dual leveler/ limiter
Operating Instructions
DUAL LEVELER/ LIMITER
L-1102
TOA 1000 series
THE
LIGHTNING
FLASH
WITH
ARROWHEAD WITHIN A TRIANGLE IS
INTENDED TO TELL THE USER THAT
PARTS INSIDE THE PRODUCT ARE A
CAUTION
TO REDUCE THE RISK OF ELECTRICAL
SHOCK, DO NOT REMOVE COVER.
NO USER SERVICEABLE PARTS INSIDE.
REFER
SERVICING
TO QUALIFIED
SERVICE PERSONNEL
RISK
OF
ELECTRIC
SHOCK
TO
PERSONS.
THE EXCLAMATION POINT WITHIN A
TRIANGLE IS INTENDED TO TELL THE
USER THAT IMPORTANT OPERATING
AND SERVICING INSTRUCTIONS ARE
IN
THE
PAPERS
WITH
APPLIANCE.
Please follow the instructions in this manual to obtain the optimum results from this unit. We
also recommend that you keep this manual handy for future reference.
TOA Corporation
THE
Contents
Handling precautions
2
General description
2
Features
2
Nomenclature
Front panel
3
Rear panel
4
Connections
4
Operation
5
Matching transformer mounting
6
Block diagram
7
Appearance
7
Specifications
8
Accessories
8
Handling Precautions
1. Operating power voltage is local mains voltage plus or minus ten percent.
2. Keep chemical and beverages away from the unit.
3. To avoid severe electric shocks and possible catastrophic damage, always refer
servicing to qualified technical service personnel when component malfunctions occur.
General Description
The TOA L-1102 functions as a leveler or as a limiter, which can be selected with a switch.
It contains two leveler/limiter units (CH1 and CH2), and each channel is equipped with a
noise gate. The L-1102 is mountable in an EIA standard 19" rack (1-unit size).
Features
Dual leveler/limiter unit system. Either function can be selected for each unit with a
switch.
If the limiter is selected, speakers can be protected regardless of amplifier gain
because the power amplifier output is used as a sense input.
If the leveler is selected, an output level can be adjusted within the range of 0 dB ~20
dB.
Gain reduction meter to check the unit's operation.
Noise gate for each channel.
Electronically-balanced input and output. Optional transformers LT-101 (input) and LT102 (output) enable transformer-balanced input and output.
Security cover.
—2—
Nomenclature < Front Panel >
Noise Gate Switch and Gate Standby Indicator
Press this switch to put the noise gate in standby mode, and the standby indicator lights. To
disable the noise gate, press the switch again, and the indicator is extinguished.
Noise Gate Threshold Control
Sets up the threshold of noise gate input within the range of from -80 dB to -40 dB.
Noise Gate Indicator
Lights when an input signal level is lower than a predetermined threshold value, and is
extinguished when exceeding the threshold value.
Leveler/Limiter Select Switch and Selection Indicator
The switch selects either a leveler or a limiter. The leveler's indication lamp lights if the
leveler is selected, and the limiter's indication lamp lights if the limiter is selected.
Leveler/Limiter Threshold Control
Adjusts the leveler's threshold level within the range of from -40 dB to 0 dB, or the limiter's
threshold level from 1V to 100V rms.
Output Level Control
This control is effective only when the leveler is selected. It adjusts the output signal level
within the range of 0 dB~20 dB (from "0" to "10" in 2 dB steps).
Gain Reduction Meter
Indicates the output comperession with respect to the input for a maximum of 30 dB.
Bypass Switch and Bypass Indicator
When this switch is pressed, as indicated by its indicator, all input signals bypass the unit for
direct output.
Signal Indicator
Lights when an input signal level exceeds -30 dB.
Stereo Linkage Switch and Indicator
Press this switch (its indicator lights) when stereo L and R signals are input into both
channels, CH1 and CH2.
Operation of both channels depends on the leveler/limiter threshold control setting for CH 1.
All other switches and controls can be used independently for operation of each channel.
[Note] : For stereo applications, the same function (i.e. either a leveler or limiter) must be
selected for both channels.
Power Switch and Indicator
Press this switch to turn power ON (indicator lights). To turn power OFF, press this switch
again (indicator is extinguished).
Security Cover Mounting Hole
Used to mount the security cover with the supplied screws to avoid accidental changes in
control and switch settings.
—3—
Nomenclature < Rear Panel >
AC Fuse Holder
When replacing, be sure to use the fuse of specified rating and type to avoid the possibility
of fire.
AC Power Cord
Plug this cord into the wall AC outlet.
Ground Screw Terminal
Hum can result from a ground loop to be formed when the L-1102 is connected to other
equipment. In such cases, cut the loop by removing a shorting piece. Usually, mount the
shorting piece to the terminal.
Sense Input Screw Terminal
Connect this terminal to the power amplifier output of each channel when in "limiter" mode.
See to it that the polarities of power amplifier output and sense input terminal are matched.
Output Screw Terminal
The output terminal is electronically-balanced. Place the supplied shorting piece between E
and C to convert into unbalanced type.
Input Screw Terminal
The input terminal is electronically-balanced. Place the supplied shorting piece between E
and C to convert into unbalanced type.
Connection Examples
1. If using as a leveler
2. If using as a limiter
To mixer,
Power amp.
input
Speaker
output
To mixer,
preamplifier,
etc.
Power amp.
input
preamplifier,
etc.
Speaker
output
1000 series
Power amplifier
1000 series
Power amplifier
Speaker
Speaker
—4—
Operation
Leveler/Limiter Threshold Setting
POWER
AMP
OUTPUT
1. Limiter (Speaker protection)
Power amplifier output is input into the sense input screw terminal as a sense signal. If the
sense signal level exceeds a predetermined threshold value, the limiter compresses the
output.
As can be seen from a compression curve in the figure below, the output amplitude is linear
with respect to the input up to the threshold (A) and gentle and constant thereafter for
compression in the ratio 10 (input) to 1 (output). (The leveler/limiter threshold control knob
points to the threshold A.)
INPUT
OUTPUT
2. Leveler
If the input signal level exceeds a predetermined threshold value, the output is compressed.
The overall output level can be adjusted within the range of 0 dB~20 dB ("0"~"10" in 2 dB
steps) using the output level control.
INPUT
—5—
Matching Transformer Mounting
CAUTIONS
THESE SERVICING INSTRUCTIONS ARE FOR USE BY QUALIFIED PERSONNEL ONLY. TO
AVOID ELECTRIC SHOCK DO NOT PERFORM ANY SERVICING OTHER THAN THAT
CONTAINED IN THE OPERATING INSTRUCTIONS UNLESS YOU ARE QUALIFIED TO DO
SO. REFER ALL SERVICING TO QUALIFIED SERVICE PERSONNEL
The L-1102's input and output are electrically balanced. These can be converted to
transformer balanced types using the optional matching transformer LT-101 (input) and
LT-102 (output).
1. Set the power switch to OFF and unplug the AC cord from a wall outlet.
2. Remove ten side panel screws to remove the case.
3. For input conversion, first fix two sleeves (supplied with the transformer) to the lefthand side, as viewed from the front, by tightening two screws from the outside of a
bottom chassis, and then place the input transformer on the sleeves and fix it using
two screws. See Fig. 1. After installing the transformer, detach connector CN35 from
CN1, reconnect it to connector (a) at the transformer side, and connect connector (b)
coming from the transformer to CN1, as shown in the figure.
4. Similarly, install the output transformer at the right-hand side for output conversion.
And then, detach connector CN2 from CN36, reconnect it to connector (c) at the
transformer side, and connect connector (d) coming from the transformer to CN36.
Fig.1
5. Replace the case.
[Note] :
(1) Follow the same procedure as the above to enable transformer-balanced input and
output for channel 2.
(2) When installing the transformer, never touch other internal components other than
those described above as severe electric shocks may result.
Transformer Specifications
Model
LT-101
LT-102
30Hz~20kHz(±0.15dB)
30Hz~20kHz(±0.15dB)
Impedance
Frequency response
Constant loss
Distortion
Within 1.5dB (1kHz)
Within 1.5dB (1kHz)
Under 0.2% (+5dB*, 50Hz)
Under 0.2% (+5dB*, 50Hz)
0dB = 0.775V RMS
Specifications are subject to change without notice.
—6—
Block Diagram
Appearance
Unit
—7—
mm (in.)
Specifications
Power Requirements
AC Mains, 50 Hz/60 Hz
Power Consumption
14W (120V AC version)
15W (220/240V AC version)
Frequency Response
20~20kHz (±1 dB)
Total Harmonic Distortion
Under 0.1% (1 kHz, rated output)
Under 0.2% (1 kHz, 30 dB compression)
Input
+4 dB* for
load
(electronically balanced)
Output
+ 4 dB* for
load
(electronically balanced)
Maximum Input Level
+ 20 dB*
Maximum Output Level
+ 20 dB*
Threshold Level Range
Leveler: —40 to 0 dB*
(with respect to input)
Limiter: 1~100V rms
(with respect to sense input)
Noise Gate Threshold Range
—80 to —40 dB*
Adjustable Output Range
0 to +20 dB
Attack Times
Dependent on input (or sense input) signal
Release Times
Dependent on input (or sense input) signal
Finish
Black
Dimensions
482.6(W)X44.0(H)X316.8(D) mm
[19.00X1.73X12.47 in.]
Weight
4kg (8.8 Ib.)
Sense Input
0dB = 0.775V RMS
(electronically balanced)
Noise Level
Specifications are subject to change without notice.
Under —92 dB* (IHF-A)
Accessories
Security cover
1
Security cover mounting screws
2
Fuse 250V 0.3A (120V AC version)
1
Fuse 250V T100mA 220/240V AC version)
1
Shorting pieces
4
Operating instructions
1
Rack mounting screws
4
TOA Corporation
KOBE, JAPAN
133-12-110-00
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