Lectrosonics AM8, AM4 Operating Instructions And Owner's Manual

AM8/4

8 Channel Automatic Matrix Mixer

OPERATING INSTRUCTIONS

and trouble-shooting guide

LECTROSONICS, INC.

Rio Rancho, NM

www.lectrosonics.com

INTRODUCTION

The AM8/4 is the most advanced automatic matrix mixer available today. Combining 8 automatic
input channels, 2 auxiliary line inputs channels, 4 output channels, and a full crosspoint matrix
system into 1 rack space, the AM8/4 is a compact solution for a wide variety of sound system
applications. 8 nonvolatile preset memory positions mean complete flexibility and reconfigurability.

The 8 automatic inputs utilize Lectrosonics’ patented Proportional Gain plus Autoskew mixing
algorithm* for seamless automatic mixing performance. Input preamp gains include +50dB and
+30dB for both dynamic and electret microphones, and 0dB for line level inputs. Gain trim range on
the inputs is +15dB to -63dB plus off.

The crosspoint matrix allows any input (or combination of inputs) to be routed to any output (or
combination of outputs). Available crosspoints gains include -6dB, 0dB, +3dB, and off. In addition
to the 8 automatic inputs and 2 line inputs, audio from the LecNet Expansion connector can also be
routed to any or all of the 4 outputs.

The AM8/4 features a wealth of programmable features. With 13 programmable inputs and 8
programmable outputs, even the most sophisticated control schemes are straightforward. The
programmable inputs can control input or output level on any grouping of inputs or outputs, memory
preset recall, or matrix crosspoint switching. Programmable outputs can indicate the current state of
a programmable input.

The AM8/4 has an RS-232 port for remote setup or control by a computer or other RS-232 compat­ible controller. More than one AM8/4 may be coupled together for larger applications.

TABLE OF CONTENTS

INTRODUCTION ................................................................................................... 2

GENERAL TECHNICAL DESCRIPTION ............................................................. 3

INSTALLATION ...................................................................................................... 4

FRONT PANEL DESCRIPTION ............................................................................ 6

REAR PANEL DESCRIPTION .............................................................................. 7

OPERATING INSTRUCTIONS ............................................................................. 8

AM8/4 CONTROL PANEL SOFTWARE ............................................................. 10

TROUBLESHOOTING......................................................................................... 19

FCC PART 15 NOTICE ....................................................................................... 19

SERIAL CABLE WIRING DIAGRAM................................................................. 20

AMX CABLE WIRING DIAGRAM ....................................................................... 20

SERIAL PORT COMMANDS AVAILABLE ......................................................... 21

SPECIFICATIONS ............................................................................................... 26

SERVICE AND REPAIR ...................................................................................... 27

RETURNING UNITS FOR REPAIR .................................................................... 27

WARRANTY ........................................................................................... Back cover

U.S. Patents 5,402,500 and 5,414,776

2

8 Channel Automatic Matrix Mixer

GENERAL TECHNICAL DESCRIPTION

The AM8/4 uses a straightforward analog signal path to provide excellent audio performance. This is coupled with a
sophisticated microcontroller to implement the automatic mixing, matrix control, and programmable input and output
functions. The Adaptive Level Proportional automatic mixing algorithm is used by the AM8/4. This algorithm uses
the signal level pattern at the microphones to derive a pattern of channel gains. For instance, if only one microphone
channel is being spoken into, its level is dominant and that channel gets most of the system gain, while all other
channels are turned down. If more than one microphone is active, they share system gain according to their relative
levels. A “skewing” function gives some advantage to microphones which are active over time, to minimize interrup­tions from transient noise at other microphones. Since the gain of each channel is apportioned continuously based
on its relative level, no abrupt gain changes are made. This makes the automatic action virtually inaudible.

Figure 1 shows the simplified block diagram of the AM8/4. The microphone preamp is a low-noise discrete design,
which is extensively RF protected. The preamp has three gain settings. The 0dB setting allows an input to accept
line level signals, while the +30dB and +50dB gain settings accommodate both low and high sensitivity microphones.
Switchable 15V Phantom power is provided for each channel.

Following the mic preamp, the audio signal passes through a high quality Voltage Controlled Amplifier (VCA). This
VCA, controlled by a signal from the system D/A converter, is used to implement both static gain control (i.e. mic trim
and remote input level) and gain reduction for the automatic mixing function. A Channel On LED indicates which
inputs are currently active. A sweepable low-cut filter and a shelving high frequency filter provide tone control for
each input.

The 8 automatic inputs and 2 line inputs are routed through an 11 in / 4 out crosspoint matrix. The matrix has
multiple crosspoint gains to accommodate the most complex signal routing needs. Aside from the 10 inputs, the
matrix also includes one other inputs: the LecNet Expansion In rear panel connector.

Signals from the Expansion In and Expansion Out connectors allow easy interface to AM8 mixers. In addition, a Mix
Minus signal is available which allows easy interfacing to teleconferencing hybrids like the TH3.

An RS-232 port is available to allow many of the functions of the AM8/4 to be controlled either by a computer or a
dedicated control system (such as the AMX or Crestron systems).

MAIN IN

MIX MINUS OUT

AUTO MIX LOG IN

MAIN OUT

MIX MINUS IN

AUTO MIX
LOG OUT

TX

RX

15dB

15dB

EXPANSION

IN

EXPANSION

OUT

LECNET

PORT

(RS-232)

AUDIO
LINK IN

AUDIO
LINK OUT

BALANCED
LINE OUTPUT 1

BALANCED
LINE OUTPUT 2

BALANCED
LINE OUTPUT 3

BALANCED
LINE OUTPUT 4

AM8/4

Block

Diagram

DIR OUT

+15V

MIC IN +

MIC IN -

MIC GND

PROGRAMMABLE I/O
PROGRAMMABLE I/O
PROGRAMMABLE I/O
PROGRAMMABLE I/O
PROGRAMMABLE I/O
PROGRAMMABLE I/O
PROGRAMMABLE I/O
PROGRAMMABLE I/O
PROGRAMMABLE INPUT
PROGRAMMABLE INPUT
PROGRAMMABLE INPUT
PROGRAMMABLE INPUT
PROGRAMMABLE INPUT

LINE IN +
LINE IN -

PHANTOM
POWER

PREAMP GAIN

LINE INPUT (1 OF 2)

VARIABLE LOW CUT

HIGH CUT/BOOST

+

MIC
PREAMP

-

0dB (LINE)
+30dB (MIC)
+50dB (MIC)

AUTO INPUT (1 OF 8)

CHANNEL ON

FROM D/A
CONVERTER

LOG

CONVERTER

VARIABLE LOW CUT

HIGH CUT/BOOST

TO
A/D CONVERTER

1 OF 8

PROCESSOR

CONTROLLED

VARIABLE
RESISTOR

AUDIO

VCA

SPEECH

FILTER

1
2
3
4
5
6
7
8
9
10
11
12
13

1 OF 2

PROCESSOR
CONTROLLED

VARIABLE

INPUT
LEVEL

RESISTOR

FROM INPUT
FROM INPUT
FROM INPUT
FROM INPUT
FROM INPUT
FROM INPUT

FROM INPUT
FROM LINE INPUT
FROM LINE INPUT

MIX BUS 3

MIX BUS 2

MIX BUS 4

MIX BUS 1

PROCESSOR

CONTROLLED

2
3
4
5
6
7
8
1
2

PROCESSOR

CONTROLLED

VARIABLE
RESISTOR

SWITCH

ARRAY

uC

68HC12

SERIAL
BUS

PROCESSOR
CONTROLLED
ATTENUATORS

15dB

15dB

Rio Rancho, NM – USA

3

INSTALLATION

s

The AM8/4, because it is so highly integrated, is straightforward to install. The following sections explain the installa­tion and wiring, as well as the software setup of the AM8/4.

AM8/4 Audio Inputs

Each of the 8 automatic AM8/4 inputs is balanced, and
provides 15V phantom power (through 2K ohm feed
resistors to the “+” and “-” input connections). Phantom
power is switchable on a per-channel basis. The drawing
to the right shows two examples of line level interface

Unbalanced Line Level Source

Input +
Input ­Gnd

Balanced Line Level Source

Input +
Input ­Gnd

with the AM8/4; one, an unbalanced line level source and
the other, a balanced line level source. The 2 line inputs are balanced but without switchable Phantom power.

AM8/4 Audio Outputs

Each of the 4 AM8/4 outputs is balanced. To use an output in the unbalanced mode, take the signal from the “+”
output connection and the output ground. Leave the “-” output floating.

AM8/4 Programmable Inputs

The AM8/4 has 13 programmable inputs which can control a variety of AM8/4 parameters. Each input can respond
to either a contact closure or a continuous voltage. The diagram to the right shows common connections to the
programmable input pins.

Pot Connection for Analog Control of Gain

10K Linear Pot

CCW

CW

+5V

1k Ohm

Gnd

To Programmable Input Pin - 1k series resistor recommended

Contact Closure as Programmable Input

To Programmable Input Pin

Gnd

DC Voltage Source as Programmable Input

To Programmable Input Pin

0VDC (Off) to +5VDC (On)

Gnd

Each programmable input is internally pulled up through a 100K resistor to +5V, so no external pull up resistors are
necessary. When using a continuous voltage with one of the programmable inputs, the Function of the program­mable input must be set to either Analog In Control or Analog Out Control. See the Programmable Input tab in the
AM8/4 Control Panel software for setting all programmable input parameters.

AM8/4 Programmable Outputs

The AM8/4 has 8 programmable outputs which can indicate the current state of a programmable input. Each pro­grammable output is the electrical equivalent of a contact closure to ground. When a programmable output is
“active”, it conducts current to ground. When the programmable output is “inactive”, no current flows to ground. The
maximum usable voltage for the programmable outputs is 40V, and they will safely conduct up to 100mADC continu­ous. The diagram on the right shows some typical uses for the programmable outputs.

It is permissible to run LEDs
from the +5VDC pins on the
programmable input connector,
as long as the total LED current
for all LEDS on does not
exceed 100mA. Similarly, 5V

LED is on when the programmable output is active

+5VDC (from Pin 14)

380
Ohms

Programmable Output Pin

LED is off when programmable output is active

+5VDC (from Pin 14)

380
Ohm

Programmable Output Pin

relay coils may also be run
from the +5VDC pins on the

GND (from Pin 15)

programmable input connector,
as long as the total coil current

Relay is on when programmable output is active

for all relays on does not
exceed 50mA. Note that the
diagram shows an external DC
source powering the relay coil.
This will be necessary if coil
voltages above 5V are needed.

4

Coil current < 100mA

Programmable Output Pin

GND (from Pin 15)

Relay Coil

1N4001
or equiv.

External DC Voltage
Source (<40VDC)

8 Channel Automatic Matrix Mixer

"

"

Audio Expansion In/Out

When multiple AM8/4s are used in an application, their Audio Link ports must be interconnected using the Audio Link
In/Out connectors on the rear panel of the AM8/4. The Audio Link In/Out connector is just to the right of the Program­mable In/Out connector on the rear panel. An 8 pin mini-DIN cable is supplied with each AM8/4 for this purpose.
When installing the AM8/4s in a rack, the Master AM8/4 should be mounted in the top of the rack, with Slave AM8/4s
mounted below the Master AM8/4. The 8 pin mini-DIN cable then connects the Audio Link In connector of the Master
AM8/4 to the Audio Link Out connector of the first Slave AM8/4. If there is more than one Slave AM8/4, the Audio
Link In connector of the first Slave AM8/4 is connected to the Audio Link Out connector of the second Slave AM8/4,
and so on for as many Slave AM8/4s as exist in the system.

Switch in

MASTER"

position

Switch in

"SLAVE"

position

Switch in

"SLAVE"

position

M
A

S

S

L

T

A

E

V

R

E

EXPANSION

O
U
T

I
N

AUDIO LINK

O
U
T

I
N

Switch in

MASTER"

position

M
A
S
T
E
R

EXPANSION

S
L
A
V
E

O
U
T

I
N

AM8/4 Rear Panel

AUDIO LINK

AUDIO LINK

O
U
T

I
N

Switch in "EXPAN" position

O
U
T

I
N

L

E

O

X
P

C

A

A

N

L

EXPANSION

IN

OUT

TH3 Rear Panel

M
A

S

S

L

T

A

E

V

R

E

M
A

S

S

L

T

A

E

V

R

E

EXPANSION

EXPANSION

O
U
T

I
N

O
U
T

I
N

To additional AM8/4s

Connecting multiple AM8/4s together Connecting the AM8/4 to the TH3

AUDIO LINK

O
U
T

I
N

EXPANSION

O
U
T

M

I

A

S

N

S

L

T

A

E

V

R

Switch in

"MASTER"

position

E

M
A
S
T
E
R

EXPANSION

S
L
A
V
E

AM8/4 Rear Panel

IN

OUT

Switch in "SLAVE" position

Connecting the AM8/4 to the AM8

AUDIO LINK

O
U
T

I

N

AM8 Rear Panel

Switch in

"MASTER"

position

Switch in "EXPAN"
position

Connecting the AM8/4 to the TH3 and a video codec

Rio Rancho, NM – USA

E

L

X

O

P

C

A

A

N

L

EXPANSION

OUT

EXPANSION

O
U

M
A
S
T
E
R

IN

T

I

S

N

L
A
V
E

TH3 Rear Panel

AUDIO LINK

AM8/4 Rear Panel

CODEC

OUTIN

Video

Codec

O
U
T

I
N

5

When other LecNet devices are used in conjunction with the AM8/4s, the LecNet Expansion ports of these devices

o

o

must also be interconnected. Refer to the diagrams above for proper interconnections. The LecNet Expansion In
and Out pinouts are shown below.

Pin Expansion In Function Expansion Out Function

1 Main In Main Out
2 Mix Minus Out Mix Minus In
3 NOM In NOM Out
4 NOM Total NOM Total
5 RS-232 RX RS-232 RX
6 RS-232 TX RS-232 TX
7 Ground Ground
8N/C N/C

Pin Link In Function Link Out Function

1 In 1 Out 1
2 In 2 Out 2
3 In 3 Out 3
4 In 4 Out 4
5Gnd Gnd
6N/C N/C
7N/C N/C
8N/C N/C

6

7

8

5

2

7

8

5

2

LecNet

3

4

Expansion
Out

1

6

LecNet

3

4

Expansion
In

1

LecNet Expansion In/Out

6

7

8

5

2

7

8

5

2

Audi

3

4

Link
Out

1

6

Audi

3

4

Link
In

1

Audio Link In/Out

FRONT PANEL DESCRIPTION

LECTROSONICS, INC.

CHANNEL ACTIVITY SECTION

CHANNEL ACTIVITY LEDS - Indicates channel activity. The LEDs light when the attenuation applied by the auto-

matic mixing algorithm is less than or equal to 6dB.

RESET DEFAULTS – When pressed during power-up, resets the preset memories to their factory defaults. Note that
this will overwrite any user information which may have been stored in the preset memories. There are two reset
modes. If the Reset Defaults button is held in during the first blink of the Power LED after turn-on and then released,
only the preset memories will be set to factory defaults. If the button is held through two blinks of the Power LED, the
LecNet address will be reset to 145 and the preset memories will be set to factory defaults.

6

AM8/4 Front Panel

AUTOMATIC MATRIX MIXER

3

1

456

2

CHANNEL ACTIVITY

8

7

RESET

DEFAULTS

POWER

8 Channel Automatic Matrix Mixer

REAR PANEL DESCRIPTION

6 - Prog I/O 6

PWR

(PS60)

16.5 VAC
20VA

EXPANSION

IN

M
A

S

S

L

T

A

E

V

R

E

1 - Prog I/O 1
2 - Prog I/O 2

O

3 - Prog I/O 3

U

4 - Prog I/O 4

T

5 - Prog I/O 5

PROGRAMMABLE IN / OUT

I
N

LecNet

(RS232)

MIC/LINE INPUTS 1-8 - Accepts balanced or unbalanced signal. Fully balanced differential input, RF filtered.

DIR OUT - Provides a line level signal from each individual channel. The direct output is a post-VCA signal. Any attenua-

tion from the auto mixing process, compressor/leveler system or remote attenuation will be reflected in the direct out signal.
This provides versatility for different mixing applications such as distributed overhead speaker systems. This 100 Ohm
output provides a +20dBu max signal into a high impedance load.

When connecting to other equipment, the ground connection of the OUTPUTS will also be adequate for

all the direct outputs. A separate ground connection is not needed for each direct out.

GAIN SELECTION SWITCHES 1-8 - Allows input channel gain to be set. 0dB gain, for line level sources, is set when both
switches of the pair are in the up position. 30dB gain, typically for high output (electret) microphones, is set when the left
switch is in the up position and the right switch is in the down position. 50dB gain, used for low output (dynamic) micro­phones, is set when both switches are in the down position.

11 - Prog IN 11
12 - Prog IN 12
13 - Prog IN 13
14 - +5V
15 - GND

AUDIO LINK

O
U
T

I
N

OUTPUTS LINE IN

4321

+––+ +––+

21

+––+

PHANTOM PWR

CH1 - CH8

OFF

ON

CH8 IN

DIR
OUT

12345678

CH7 IN

DIR

+

–

DIR

+

–

OUT

OUT

7 - Prog I/O 7
8 - Prog I/O 8
9 - Prog IN 9
10 - Prog IN 10

AM8/4 Rear Panel

Note: The DIR OUT shares a ground with the OUTPUTS.

--Don’t use the CHANNEL IN grounds for the DIR OUT!--

CH6 IN

–

0dB GAIN

+30dB GAIN

(LINE)

(ELECTRET)

CH5 IN

DIR

+

+

–

OUT

DIR
OUT

CH4 IN

–

+50dB GAIN

(DYNAMIC)

CH2 IN

CH3 IN

DIR

DIR

+

+

–

OUT

OUT

CH1 IN

DIR

+

–

+

–

OUT

LINE INPUTS 1-2 – Accepts line level balanced or unbalanced axillary inputs. The line inputs do not participate in the
automatic mixing algorithm.

LINE OUTPUTS 1-4 - Provide balanced system outputs. The Line Outputs may also be used in an unbalanced mode by
connecting the “+” terminal of the Line Output to the signal lead of the unbalanced device, and the ground terminal of the
Line Output to the ground of the unbalanced device. Do not connect the “-” terminal of the Line Output.

AUDIO LINK IN/OUT - Provides a means to link the four output buses of multiple AM8/4s. All inputs from all linked AM8/4s
will be available at the outputs of the master AM8/4.

PROGRAMMABLE INPUTS/OUTPUTS - Allows remote control of a number of AM8/4 functions. Pins 1-8 on the 15 pin D­Sub connector may be programmed to be either programmable inputs or programmable outputs. Pins 9-13 are program­mable inputs only.

Each of the 13 programmable inputs can utilize either continuous DC voltages (0VDC-5VDC) or contact closures, depend­ing on the particular function chosen. For continuous voltages, either 10K ohm linear pot or an adjustable DC control
voltage may be used. The volume control action is internally audio scaled in software. This gives an “audio-taper” charac­teristic to a linear pot. When using a DC control voltage, the control constant is .167V/dB (or 6dB/V) from 0V to 5V. At 0V,
the channel is turned completely off. The control voltage should not exceed 5V.

Programmable outputs allow indication of programmable input states. Each of the 8 programmable inputs is the electronic
equivalent of a contact closure. The logic output will sink up to 100mA at voltages up to 40VDC, however, the total current
draw of all logic outputs should not exceed 50mA if the internal +5V supply is used.

AUDIO EXPANSION IN/OUT - Allows multiple AM8/4s to be linked together when more than 8 inputs are needed. In
multiple AM8/4 setups, one AM8/4 is set to be the Master, and all others are set to be Slaves. The Audio Expansion In of
the Master AM8/4 is connected to the Audio Expansion Out of the first Slave AM8/4, using the supplied LecNet Expansion
cable. The Audio Expansion In of the first Slave AM8/4 is connected to the Audio Expansion Out of the next Slave AM8/4,
and so on.

RS-232 SERIAL PORT - Provides access to and control of some of the operational features of the AM8/4. The port is
compatible with the serial port of a PC, or other controllers with RS-232 type serial ports. For hardware interconnection
and software details, see Appendix 1, “Serial Port Hardware and Software”.

EXPANSION IN/OUT - Allows other LecNet devices to be connected to the AM8/4. Also used when multiple AM8/4s are
connected together to bus the RS-232 serial connection between AM8/4s.

MASTER/SLAVE SWITCH - Sets the AM8/4 for use as a Master device or a Slave device. AM8/4s used singly should be
set for Master mode operation.

PWR IN - Connects to the PS60 power supply to provide power for the AM8/4.

PHANTOM POWER SWITCHES - Allow +15V phantom power to be applied or not on a per-channel basis.

Rio Rancho, NM – USA

7

OPERATING INSTRUCTIONS

r

Since most of the parameters used to set up the AM8/4 are adjusted using the AM8/4 Software Control Panel, the
operating instructions include instructions for the use of the software. It’s recommended that you have the software
running, either live or in the demo mode, as you read through this section.

Power Up

When the AM8/4 is powered on, it automatically loads the active setup from Preset 1. Therefore, you should always
store the desired power-up setting for the AM8/4 in Preset 1.

Master/Slave Switch

The Master/Slave switch should be set to the Master position if only one AM8/4 is being used. When multiple AM8/
4s are used in a system, only one is set to Master and the rest are set to Slave. See also the wiring descriptions of
the Audio Expansion In/Out and Expansion In/Out connectors in the Installation section.

Input Preamp Gain

Input preamp gain is set using the dip switches just to the left of each 5 pin input connector. Dip switch settings for
0dB, +30dB, and +50dB input gain are shown on the rear panel of the AM8/4. Generally, the +50dB position is used
for all dynamic microphones and electret microphones where the working distance from the microphone will be
greater than about 18 inches. The +30dB position is useful for electret microphones with working distances less than
18 inches and most wireless microphones. The 0dB setting is for line level sources. Remember to switch phantom
power on for electret microphones and off for dynamic mics or line level sources.

Using the AM8/4 PC Hosted Control Panel

The AM8/4 control panel may be used in one of two ways. When launched from the LecNet Master Pro application,
you can control all the parameters of the AM8/4 in real time. Needless to say, your PC must be connected to the
AM8/4 using the supplied LecNet serial cable in order for this to happen. Alternatively, you can launch the AM8/4
control panel directly and it will automatically come up in the demo mode. The demo mode is useful for doing system
setup (and saving the setups to a disk file) without the need to be connected to an AM8/4.

System setup follows the order of the tabs on the control panel. Star t at the left tab and work your way to the right.
Please refer to the AM8/4 Control Panel Software section of this manual for a complete description of each control
panel tab.

The diagram below represents the signal flow of one input to one output through one matrix crosspoint. Illustrated
are all the gain control points in the signal path.

+50dB, +30dB, 0dB

Mic/Line In

Input Channel (1 of 16)

Mic Preamp

Input Gain

+15dB to -63dB, Off

Front Panel

+9dB, to -9dB, Off

Rear Panel

0dB to -30dB, Off

Tone Controls

Matrix Crosspoint

(1 of 216)

+6dB

+3dB

0dB

-5dB

-10dB

-15dB
+10dB to -68dB, Off

Output Channel (1 of 12)

Front Panel

+9dB to -9dB, Off

Output Gain

0dB to -30dB, Off

To Balanced
Output Drive

Rear Panel

To adjust this parameter: Use this control:

Mic Preamp Gain Rear panel dip switches
Input Gain Input gain tab on AM8/4 control panel software
Rear Panel (Input) Gain Programmable inputs on AM8/4 rear panel
Output Gain Output gain tab on AM8/4 control panel software
Rear Panel (Output) Gain Programmable inputs on AM8/4 rear panel

Each input channel has two gain control points, in addition to the rear panel preamp gain switches. The input control
point labeled “Input Trim” is adjusted using the Input Gain tab on the AM8/4 control panel. This control is used to
adjust the sensitivity of each microphone or line level input to the desired gain. The gain adjustment range is +15dB
to -63dB plus off. You may want to increase the mic preamp gain if you find that your input gain settings are routinely
above +10dB.

8

8 Channel Automatic Matrix Mixer

The input control point labeled “Rear Panel” represents the gain adjustments which can be made from the rear panel
programmable inputs. The rear panel gain control is attenuation only, starting at a maximum gain of 0dB. The rear
panel input gain controls may be limited in their adjustment range using the Remote Input/Output Level Limits tab on
the AM8/4 control panel. In addition, you may set a rear panel preset gain value that will be applied to any outputs
which are being controlled by a programmable input. The preset gain is applied at power up. Note that if there are
no limits applied to the rear panel gain range, the input channel may be turned completely off. The current gain value
of the rear panel controls is displayed on the Remote Input/Output Level Limits tab.

The output gain structure is identical to the input gain structure. The Output Gain range adjustment is +15dB to ­63dB plus off. The output gain is adjusted using the Output Gain tab. Rear panel output gain control ranges may be
set in a similar fashion to the input control ranges in the Remote Input/Output Level Limits tab.

Matrix crosspoint gain can be set using the Matrix tab. Input-to-output gains are set based on the requirements of
the application. For example, you can set up a “mix-minus” sound reinforcement system when you are using multiple
microphones and overhead distributed speakers. Each speaker (or small group of speakers) would be fed from its
own mix of microphones. A given speaker’s mix would consist of all microphones not physically close to the speaker,
while excluding those microphones which are close to the speaker. The possibility of feedback is greatly reduced
when this approach is repeated with all system speakers. A multichannel amplifier (like the Lectrosonics PA8) may
be used to power each speaker individually.

Programmable inputs and outputs may be set up using the Programmable Input/Output tab. Below is a short list of
typical applications for each of the programmable input functions available:

Analog In Control: Used to control the input gain of one or more inputs with a potentiometer or DC
voltage source. Additionally, a toggle switch can be used as a mute switch by shorting the program­mable input to ground for mute.

Increase In 1dB, Decrease In 1dB: Used to control the input gain of one or more inputs with
momentary switch closures. Each switch closure will increase or decrease the gain of the associ­ated input(s) by 1dB. If the switch is pushed and held, it will continue to increment or decrement until
the switch is released or the gain reaches its high or low limit.

Analog Out Control: Used to control the output gain of one or more outputs with a potentiometer or
DC voltage source. Additionally, a toggle switch can be used as a mute switch by shor ting the
programmable input to ground for mute.

Increase Out 1dB, Decrease Out 1dB: Used to control the output gain of one or more inputs with
momentary switch closures. Each switch closure will increase or decrease the gain of the associ­ated input(s) by 1dB. If the switch is pushed and held, it will continue to increment or decrement until
the switch is released or the gain reaches its high or low limit.

Memory Preset: Used to recall one of the 15 AM8/4 preset memories with a momentary switch
closure. Remember to save the same memory preset associations in all the AM8/4 memory preset
positions you’ll be using. You can also assign a programmable output to reflect the programmable
input state of the programmable inputs you’re using for memory preset recall to drive LEDs for visual
feedback of the current memory preset.

Toggle Crosspoint Gain: Used to temporarily apply the signal from any one of the 16 inputs to any
combination of outputs using a momentary switch closure to toggle the state of the affected
crosspoints. Useful for zone paging applications, etc.

Mute In: Used to mute one or more inputs with a switch closure. Subsequent contact closures
toggle between mute and unmute. You can also assign a programmable output to reflect the pro­grammable input state of the programmable inputs you’re using for input muting to drive LEDs for
visual feedback of the mute/unmute state of the inputs.

Mute Out: Used to mute one or more outputs with a switch closure. Subsequent contact closures
toggle between mute and unmute. You can also assign a programmable output to reflect the pro­grammable input state of the programmable inputs you’re using for output muting to drive LEDs for
visual feedback of the mute/unmute state of the outputs.

Rio Rancho, NM – USA

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