately, without clipping, the
woofer will also perform accurately and re­liably, even at these levels.

Continuous program power is defined as 3

dB
above (double) the continuous sine-wave
power rating. The sine-wave power rating is
a two-hour test performed at the minimum
impedance of the system. It is included so
comparisons can be made with competitive
products.

Alternative Vent Tuning and
Equalization Options

The

TL880P

uses the on-board signal pro-

cessing of the

P1250

amplifier to provide
the required equalization for operating in the
“step-down” mode. This equalization reaches
a maximum of 6

dB

at 26 Hz and at 12 dB per

octave below this frequency (and at 24

dB

per
octave below 15 Hz). Overall system re­sponse is 3 dB down (f,) at 23 Hz. (Achiev­ing this same fR without equalization would
require twice the enclosure volume.) The

loudspeaker is shipped with its central port
cover in place to provide the appropriate,
25-Hz box tuning. This configuration must
be maintained for “as shipped” operation of
the

TL88OP.

The step-down mode maximizes
acoustic output ability at frequencies just
below 30 Hz (see Figure

1),

appropriate for

the

TL88OP’s

primary application as a cin-

ema very-low-frequency subwoofer.
If it is not desired to use the

TL88OP

in the
step-down mode, eliminating the need for
boost-and-cut equalization, it is necessary to
remove the central port cover. This moves
box tuning up to 30 Hz and also moves the
system f3 up to 30 Hz. See the

P1250

Set-

tings section for proper amplifier settings in

the normal mode.

Subpassband Speaker Protection

The

P1250

power amplifier provides

12-dB­per-octave infrasonic protection of the
EVX-18OA’s

below the

P125O’s

peak-boost
frequency of 26 Hz. Protection is increased
to 24

dB

per octave below 15 Hz.

P1250

Settings

The

TL880P

is shipped with the

P1250 rear­panel processor settings set for step-down
mode. See Figure 6. The speakers are con­nected to the central, bridged output. In the
event that the rear-panel settings are dis­turbed, the proper settings are noted below.
The rear panel of the

P1250

is easily acces­sible through the access/vent opening in the
speaker enclosure side closest to the top of
the amplifier:

Step-Down Mode Settings (as shipped):

1.

Limiter Time Constant switch: Slow.

2. Processor switch: B6.

3.

Pole Frequency switch: 26.

4.

Bridged Mode switch: Bridged.

5.

Hi-Low-Cut Filter switch: 15.

Normal Mode Settings:

1.

Limiter Time Constant switch: Slow.

2. Processor switch: Off.

3.

Pole Frequency switch: N/A

4.

Bridged Mode switch: Bridged.

5.

Hi-Low-Cut Filter switch: 31 Hz.

Use in Multiples

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
TL88OP,

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

TL880P’s

can be used side-by-side
and their combined performance will be dif­ferent from that of a single

TL880P

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 fre-

quencies whose wavelengths are longer that
one-quarter the center-to-center distance be­tween the cones. The highest frequency at
which mutual coupling occurs is calculated
from the following equation:

3,000

fG-,

D

MAX

where

D,,,

(inches) is the distance between
the cones, and f (Hz) is the highest frequency
at which coupling occurs. When

D,,,

is
greater than one-quarter wavelength, which
would occur if two

TL880P’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-han-

dling increase.

Service

In the unlikely event the

TL88OP

requires ser­vice, the woofer can be replaced or serviced
from the front and the amplifier can be re­placed or serviced from the top. A service
data sheet is available from Electro-Voice.