How it Works
Lectrosonics
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LCA16
User Manual
18 pgs668.94 Kb0

Lectrosonics LCA16 User Manual

LCA16
LOGIC CONTROLLED AMPLIFIER*
OPERATING INSTRUCTIONS
and trouble-shooting guide
LECTROSONICS, INC.
* US PATENT NUMBER 5204908
Rio Rancho, NM
INTRODUCTION
The LCA16, in conjunction with an automatic mixer (such as the Lectrosonics Modular Audio Processor system) controls the gain of each speaker, individually, in response to activity on any of the microphones in the sound system. Any speaker can be attenuated or turned off completely by the logic output signals from the automatic mixer channels. In addition, each channel includes a balanced line level output which may be used to drive external amplifiers.
Each of the 16 output channels in the LCA16 provides 5 Watts into a 4 Ohm speaker (3 Watts into an 8 Ohm speaker) and a balanced line output. A straight forward switch matrix allows each individual output channel to be attenuated by any combination of the 16 logic inputs.
The LCA16 has integral power supplies and is designed for mounting in a standard 19-inch equipment rack. Three front panel LEDs per channel indicate the level of attenuation. The switch matrix and attenuation level controls are located behind a removable panel to prevent tampering or accidental mis-adjustment.
TABLE OF CONTENTS
INTRODUCTION .......................................... 1
GENERAL TECHNICAL DESCRIPTION .......................... 2
CONTROLS AND FUNCTIONS - FRONT PANEL ................... 3
CONTROLS AND FUNCTIONS - REAR PANEL .................... 5
PRE-CONFIGURING THE LCA16 PRIOR TO INSTALLATION,
16 or FEWER MICS PER LCA16 ............. 6
PRE-CONFIGURING THE LCA16 PRIOR TO INSTALLATION,
MORE THAN 16 MICS PER LCA16 ............ 8
INSTALLATION ........................................... 10
SYSTEM ADJUSTMENT ..................................... 12
SPECIFICATIONS ......................................... 13
SERVICE AND REPAIR ..................................... 14
RETURNING UNITS FOR REPAIR ............................. 14
APPENDIX 1 - POWER LOSS vs CABLE RUN .................... 15
APPENDIX 2 - LCA16 SYSTEM WORKSHEET .................... 16
WARRANTY ........................................ Back cover
1
GENERAL TECHNICAL DESCRIPTION
DIFFERENTIAL
L O G
I
C
I N P U
T
S
"A"
ATTENUATION
"B"
ATTENUATION
ATTENUATION
NO
ATTENUATION
"B"
ATTENUATION
"A"
ATTENUATION
NO
PWR AMP
SPKR +
SPKR -
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
16 LINES
16 LINES 16 LINES
TO CHANNELS 2 THROUGH 16
MAIN LEVEL
L O G IC S IG N A L CO N D IT IO NIN G L O G IC S IG N A L CO NDIT IO N IN G
LINE OUT -
LINE OUT +
GROUND
BALANCED LINE DRIVER
ATTENUATION
SELECT LOGIC
AND
LED DRIVERS
"A"
ATTENUATION
"B"
SELECT SWITCHES
ATTENUATION
SELECT SWITCHES
FRONT PANEL
LEDs
CH. 1
TO CHANNELS 2 THROUGH 16
AUDIO
BALANCED
INPUT
AUDIO
THROUGH
OUTPUT
INPUT
AMPLIFIER
SIGNAL PRESENT
In the following illustration is a simplified block diagram of the LCA16 showing one amplifier channel. All channels are identical.
The audio input of the LCA16 is an RF filtered, electronically balanced differential amplifier. An AUDIO THRU output is provided so the audio signal can be "daisy chained" to other devices if required. A SIGNAL PRESENT LED on the front panel indicates the presence of signal above -20dBv. The audio signal passes through the MAIN LEVEL control before being distributed to the output channel amplifiers. Each output channel employs a dedicated power amplifier. The amplifiers are fully protected from short circuits, thermal overloads or highly reactive loads. Each amplifier is individually fused, so in the event of catastrophic failure of any single channel, no other channels will be affected. Each output channel also includes a balanced line level output which is simultaneously available to drive external amplifiers, or other audio equipment.
The logic input signal conditioning circuits are specially designed to accept a wide variety of logic signals, ranging from relay contact closures to TTL logic levels. Each logic input passes through a time constant circuit with hysteresis. This guarantees minimum "signal chopping" caused by changing attenuation during pauses in speech. Photo-conductive opto-isolators are employed to switch the level of attenuation of the audio. These devices eliminate the abrupt audible changes that occur when hard switching is used.
Figure 1 - LCA16 Block Diagram
2
CONTROLS AND FUNCTIONS - FRONT PANEL
0
1
2
3
4
5
6
7
8
9
LECTROSONICS, INC.
LOGIC CONTROLLED AMPLIFIER
AUTOMATIC SPEAKER / LINE OUTPUT CONTROL
PO W E R
SI G N AL PR ESEN T
PO W E R
MA I N L EVEL
10
ATTE NUATION MODE
LCA16
CH . 3
ON A B
ATTE NUATI ON
CH. 4
ON A B
A TTE NU A TIO N
CH. 7
ON A B
ATTENU ATIO N
CH. 8
ON A B
ATTE NUA T ION
CH. 11
ON A B
ATTE NUATIO N
CH. 1 2
ON A B
ATTE NUA TIO N
CH. 14
ON A B
ATTE NUATIO N
CH. 16
ON A B
ATTE NUA TIO N
ON A B
ATTENUA TI ON
CH . 1
ON A B
ATTE N UA T IO N
CH. 2
ON A B
ATT E NUAT IO N
CH. 5
ON A B
ATTENUATION
CH. 6
ON A B
ATTE NUATIO N
CH. 9
ON A B
ATTE NUATI ON
CH. 1 0
ON A B
ATTE NUA T I ON
CH. 13
ON A B
ATTE NUAT ION
CH. 15
POWER SWITCH
Controls the application of AC power to the LCA16.
POWER LED
Indicates the presence of AC power to the LCA16.
MAIN LEVEL
Controls the overall output level of the sound system.
SIGNAL PRESENT LED
Indicates the presence of audio signal to the LCA16.
ON LED
(Channels 1-16) Indicates the output channel is in the "on" state (not attenuated).
ATTENUATION LEDS
A LED: (Channels 1-16) Indicates the output channel is at the "A" attenuation level. B LED: (Channels 1-16) Indicates the output channel is at the "B" attenuation level.
Figure 2 - LCA16 Front Panel
3
ATTENUATION DIP SWITCHES (located behind front panel cover)
SWITCH NUMBERS
ATTENUATION CONTROL POTS
3A
1
1
1
0
5
1
1
2
2 2
9
2
2
3
O
3
O
3
15
O
3
O
3
P
P
P
P
E
E
E
E
DIP SWITCHES
4 4 4
4
4
N
5
5
N
5
3B
N
5
N
5
6
6 6
6
6
0
5
9
7
7 7
7
7
8 8 8
15 8
8
9
1
1
0
5
1
1
10
2
2
9
2
2
11
O
3
O
3
O
3
O
3
12
4 4
4A
4 4
15
P
P
P
P
E
E
E
E
13
N
5
N
5
N
5
N
5
0
5
4B
14
6 6
6 6
15
7 7
9
7 7
16
8 8
15
8 8
3A
1
1
0
5 1
1 1 1
1
0
5 1
1
1
3A
3A
1
1
0
3A
5 1
1
1
1
1
0
5 1
1
2
2 2
9
2
2
2
2
2
9
2
2 2
9
2
2
2
2 2
9
2
2
2
O 3O
3
15
O 3O 33O
3O 3
15
O
3O 3
3
O
3
P
O
3
15
O
3
P
O
3
3
O P
3
O P
3
15
O P
3
O P
3
P
P
P P
P P
P
P
P
4 4
P
4
4
4
4
4
4
4
E
4 4
4
E
4 4
4
E
4
E
4
4
4
E
E
E E
E
E
E
E
E
E
E
E
3B
N
N
5N 5
3B
N
5N 5
5N 5N 5
3B
N
5
N
5
5
N
5N 5
N
5N 5
5
N
5
N
5
0
3B
5
N
5
5
6 6
6
6
6
6 6
6
6
6
0
5
0
5
6 6
0
5
6
6
6 6
6
6
6
9
9
7 7
9
7
7
7 7
7
9
7
7
7 7
7
7
7
7 7
7
7
7
8 8
15
8
8
8
8
8
15
8
8
8 8
15
8
8
8 8 8
15
8
8
8
1
1
0
5
1
1
9
1
1
051
1
9
1
1
0
5
1
1
9
1
1
051
1
2 2
9
2
2
10
2
2
9
2 2 10
POWER
2
2
9
2 2 10
2 2
9
2 2
O
O 3 O 3
O
3O 3
O 3O
3
11
O
3
O
3
15
O
3O 3 11
O
3
O
3
15
O
3O 3
11
O 3 3
15
P
P
P
P
P
15
P
P
P
P
P
P
P
4
P
4
4A
P
4
P
4 12
P
4
E
4
4A
E
4E 4
4 4
4A
E
4
E
4
12
4
E
4
4A
E
4E 4
12
E
E
E E E
5N5
N
N
5 N 5
N
5
N 5
13
N
5N5
N
5N5 13
N 5
N
5N5 13
N
0
N
E
E
E
5 5
N
5
5
6
7
8
5
9
15
4B
0
6
7
8
6
7
8 16
15
14
6
7
8
6 7 8
5
9
15
4B
0
6 7 8
6 7 8
16
15
146 7 8
6 7 8
5
9
15
4B
0
6 7 8
6
7 8
16
15
14
6
7 8
6 7 8
9
15
4B
6 7 8
6 7 8
6 7 8
POWER
SIGNAL PRESENT
1 2 3 4
5 6 7 8
O P E N
5
9
15
3A
5
9
15
3B
3A 3B
4A 4B
0
0
ATTENUATION LEVEL
1 2
3 4
5 6 7 8
O P E N
1 2 3 4
5 6 7 8
O P E N
1
2 3 4
5 6 7 8
O
P E
N
1 2
3
4 5 6 7 8
O P E N
O P E N
1 2
3 4
5 6 7 8
ATTENUATION LEVEL
1 2 3 4
5 6 7 8
5
9
15
3A
5
9
15
3B
0
0
O P E N
1
2 3 4
5 6 7 8
O P E N
1 2 3 4
5 6 7 8
1
2
3
4
5
6
7
8
O P E N
O P E N
1
2 3
4
5 6
7
8
ATTENUATION LEVEL
1
2
3
4
5 6
7
8
5
9
15
3A
5
9
15
3B
1
2 3 4
5
6
7 8
0
0
1
2
3
4
5 6 7 8
O P E N
1
2 3
4
5 6 7 8
O P E N
O
P E N
O P E N
1
2 3
4
5 6 7 8
ATTENUATION LEVEL
1
2
3
4
5 6 7 8
5
9
15
3A
5
9
15
3B
0
0
O P E N
1
2 3
4
5 6 7 8
O P E N
1 2
3
4
5 6 7 8
0
1
2
3
4
10
5
6
7
8
9
O P E N
O P E N
1 2 3 4
5 6 7 8
5
9
15
5
9
15
4A
4B
0
0
1 2 3 4
5 6 7 8
O P E N
O P E N
1
2 3 4
5 6 7 8
16
15
14
13
12
11
10
9
1 2 3 4
5 6 7 8
O P E N
O P E N
1 2 3 4
5 6 7 8
5
9
15
5
9
15
4A
4B
0
0
1 2 3 4
5 6 7 8
O P E N
O P E N
1
2 3 4
5 6 7 8
16
15
14
13
12
11
10
9
1 2 3 4
5 6 7 8
O P E N
O P E N
1
2 3
4 5
6
7
8
5
9
15
5
9
15
4A
4B
0
0
1 2
3
4 5
6
7
8
O P E N
O P E N
1
2
3 4
5 6
7
8
16
15
14
13
12
11
10
9
1 2 3 4
5 6
7
8
O P E N
O P E N
1
2
3 4
5 6
7
8
5
9
15
5
9
15
4A
4B
0
0
1 2 3 4
5 6
7
8
O P E N
O P E N
1
2
3 4
5 6 7 8
1 2 3 4
5 6 7 8
MAIN LEVEL
LOGIC CONT ROLLED A MPLIFIER.
LECTROSONICS, INC
These switches are used to programs which microphone (or microphones) connected to the 16 LOGIC INPUTS will trigger the "A" and "B" attenuation levels for each of the 16 output channels. Four banks of switches (eight switches per bank) are allocated to each channel. Two of the switch banks (16 switches) trigger the "A" attenuation level, the other two switch banks trigger the "B" attenuation level. The switch number is printed on the circuit board alongside the switch assemblies (disregard the numbers printed on the switch assembly itself).
ATTENUATION LEVEL CONTROLS (located between the DIP switch assemblies) These control the amount of "A" and "B" level attenuation for each output channel. "A" level attenuation always takes priority over "B" level attenuation and, therefore, the "A" control must always be set to a higher setting than the "B" control.
An enlarged view of the speaker #7 and #8 sections of the attenuation selection DIP switches and attenuation level controls is shown below. The attenuation select switches provide the means to select which microphones will attenuate each speaker and to what attenuation level. The output of each speaker amplifier may be attenuated from 0dB to completely off by means of the two continuously variable preset adjustment potentiometers ("A" and "B"). Therefore, each speaker may be attenuated by one or more microphones on either (or both) of the "A" or "B" levels as shown in the examples on page 7 and 8.
Figure 3 - Dip Switch Detail
4
CONTROLS AND FUNCTIONS - REAR PANEL
SPKR OUT
Connects to the individual speakers in the sound system. SPKR OUT (+) is the "hot" terminal, and SPKR OUT (-) is ground.
LINE OUT +/-
Provides balanced line level drive to external amplifiers or other equipment. The LINE OUT signal is attenuated identically to its associated speaker output. Output impedance is 600 ohms, and is suitable for driving both low and high impedance inputs.
LINE OUT
Provides the ground connection for the balanced line driver.
LOGIC INPUTS
Connects to the logic outputs of an automatic mixer, or to other types of contact closure. Logic Input (+) connects to the (+) terminal of logic output on an automatic mixer, and the Logic Input (-) is ground.
AUDIO INPUT
Receives the audio signal for the sound system. This input is electronically balanced and RF filtered, and uses a standard 3 pin XLR female connector.
AUDIO THRU
Outputs the signal received by the Audio Input for daisy chaining applications. This output is directly in parallel with the AUDIO INPUT.
FUSE
Protects the unit in case of internal overload. Replace only with a 1.5 amp slow blow fuse.
SER NO
LECTROSONICS, INC.
RIO RANCHO, NM - USA
WARNING
TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO
RAIN OR MOISTURE.
LISTED
COMMERCIAL AUDIO EQUIPMENT
R
4L01
US PATENT PENDING
CAUTION
TO REDUCE THE RISK OF FIRE,
REPLACE ONLY WITH SAME TYPE
1 1/2A, 250V "SLO-BLO" FUSE.
F
E
U
S
S
E
U
F
F
U
S
E
120V AC
200 WATTS
TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER. NO USER SERVICEABLE
PARTS INSIDE. REFER SERVICING TO.
QUALIFIED SERVICE PERSONNEL.
+
9
-
L
+
10
O
­G
+
11
I
­C
+
12
-
+
13
-
+
14
-
+
15
-
+
16
-
CAUTION
+
1
-
2
-
3
-
+
4
-
+
5
-
I
+
N
6
-
P U
+
7
T
-
S
AUDIO THRU
+
8
-
LECTROSONICS, INC.
AUDIO INPUT
MADE IN USA RI O RA NCHO , NM
13
14
15
16
AM 4
LCA16 OU TP UT MODU L E
SER NO
SPKR
SPKR
LINE OUT
LINE OUT
LINE OUT
SPKR
SPKR OUT
LINE OUT
LINE OUT
LINE OUT
SPKR
SPKR
LINE OUT
LINE OUT
LINE OUT
SPKR
SPKR
LINE OUT
LINE OUT
LINE OUT
SER NO
+
OUT
-
OUT
+
-
+
OUT
-
+
-
+
OUT
-
OUT
+
-
+
OUT
-
OUT
+
-
9
10
11
12
AM 4
LC A16 OUT P UT MODULE
SPKR OUT
SPKR OUT
LINE OUT
LINE OUT
LINE OUT
SPKR
SPKR
LINE OUT
LINE OUT
LINE OUT
SPKR OUT
SPKR
LINE OUT
LINE OUT
LINE OUT
SPKR
SPKR
LINE OUT
LINE OUT
+
-
5
+
-
+
OUT
-
OUT
+
-
OUT
+
-
+
OUT
-
OUT
+
-LINE OUT
+
-
6
7
8
AM 4
LCA16 OU TP UT MODU L E
SER NO
SPKR OUT
SPKR OUT
LINE OUT
LINE OUT
LINE OUT
SPKR OUT
SPKR
LINE OUT
LINE OUT
LINE OUT
SPKR OUT
SPKR OUT
LINE OUT
LINE OUT
LINE OUT
SPKR
SPKR OUT
LINE OUT
LINE OUT
LINE OUT
+
-
+
-
+
-
OUT
+
-
+
-
+
-
+
OUT
-
+
-
Figure 5 - LCA16 Rear Panel
SP KR OUT: O HMS
5W R M S @ 4 O H M S
3. 5 W R M S @ 8 O H M S
LI NE OUT: 60 0 OHM B ALANCED
AM 4
LCA16 OU TP U T MOD U L E
1
2
3
4
SER NO
CL A S S 2 WIRING
M A Y B E U S ED
OUT
SPKR
OUT
SPKR
LINE OUT
LINE OUT
OUT
SPKR
OUT
SPKR
LINE OUT
LINE OUT
SPKR OUT
SPKR OUT
LINE OUT
LINE OUT
LINE OUT
SPKR OUT
SPKR OUT
LINE OUT
LINE OUT
LINE OUT
+
-
+
-LINE OUT
+
-
+
-LINE OUT
+
-
+
-
+
-
+
-
5
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