AUDAC COM108 User manual

COM104/108
User Manual
www.audac.eu

2
ADDITIONAL INFORMATION
This manual is put together with much care, and is as complete as could be on the
publication date. However, updates on the specifications or functionality may have occurred
since publication. To obtain the latest instruction manual or obtain additional product
information, please visit the product page on www.audac.eu.

3
Index
Introduction 5
Precautions 6
Safety requirements 6
Caution servicing 7
EC Declaration of Conformity 7
Waste of Electrical and Electronic Equipment (WEEE) 7
Caution 7
Chapter 1: Pin connections and connectors 8
Connection standards 8
Chapter 2: Front & rear panel 9
Front panel overview 9
Front panel description 9
Rear panel overview 10
Rear panel description 10
Chapter 3: Setting up the system 11
Chapter 4: Additional information 14
Technical specifications 14
Notes 15

4

5
Introduction
Public address mixing amplifier
The COM104/108 are compact but versatile public address mixing amplifiers, offering solutions
for small to medium size audio systems in commercial installations. Typical applications are
background music systems in retail stores, bars, restaurants and office buildings.
The compact and simple design allows installation in any location and operation through
any possible user.
The amplifiers are designed using Class-D amplifier technology and delivers an output power
up to 80 Watt (40 Watt for COM104) to constant voltage (100V and 70V) or low impedance (4
Ohm) audio systems. A switch mode power supply allows compatibility with a wide variation
of mains voltages for global compatibility.
A stereo line input allows connection for a wide variation of audio sources such as media
players, radio tuners, internet audio players, ... and many more. A balanced mic / line
input allows connection for an announcement microphone with compatibility for condenser
microphones using the integrated phantom power supply (15V). A priority switch overrides
the background music when enabled, and compatibility with voice file players is guaranteed
by the wide gain adjustment possibility (0 dB - +50 dB).
Desktop installation or mounting in an equipment rack using (optionally available) mounting
adapters is possible. The half 19” rackspace enclosure allows single installation in a 10.5”
equipment rack, or side-by-side (two devices) in a 19” equipment rack.

6
Precautions
READ FOLLOWING INSTRUCTIONS FOR YOUR OWN SAFETY
ALWAYS KEEP THESE INSTRUCTIONS. NEVER THROW THEM AWAY
ALWAYS HANDLE THIS UNIT WITH CARE
HEED ALL WARNINGS
FOLLOW ALL INSTRUCTIONS
NEVER EXPOSE THIS EQUIPMENT TO RAIN, MOISTURE, ANY DRIPPING OR SPLASHING
LIQUID. AND NEVER PLACE AN OBJECT FILLED WITH LIQUID ON TOP OF THIS DEVICE
NO NAKED FLAME SOURCES, SUCH AS LIGHTED CANDLES, SHOULD BE PLACED ON
THE APPARATUS
DO NOT PLACE THIS UNIT IN AN ENCLOSED ENVIRONMENT SUCH AS A BOOKSHELF
OR CLOSET. ENSURE THERE IS ADEQUATE VENTILATION TO COOL THE UNIT. DO NOT
BLOCK THE VENTILATION OPENINGS.
DO NOT STICK ANY OBJECTS THROUGH THE VENTILATION OPENINGS.
DO NOT INSTALL THIS UNIT NEAR ANY HEAT SOURCES SUCH AS RADIATORS OR
OTHER APPARATUS THAT PRODUCE HEAT
DO NOT PLACE THIS UNIT IN ENVIRONMENTS WHICH CONTAIN HIGH LEVELS OF DUST,
HEAT, MOISTURE OR VIBRATION
THIS UNIT IS DEVELOPED FOR INDOOR USE ONLY. DO NOT USE IT OUTDOORS
PLACE THE UNIT ON A STABLE BASE OR MOUNT IT IN A STABLE RACK
ONLY USE ATTACHMENTS & ACCESSORIES SPECIFIED BY THE MANUFACTURER
UNPLUG THIS APPARATUS DURING LIGHTNING STORMS OR WHEN UNUSED FOR LONG
PERIODS OF TIME
ONLY CONNECT THIS UNIT TO A MAINS SOCKET OUTLET WITH PROTECTIVE
EARTHING CONNECTION
THE MAINS PLUG OR APPLIANCE COUPLER IS USED AS THE DISCONNECT DEVICE, SO
THE DISCONNECT DEVICE SHALL BE READILY OPERABLE
USE THE APPARATUS ONLY IN MODERATE CLIMATES

7
EC DECLARATION OF CONFORMITY
This product conforms to all the essential requirements and further
relevant specifications described in following directives: 2014/30/EU
(EMC) and 2014/35/EU (LVD)
CAUTION - SERVICING
This product contains no user serviceable parts. Refer all servicing to
qualified service personnel. Do not perform any servicing (unless you
are qualified to)
CAUTION
The symbols shown are internationally recognized symbols that warn about potentional
hazards of electrical products. The lightning flash with arrowpoint in an equilateral
triangle means that the unit contains dangerous voltages. The exclamation point in
an equilateral triangle indicates that it is necessary for the user to refer to the users
manual.
These symbols warn that there are no user serviceable parts inside the unit. Do not
open the unit. Do not attempt to service the unit yourself. Refer all servicing to qualified
personnel. Opening the chassis for any reason will void the manufacturer’s warranty. Do
not get the unit wet. If liquid is spilled on the unit, shut it off immediately and take it to a
dealer for service. Disconnect the unit during storms to prevent damage.
WASTE ELECTRICAL AND ELECTRONIC EQUIPMENT (WEEE)
The WEEE marking indicates that this product should not be disposed
with regular household waste at the end of its life cycle. This regulation
is created to prevent any possible harm to the environment or human
health.
This product is developed and manufactured with high quality materials
and components which can be recycled and/or reused. Please
dispose this product at your local collection point or recycling centre
for electrical and electronic waste. This will make sure that it will be
recycled on an environmentally friendly manner, and will help to protect
the environment in which we all live.

8
Chapter 1
Pin connections and connectors
CONNECTION STANDARDS
The in- and output connections for AUDAC audio equipment are performed corresponding
to international wiring standards for professional audio equipment.
Cinch (RCA):
For unbalanced line input connections
Tip: Signal Sleeve: Ground
3-Pin Terminal block:
For balanced signal input connections
Left: Signal - (XLR Pin 3)
Center: Signal + (XLR Pin 2)
Right: Ground (XLR Pin 1)
For balanced signal input connections
:
For unbalanced signal input connections

9
Chapter 2
Front & rear panel
Front panel overview
Front panel description
3.5 mm Jack input:
A 3.5 mm jack connection is located on the left side of the front panel. This easy accessible
input is an unbalanced stereo line input whereto any portable audio device (such as laptop,
smartphone or tablet) with 3.5 mm jack audio output can be connected. It is combined with
the line input on the rear amplifier side (connected by RCA connectors), meaning the rear
side input is disabled when the front 3.5 mm jack is connected.
Input mixing controls:
Using the input mixing controls, the level for each individual input (Line in or Mic in) can be
adjusted.
Output master control:
The output section contains a master volume control, two band tone control and indicator
LED’s. The master volume control allows regulation of the overall output level, while two-band
tone control allows bass / treble adjustment within a range of ± 12 dB and the indicator LED’s
indicate the overall output level and status of the amplifier (Signal / -20 dB / Clip / Protect).
Power switch:
Allows to power the system ON and OFF. The blue indicator LED illuminates when switched on.
Compact half 19” rackspace enclosure:
The amplifiers are housed in a compact half 19” rackspace enclosure which can be used for
desktop installation or mounted in an equipment rack using (optionally available) mounting
adapters. The half 19” rackspace enclosure allows single installation in a 10.5” equipment
rack, or side-by-side (two devices) in a 19” equipment rack.

10
Rear panel overview
Rear panel description
AC Power inlet with fuse:
The mains power supply (100-240V AC - 50/60 Hz) has to be applied to this AC power inlet.
The connection is made by an IEC C14 power connector.
Priority mute contact:
A priority mute contact mutes the music at presence of a contact closure between both
terminals. When priority on the microphone input (Mic in) is enabled, the applied signal will
override the muting which allows emergency announcements or voice messages. This contact
is convenient for situations where a separate emergency system is installed and complete
background music muting is required at occasion of a (fire) alarm. The emergency system
contact outputs can be connected to this contact input.
Loudspeaker output connections:
Output connections for both low impedance (4Ω) and constant voltage distributed audio
systems are provided. These outputs are connected using a 4-pin terminal block connection,
with various connection terminals for different output voltage / impedance. More information
about loudspeaker output connections is described in a further chapter of this instruction
manual.
Unbalanced stereo line input:
An unbalanced line level input source (e.g. media-players, radio tuners, ...) can be connected
to the line input which is implemented through RCA connectors. It is fitted with a gain control
potentiometer whereby the input sensitivity can be controlled within a range of +4 dB ~
-20 dB.
NOTE
The gain control potentiometers for the RCA unbalanced stereo line input (rear) also affects
the level for the 3.5 mm jack input connection (front). When switching between front and
rear input, it is recommended to configure both connected audio sources with equal output
levels to allow easy switching (without adjusting the rear input gain).
Balanced microphone input:
Balanced mono sources can be connected to the microphone input which is implemented
using a terminal block connector. It is fitted with a gain control potentiometer whereby the
sensitivity can be adjusted within a range of 0 dB ~ -50 dB which allows connection for
both microphone or line level audio sources (e.g. voice file announcement systems).
A phantom power switch enables 15 Volts phantom power supply for powering condenser
microphones and a priority switch eleminates other connected audio sources once a signal
is present on this input. When priority enabled, this inputs also overrides the priority mute.

11
Chapter 3
Setting up the system
ATTENTION
Make sure the power of the device is turned OFF before any connections or wiring
adjustments are made. Disregarding this rule can lead to permanent damage of the
equipment.
1) Connecting the loudspeakers
The loudspeakers should be connected to the 4-pin terminal block connector on the rear
panel of the amplifier. Selection can be made between low impedance (4Ω) or constant
voltage (100V / 70V) depending on project requirements. The corresponding terminals shall
be connected depending of the loudspeakers and installation type. It is only allowed to use
one (either constant voltage or low impedance) of both options at a time.
The table below shows the output voltage, impedance and maximum power load for each
amplifier model.
COM104
COM108
4 Ω/ 12.65 V
4 Ω/ 17.89 V
125Ω/ 70 V
62.5Ω/ 70 V
250Ω/ 100 V
125Ω/ 100 V
40 Watt
80 Watt
For operation in low impedance (4 ohm) mode, any loudspeaker (or combination) with an
impedance higher than 4Ωcan be connected.
4 Ω
8 Ω 8 Ω
OR
Example diagram low impedance connections
For operating using constant voltage (100V / 70V ) audio distribution systems, all speakers
shall be connected in parallel on the corresponding output terminals, non exceeding the
maximum wattage / minimum impedance of the amplifier.

12
Matching
transformer
Matching
transformer
Matching
transformer
Matching
transformer
Matching
transformer
Matching
transformer
Example diagram constant voltage connections
2) Connecting the audio sources
The next step is making the input signal connections. Depending of the source type and
signal level (microphone or line), they need to get connected to the matching inputs.
Before connecting, turn all the channel input and master volume controls on the front
panel of the amplifier fully counterclockwise (to their minimum setting) and put the gain
control trimmers on the rear panel in a central position. Then connect the sources to the
corresponding inputs and turn on the amplifier and the connected audio sources. After
approximately five seconds, the protection LED will stop illuminating.
Apply a signal to the inputs as it will be used in normal operation circumstances and turn
the channel input level control up about 50%. Slowly raise the master volume control till a
certain level until the desired sound level is achieved. Depending of the output level of the
connected music sources, the input gain might need adjustment. Adjust these trimmers on
the rear panel until the desired level is achieved.
For the best signal to noise ratio, the amplifier shall be set with the master volume controller
setting near maximum position and the peak signal indicator is illuminating frequently, without
illuminating the clip LED indicator. If the signal sounds too loud or distorted, use the input
level controls to attenuate as necessary to achieve the desired output level.

13
3) Priority & phantom power
The microphone input connection contains a priority (PRIO) and phantom power (PHNTM)
switch, whereby these functions can be enabled and disabled. When priority is switched on,
other connected audio sources will be eleminated once a signal is present on this input. It
also overriders the priority mute when enabled. The phantom power switch enables 15 Volts
phantom power supply for powering condenser microphones.
4) Priority mute contact
A priority mute contact allows complete muting of background music at presence of a contact
closure between both terminals. This contact is convenient for situations where a separate
emergency system is installed and complete background music muting is required at occasion
of a fire alarm. The emergency system contact outputs can be linked to this contact input.

14
Chapter 4
Additional information
Technical specifications
Inputs Mic in Type Balanced microphone
Connector 3-pin terminal block ~ 3.81 pitch
Sensitivity 0 dB ~ -50 dB
Other Phantom power (15V DC)
Priority
Line in Type Unbalanced stereo line
Connector RCA (2x)
Sensitivity +4 dB ~ -20 dB
Front line input Type Unbalanced stereo line
Combined with Line in (RCA)
Connector 3.5 mm stereo jack
Priority mute contact Type Priority mute
2-pin terminal block ~ 5.08 mm pitch
Outputs Volt / Imp 4 ΩCOM104 12.65 V
COM108 17.89 V
100 V COM104 250 Ω
COM108 125 Ω
70 V COM104 125 Ω
COM108 62.5 Ω
Connector 4-pin terminal block ~ 5.08 mm pitch
Frequency response 20 Hz - 20 kHz
Signal to Noise ratio > 90 dB
Total Harmonic Distortion + Noise < 0.5%
Crosstalk > 70 dB
Controls Master volume control
Two band tone control (output)
Input volume control
Indicators Power
Protect
Clip
-20 dB
Signal

15
Protection DC-Short Circuit
Over Heating
Over Load
Cooling system Convection cooled
Amplifier technology Class-D
Power supply Type Switching mode
Range 100-240 V AC - 50/60 Hz
Power consumption Idle 3.5 Watt
1/3 Rated power COM104 24 Watt
COM108 46 Watt
Dimensions 218 x 44 x 300 mm
Unit height 1 HE
Weight COM104 2.2Kg
COM108 2.35 Kg
Optional accessories MBS310 Rack mount kit
For single (10.5”) and side-by-side (19”) mounting

16
Notes