PROCELLA AUDIO DA4280 User manual

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 1
DA4280 Power Amplier
www.procella.audio
[email protected]udio
User Manual V1.0

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 2
Statutory and Safety Notices
Please read the fhe following important technical, safety
and environmental notices before installing and using
your amplier.
Technical Notices
Procella Audio has taken all reasonable design and engineering
steps to ensure that the Procella DA4280 amplier always performs
satisfactorily in the intended application and environment and will
provide appropriate levels of support to ensure that all reasonable
customer needs and expectations are met. Such support however is
contingent on the following provisions.
1. The Procella DA4280 amplier is a Class-I product and should
be installed with a mains cable including the required earth
connection to comply with the Safety Class-I.
2. The Procella DA4280 amplier is intended for professional audio
applications and should always be installed and operated by
competent and qualied personnel. The Procella DA4280 amplier
damage or failure caused by installation or operational errors may
invalidate support, warranty or guarantees of performance.
3. The Procella DA4280 amplier is intended for professional use
only and are not suitable for use in locations where they may be
accessible to minors.
4. The Procella DA4280 amplier is intended to be used specically
for the amplication of audio signals and for connection to
conventional moving-coil loudspeaker systems. Use of the
Procella DA4280 amplier for amplication of signals outside the
audio band (20Hz to 20kHz) or to drive transducers other than
conventional moving-coil loudspeakers may invalidate support,
warranty or guarantees of performance.
5. The Procella DA4280 amplier should only be used within
professionally installed and congured audio systems comprising
input and output ancillary equipments that is known to be of an
appropriate level of performance and in good operating condition.
Any damage to, or unsatisfactory performance from, the Procella
DA4280 amplier caused by inadequate or failed input or output
ancillaries may may invalidate support, warranty or guarantees of
performance.
6. The Procella DA4280 amplier is intended to be installed and
operated indoor in a controlled environment (pollution degree,
PD2) within an ambient temperature range of 0°C to 40°C. the
Procella DA4280 amplier is not intended for use in heights above
2000 meters. The Procella DA4280 amplier installed or operated in
environments outside these limits may invalidate support, warranty
or guarantees of performance.
7. Procella Audio oers a limited warranty on all Procella Audio
amplier contingent on their installation and operation being
compliant with published Procella Audio documentation and/
or formally agreed standards. This warranty may not cover
malfunctions or failures due to incorrect or unauthorised
installation, inappropriate use or operation, unauthorised repair
or material modication, exposure to environmental conditions
outside published specications, mechanical damage and normal
wear and tear.
Safety and Environmental Notices
Note: The intent of the lightning ash with arrowhead symbol
in a triangle is to alert the user to the presence of uninsulated
“dangerous” voltage within the product’s enclosure that may be
of sucient magnitude to constitute a risk of electric shock to
humans.
Note: The intent of the exclamation point within an equilateral
triangle is to alert the user to the presence of important safety, and
operating and maintenance instructions in this manual.
WARNING! TO PREVENT FIRE OR ELECTRIC SHOCK, DO NOT
EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE.
Ambient Temperature Note: If this equipment
is operated in a conned or multiple rack
installation, the internal ambient operating
temperature may exceed the external ambient
temperature. It is important to ensure in these
circumstances that the published maximum
operating temperature for the equipment is
not exceeded.
Reduced Air Flow: Ensure that rack or other
closed installation does not restrict the cooling airow required
for safe and reliable operation of the equipment.

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 3
Statutory and Safety Notices
Important Safety Instructions
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Do not submerge the equipment in water or liquids.
7. Do not use any aerosol spray, cleaner, disinfectant or fumigant
on, near or into the equipment.
8. Clean only with a dry cloth.
9. Do not block any ventilation opening. Install in accordance
with the manufacturer’s instructions.
10. Do not install near any heat sources such as radiators, heat
registers, stoves, or other apparatus (including amplier) that
produce heat.
11. To reduce the risk of electrical shock, the power cord shall be
connected to a mains socket outlet with a protective earthing
connection.
12. Do not defeat the safety purpose of the polarized or
grounding type plug. A polarized plug has two blades with
one wider than the other. A grounding type plug has two
blades and a third grounding prong. The wide blade or the
third prong are provided for your safety. If the provided
plug does not t into your outlet, consult an electrician for
replacement of the obsolete outlet.
13. Protect the power cord from being walked on or pinched
particularly at plugs, convenience receptacles, and the point
where they exit from the apparatus.
14. Do not unplug the unit by pulling on the cord, use the plug.
15. Only use attachments/accessories specied by the
manufacturer.
16. Unplug this apparatus during lightning storms or when
unused for long periods of time.
17. Refer all servicing to qualied service personnel. Servicing is
required when the apparatus has been damaged in any way,
such as power supply cord or plug is damaged, liquid has been
spilled or objects have fallen into the apparatus, the apparatus
has been exposed to rain or moisture, does not operate
normally, or has been dropped.
18. The appliance coupler, or the AC Mains plug, is the AC mains
disconnect device and shall remain readily accessible after
installation.
19. Adhere to all applicable, local codes.
20. Consult a licensed, professional engineer when any doubt or
questions arise regarding a physical equipment installation.
Environmental Statement
This product complies with international directives,
including but not limited to the Restriction of
Hazardous Substances (RoHS) in electrical and
electronic equipment, the Registration, Evaluation,
Authorization and restriction of Chemicals (REACH)
and the disposal of Waste Electrical and Electronic
Equipment (WEEE). Consult your local waste disposal authority for
guidance on how properly to recycle or dispose of this product.

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 4
Introduction and Overview
1. Introduction
The Procella DA4280 power amplier has been designed to provide
congurable, consistent and reliable high performance audio
power amplication. Please read this installation and operation
manual fully before installing and using the amplier. If you have
any questions regarding amplier conguration, installation or
operation please contact the customer support department
at:[email protected]
Following this introduction, the manual is divided into sections
covering the following topics:
Overview
Carton Contents
Conguration
Installation
Connections
Operation
Maintenance
Frequently Asked Questions
2. Amplier Overview
The Procella DA4280 is a 1U rack format, four channel audio power
amplier that can drive both conventional low impedance (4Ω to
16Ω, - Low-Z) loudspeaker loads and constant voltage (70V/100V -
Hi-Z) transformer coupled loudspeaker loads. Each Procella DA4280
is preset at the factory for operation with 4 to 16 ohm loads. The
Procella DA4280 is capable of a maximum output of 280 Watts per
channel.
The Procella DA4280 amplier channel gain control knobs and
status indicators are located on the front panel. Signal input and
output connections are accomplished via ‘Euro Block’ connectors
and operational congurations are set up through a DIP switch
module located on the amplier rear panel. A rear panel GPIO
(General Purpose In/Out) connector is also provided that enables
some amplier functions to be controlled or monitored remotely,
including standby mode. The Procella DA4280 amplier has no
mains power switch and are operational as soon as mains power is
connected. The Procella DA4280 amplier should be connected to
switched mains sockets.
Amplier dimensions and features are illustrated in Diagram 1. The
Procella DA4280 amplier is primarily intended for installation in
an equipment rack but can also be under-desk or wall mounted, or
used free standing. It is fan-cooled and must be installed such that
ventilation apertures are not obstructed.
3. Carton Contents
The Procella DA4280 amplier are shipped in a cardboard carton
containing the amplier unit, a mains cable appropriate for the
sales territory, an accessory pack, and a document pack. The full
contents is listed below.
• Procella DA4280 amplier unit
• Mains power cable
• 4x XLR to Euroblock cables
• Input connector x 4
• GPIO socket connector
• Output connector x 4
• Adhesive rubber feet x 4
• Document pack
Optional accessories
• Pair of Rear Support Brackets
292 mm
11.5 in
440 mm
17.3 in
44 mm
1.7 in
80 mm
3.1 in
25 mm
1 in
Diagram 1
The Procella DA4280 dimensions.
Shaded area denes ventilation space.

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 5
Conguration and Installation
4. Conguration
The Procella DA4280 amplier operational conguration is set up
through selections made on a rear mounted DIP switch module.
A GPIO (General Purpose In/Out) connector is also provided that
enables some amplier functions to be controlled or monitored
remotely.
4.1 DIP Switch Conguration
The DIP switch module is illustrated and its
functions described in the adjacent matrix.
DIP switch options are selected (ON) when
the switch is in the UP position. DIP switches
should only be operated when the amplier
is disconnected from mains power.
Note: Use a small at blade screwdriver
blade to operate the DIP switches.
Note: Channels operating in Hi-Z mode
have a 80Hz second order (12dB/octave)
high-pass lter automatically inserted
into the signal path in order to prevent
speaker transformer core saturation.
OFF ON
SWITCH 1 Channel 1 in Low-Z mode Channel 1 in Hi-Z mode
SWITCH 2 Channel 2 in Low-Z mode Channel 2 in Hi-Z mode
SWITCH 3 Channel 3 in Low-Z mode Channel 3 in Hi-Z mode
SWITCH 4 Channel 4 in Low-Z mode Channel 4 in Hi-Z mode
SWITCH 5 70V Hi-Z mode
(for channels in Hi-Z mode)
100V Hi-Z mode
(for channels in Hi-Z mode)
SWITCH 6 Input ganging 1: All Input ganging 1:1
SWITCH 7 GPIO standby polarity NO
(Normally Open)
GPIO standby polarity NC
(Normally Closed)
SWITCH 8 Front panel control locked. Front panel control unlocked.
4.2 GPIO Functions
The GPIO connector
is illustrated and its
functions described in
the adjacent matrix.
Note: The GPIO
connector must
not be used for any
unintended purpose.
Amplier damage may
result from incorrect
use of GPIO.
Note: In order to
conform to EMC
specications,
shielded cable must
be employed when
connecting external
volume control
potentiometers to the
GPIO connector.
FUNCTION NOTES
GPIO GND (1) Ground reference for all GPIO pins
GPIO V12 (2) Channel 1 & 2 auxiliary gain control.
Connect to a potentiometer (>10kΩ)
wiper between the VCC and GND pins.
The maximum level available when
using GPIO control is dened by the
front panel gain control setting.
GPIO V34 (3) Channel 1 & 2 auxiliary gain control
(four channel amplier only).
Connect to a potentiometer (>10kΩ)
wiper between the VCC and GND pins.
The maximum level available when
using GPIO control is dened by the
front panel gain control setting.
GPIO VCC (4) Control voltage output.
Provides a 3.3Vdc control output
(100Ω output impedance) for up to
two volume control potentiometers
(>10kΩ).
GPIO STB (5) Remote standby control. Pull to GND to engage standby mode.
GPIO GPO (6) System status indication.
OV DC indicates normal status, +3.3Vdc
indicates one or more channels in
protection mode.
1 2 3 4 5 6

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 6
Conguration and Installation
5. Installation
Note: It is important in all installations that
the amplier mains supply switch is easily
accessible.
5.1 Rack Mounting
The Procella DA4280 amplier is shipped with
rack mount ‘ears’ attached as illustrated in
Diagram 2a and is primarily intended to be
installed in an equipment rack. The installation
and equipment rack should be congured to
provide appropriate ventilation airow space
around the sides and rear of the amplier as
illustrated in Diagram 1. Ventilation airow space
of at least 25 mm (1 in) should be maintained
along at least one side of the amplier at all
times. Ventilation apertures are also located
on the rear panel of the amplier and must
not be obstructed. It is important to retain
at least 80 mm (3.1 in) free space for airow
behind the amplier rear panel.
In addition to rack mount ears, optional rack
mount rear support hardware is available
and can be attached to the amplier. Rear
support hardware may be appropriate
if the amplier is to be used in a mobile
rack or potentially be subject to signicant
movement. Diagram 2b illustrates the use of
rack mount rear support hardware.
Rack Ear +
2 x M4 x 8 csk
Diagram 2a
Procella DA4280 rack ears. 2 positions.
Rear Support + Button +
1 x M4 x 8
Diagram 2b
Procella DA4280 rear support hardware.
2 positions.

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 7
Connections
6. Connections
Note: The micro USB socket located
on the amplier rear panel is
present for service and diagnostic
purposes only.
The Procella DA4280 amplier
rear panel connection sockets are
illustrated in Diagram 3.
6.1 Mains Power Connection
The Procella DA4280 amplier has
a power factor corrected universal
power supply and can be used with mains input voltage from
100V AC to 240V AC, 50/60Hz. Use the mains cable supplied
with the amplier and connect it to a switched mains supply.
The power consumption of the Procella DA4280 amplier is
300W.
The Procella DA4280 amplier has no mains power switch and
are operational as soon as mains power is connected. Ensure that
all signal, GPIO and output connections are made and that all DIP
switch options are selected appropriately before connecting the
amplier to mains power.
6.2 Input Connections
The Procella DA4280 amplier inputs are of balanced, line level
format with a full output power sensitivity of +5.5dBu in 8Ω and
Hi-Z mode and +2.5dBu in 4Ω mode. Input signal levels up to
+24dBu can be handled without input clipping.
Input connections to the the Procella DA4280 amplier are
achieved via male ‘Euro Block’ connectors. Connecting cables to the
supplied female input connectors is illustrated in Diagram 4a.
6.3 Output Connections
Output connections from the Procella DA4280 amplier are
achieved via male ‘Euro Block’ connectors. Ensure that speaker
connection polarity is correct throughout the installation: positive
(+) amplier terminals should always be connected to positive
speaker terminals and negative (–) amplier terminals always
connected to negative speaker terminals.
No bridge mode - The Procella DA4280 employs an inherently
bridged Class D output topology; therefore, an alternate bridge
mode output connection should NOT be used, even when only one
loudspeaker (such as a subwoofer) will be connected. Under no
circumstances should the amplier connection be bridged, as this
may cause undesired operating performance or damage.
Together with DIP switch conguration, the output connector
blocks provide connection options that enable channel
Cable Gauge Table
Low-Z installations. 8Ω loads
independent selection of Hi-Z or Low-Z mode. Connecting cables
to the supplied female output connector, and the selection of Hi-Z
or Low-Z connection options, are illustrated in Diagrams 4b and 4c
respectively.
6.4 GPIO Connections
If any GPIO functionality is required, cables will need to be
connected to the supplied GPIO connector. Connecting cables to
the supplied female GPIO connector is illustrated in Diagrams 4d.
6.5 Speaker Cable Gauge
Speaker connection cable gauge should be chosen appropriately
to reect the type of installation. The adjacent tables specify the
appropriate cable gauge for less than 0.5dB cable loss with dierent
installation types and cable lengths.
Cable Cross Section
(mm2)
Cable Gauge
(US)
Max Cable Length
(metres, 8Ω load)
2.5 ≈14 up to25m (80’)
4.0 ≈12 25 - 45m (80’ - 150’)
100 - 240 VAC~
50 - 60Hz / 150W
AC MAINS
INPUT
GPIO
DIP
8
7
6
5
4
3
2
1
V12
V34 VCC
STB
GPO
CH1
CH3
CH2
CH4
MAINTENANCE
CH1
CH3
CH2
CH4
OUTPUT
CLASS 2
WIRING
CLASS 2
WIRING
HiZ HiZ
NC
LoZ LoZ
DESIGNED AND ENGINEERED IN DENMARK - MANUFACTURED IN CHINA
Input
Channel 1 & 2
Output
Channel 1
GPIO
Input
Channel 3 & 4
Output
Channel 2
Output
Channel 3
Output
Channel 4

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 8
5 mm
5 mm 5 mm
Hi-Z
Low-Z
Connections
Diagram 4a
Cable connections
to the input connector.
Diagram 4c
Example output connections.
Channel 1: Low-Z connection illustrated
Channel 2: Low-Z connection illustrated
Channel 3: Low-Z connection illustrated
Channel 4: Low-Z connection illustrated
Note: DIP switch options must be set appropriately.
Diagram 4b
Cable connections
to the output connector.
Diagram 4d
Cable connections
to the GPIO connector.
The exclamation point printed next to the output terminals of the Procella DA4280 amplier is, in addition to the
CLASS 2 WIRING text, intended to alert users to the risk of hazardous voltages. Output connectors that could pose
a risk are marked with the exclamation point. Do not touch the output terminals while the amplier is switched on.
Make all connections with the amplier switched o.

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 9
Operation
7. Operation
Once all connections have been made and DIP switches set, the
Procella DA4280 amplier can be connected to mains power. After
a short delay the front panel standby indicator will illuminate green
to indicate normal amplier operation. Indicators adjacent to each
channel gain control knob illuminate in dierent colours to indicate
specic amplier states:
Green: Signal present (> -45dB)
Orange: Output limiter active (0dB)
Red: Input overload, output protection operational or
amplier fault
Standby indicator
Gain adjust and signal indicator – Channel 4
Gain adjust and signal indicator – Channel 3
Gain adjust and signal indicator – Channel 2
Gain adjust and signal indicator – Channel 1
Diagram 5
Procella DA4280
front panel.
Set the channel gain controls appropriately in respect of the input
signal level and required speaker volume. Diagram 5 illustrates the
front panel controls and indicators.
The Procella DA4280 amplier outputs will mute if no input signal
is present for 10 minutes, and the amplier will switch automatically
to standby mode if no signal is present on any input for more than
25 minutes. Standby mode can also be triggered remotely via a
switch connected between the STB and GND GPIO connector pins.
In both cases the front panel standby indicator will illuminate red.

Specications subject to change. | ©2021 Procella Audio Svenska AB, Procella Audio USA, LLC. All rights reserved. | V1.0 2021/08 10
Specications
Model the Procella DA4280
Channels 4
Output power @
4Ω/8Ω/70V/100V*
All channels driven
280 W
Output power @
4Ω/8Ω/70V/100V*
Single channel driven
280 W
Output power @ 16Ω
All channels driven 140 W
Power Consumption 300 W
Dimensions 44.5 x 440 x 292 mm
(1.75 x 17.32 x 11.50 in)
Weight 3.9 kg (7.9 lbs)
Output Circuitry UMAC™ Class D - full bandwith PWM modulator with ultra-low distortion
Output Voltage 140 Vp / 280 Vpp (unloaded)
Max. Output current 25A peak
Signal To Noise-Ratio > 100 dB (A-weighted, 20 Hz - 20 kHz, 8 Ω load)
THD+N (typical) < 0.05 % (20 Hz - 20 kHz, 8 Ω load, 3 dB below rated power)
Frequency Response 20 Hz - 20 kHz (+0/-0.25 dB (8 Ω load, 3 dB below rated power)
Protection Circuits Short circuit protection, DC protection, under voltage protection, temperature protec-
tion, overload protection
Power Supply UREC™ universal mains switch mode power supply with Power Factor Correction (PFC)
and integral standby converter
Operating
Voltage/Frequency. Universal Mains, 100-240V, 50-60Hz
Standby Consumption < 0.5 W (Energy Star & ErP 1275/2008/EC compliant)