Electro-Voice CPS2.12, CPS2.4, CPS2.6, CPS2.9 User Manual

OWNER’S MANUAL

BEDIENUNGSANLEITUNG

CONTRACTOR PRECISION SERIES

CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Welcome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Unpacking and Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Scope of Delivery and Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Features and Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Responsibility of the User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Controls, Indicators and Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Operating Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Mains Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Groundlift. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

High Pass Filter (HPF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Power on delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Selecting the Mode Of Operation and Audio Output Cabeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Audio Input Cabeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Volume Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Standby Mode (POWER REMOTE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Fan Cooling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

RCM-810. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

INHALT

Einführung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Willkommen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Auspacken und Inspektion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Lieferumfang und Garantie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Eigenschaften & Beschreibung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Verantwortung des Betreibers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Bedienelemente, Anzeigen und Anschlüsse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Betriebsspannung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Netzschalter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Einbau . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Kühlung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Groundlift. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Hochpassfilter (HPF). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Einschaltverzögerung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Betriebsart (MODE) und Verkabelung des Audio-Ausgangs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Verkabelung des Audio-Eingangs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Betrieb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Eingangspegel-Regler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Anzeigen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Standby-Modus (POWER REMOTE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Lüfter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Optionen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

RCM-810. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Specifications/Technische Daten . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Mains Operation & Resulting Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Block Diagram / Blockschaltbild . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Dimensions / Abmessungen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

3

IMPORTANT SAFETY INSTRUCTIONS

The lightning flash with arrowhead symbol, within an
equilateral triangle is intended to alert the user to the
presence of uninsulated „dangerous voltage“ within the
product’s enclosure that may be of sufficent magnitude
to constitute a risk of electric shock to persons.

The exclamation point within an equilateral triangle is
intended to alert the user to the presence of important
operating and maintance (servicing) instructions in the
literature accompanying the appliance.

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. Clean only with a dry cloth.

7. Do not cover any ventilation openings. Install in accordance with the manufacture’s instructions.

8. Do not install near heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat.

9. Do not defeat the safety purpose of the polarized or the grounding-type plug. A polarized plug has two blades with on e 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. I t h e
provided plug does not fit into your outlet, consult an electrician for replacement of the obsolete outlet.

10. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they exit from
the apparatus.

11. Only use attachments/accessories specified by the manu facturer.

12. Use only with the cart, tripod, bracket, or table specified by the manufacturer, or sold with the apparatus. When a cart is used, use caution
when moving the cart/apparatus combination to avoid injury from tip-over.

13. Unplug this apparatus during lightning storms or when unu sed for a long period of time.

14. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way, such as power­supply cord or plug is damaged, liquid has been spilled or orbjects have fallen into the apparatus, the apparatus has been exposed to rain
or moisture, does not operate normally, or has been dropped.

15. Do not expose this equipment to dripping or splashing and ensure that no objects filled with liquids, such as vases, are placed on the
equipment.

16. To completely disconnect this equipment from the AC Mains, disconn ect the po we r supp ly cord plug from the AC rece pt a cle.

17. The mains plug of the power supply cord shall remain readily operable.

IMPORTANT SERVICE INSTRUCTIO NS

CAUTION: These servicing instructions are for use by qualified personnel only. T o reduce the risk of 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.

1. Security regulations as stated in the EN 60065 (VDE 0860 / IEC 65) and the CSA E65 - 94 have to be obeyed wh en servicing the appliance.

2. Use of a mains separator transformer is mandatory during maintenance while the appliance is opened, needs to be operated and is
connected to the mains.

3. Switch off the power before retrofitting any extensions, changing the mains voltage or the outpu t volta ge .

4. The minimum distance between parts carrying mains voltage and any accessible metal piece (metal enclosure), respectively between the
mains poles has to be 3 mm and needs to be minded at all times. The minimum distance between parts carrying mains voltage and any
switches or breakers that are not connected to the mains (secondary pa rt s) h as to be 6 mm and needs to be minded at all times.

5. Replacing spe cial components that are marked in the circuit diagram using the sec urity symbol (Note) i s only permissible wh en using
original parts.

6. Altering the circuitry without prior consent or advice is not legitimate.

7. Any work security regulations that are applicable at the locations where the appliance is being serviced have to be strictly obeyed. This
applies also to any regulations about the work place itself.

8.

All instructions concerning the handling of MOS-circuits have to be observed

NOTE: SAFETY COMPONENT (MUST BE REPLACED BY ORIGINAL PART)

.

4 Owner‘s Manual

WEEE RECYCLING/DISPOSAL INSTRUCTIONS

The Wheelie Bin symbol found on the product or in the manual indicates that this product must not be dis­posed of with other waste. It is in our category the manufacturer’s responsibility to proper ly dispose of their
waste electrical and electronic equipment (WEEE) at the end of its life. Due to the differences in each EU
country’s management of WEEE, please contact your local distributor. We are committed to facilitate our own
electronic-waste-management-system, for the free of charge return of all EVI Audio GmbH products: Telex,
Dynacord, ElectroVoice, Midas Consoles, KlarkTeknik and RTS. Arrangements are made with the dealer
where you purchased the equipment from, for the returning of all unusable equipment at no cost, to the fac­tory in Straubing, for environmental protective disposal.

CONTRACTOR PRECISION SERIES

1 Introduction

1.1 Welcome

Thank you for choosing an Electro-Voice CPS series amplifier. Please take time to consult this manual so that you can
understand all the features built into your Electro-Voice amplifier and fully utilize all its performance capabilities.

1.2 Unpacking and Inspection

Carefully open the packaging and take out the power amplifier. Inspect the power amp’s enclosure for damages that might
have happened during transportation. Each amplifier is examined and tested in detail before leaving the manufacturing site to
ensure that it arrives in perfect condition at your place. Please inform the transport company immediately, if the power
amplifier shows any damage. Being the addressee, you are the only person who can claim damages in transit. Keep the
cardboard box and all packaging materials for inspection by the transport company.
Keeping the cardboard box including all packing materials is also recommended, if the power amplifier shows no external
damages.

CAUTION:
Do not ship the power amp in any other but its original packaging.

When shipping the power amp, make sure to always use its original box and packaging materials. Packing
the power amplifier like it was packed by the manufacturer guarantees optimum protection from transport damage.

1.3 Scope of Delivery and Warranty

• 1 Power Amplifier

• 1 Owner‘s Manual (this document)

• 1 Mains Cord

• 1 Output connector, 4 pole

• 2 Input connector, 3 pole

• 1 Power Remote connector, 2 pole

• 1 Warranty Certificate
Keep the original invoice that states the purchase/delivery date together with the warranty certificate at a safe place.

1.4 Features and Description

Electro-Voice CONTRACTOR PRECISION SERIES Series amplifiers offer a package of reliable high output power, high
efficiency and legendary pro audio performance. They are the premium choice as system drive for a variety of Electro-Voice‘s
installation loudspeakers like e.g. EVI, FRi, FRX or Variplex families. Their comprehensive protection system includes circuitry
against overheating, overload, short circuit, HF and DC as well as back-EMF and inrush current. Loudspeakers are protected
by turn-on-delay relays.

1.5 Responsibility of the User

Speaker System Damage

CPS power amps provide extremely high power output that might be dangerous for human beings as well as for the
connected speaker systems. High output voltages can damage or even destroy the connected speaker systems, especially,
when the CPS amplifier is operated in bridged mode. Prior to connecting any loudspeakers, make sure to check the speaker
system’s specifications for continuous and peak power handling capacities. Even if amplification has been reduced through
lowering the input level controls on the amplifier’s front panel, it is still possible to achieve full power output with a sufficiently
high input signal.

Danger at the Loudspeaker/Power Outputs

CPS amplifiers are capable of producing dangerously high voltage output that is present at the output connectors. To protect
yourself from electric shock, do not touch any blank speaker cables during operation of the power amp.

Owner‘s Manual 5

CONTRACTOR PRECISION SERIES

WARNING:
The terminals marked with are hazardous live and the external wiring connected to these
terminals requires installation by an instructed person or the use of ready-made leads of
cords.

HF-Interference (FCC Information USA)

1. IMPORTANT: Do not modify this unit! Changes or modifications not expressly approved by the manufacturer could void the
user‘s authority, granted by the FCC, to operate the equipment.

2. NOTE:This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15
of the FCC Rules. These limits are designed to provide reasonable protection agains harmful interference in a residential
installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in
accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee
that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or
television reception, which can be
determined by turning the equipment off and on, the user is encouraged to try to correct the interference by
one or more of the following measures:

• Reorient or relocate the receiving antenna

• Increase the separation between the equipment and receiver

• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected

• Consult the dealer or an experienced radio/TV technician for help

This is a Class A product. In a domestic environment this product may cause radio inter­ferences in which case the user may be required to take adequate measures.

This Class A digital apparatus complies with Canadian ICES-003.

Cat appareil numérique de la classe A est conforme à la norme NMB-003 du Canada.

6 Owner‘s Manual

2 Installation

2.1 Controls, Indicators and Connections

Front View

1 Level Indicators for channels 1 and 2
2 Protections Indicator (PROTECT)
3 Muting Indicator (MUTE) for channels 1 and 2
4 Power On/Off Indicator (POWER)
5 Standby Indicator (STANDBY)
6 Remote Amplifier Indicator (IRIS-Net)
7 Mains Switch

CONTRACTOR PRECISION SERIES

Rear View

1 Mains Input
2
3 POWER REMOTE connector
4 Power On Delay selection switch (ON DELAY)
5 Expansion Slot
6 Audio Inputs (INPUT) for channels 1 and 2
7 Input Level Control (LEVEL) for channels 1 and 2
8 Power Amp Mode Switch (MODE)
9 Highpass Filter Switch (HPF)
10 Type Plate
11 Power Amp Outputs (CH 1, CH 2, BRIDGED)

Ground Lift Switch (CIRCUIT

⊥ TO CHASSIS SWITCH)

Owner‘s Manual 7

CONTRACTOR PRECISION SERIES

2.2 Operating Voltage

The power amplifier receives its power supply via the MAINS IN connector. Only the provided power cord may be used.
During installation, always separate the power amplifier from the mains. Connect the power amplifier only to a mains network,
which corresponds to the requirements indicated on the type plate.

Mains Operation & Resulting Temperature

The power drawn from the mains network is converted into output power to feed the connected loudspeaker systems and into
heat. The difference between power consumption and dispensed power is called power dissipation (Pd). The amount of heat

resulting from power dissipation might remain inside of a rack-shelf and needs to be diverted using appropriate measures.
The tables on page 31 allow the determination of power supply and cabling requirements. The tables are meant as auxiliary
means for calculating temperatures inside of a rack-shelf system/cabinet and the ventilation efforts necessary.
The column P

amount per hour. Power consumption is direct proportional for other mains voltages. The following conversion factors are
meant for easy conversion: 100V = 2.3; 120V = 1.9; 240V = 0.96

lists the leakage power in relation to different operational states. The column BTU/hr lists the dispensed heat

d

2.3 Mains Switch

The Mains Switch on the front panel separates the power amp from the mains. Turning the
Mains Switch to ON starts booting up the power amp. A soft start circuit compensates
mains inrush current peaks and thus prevents triggering AC mains fuse when switching on
the amplifier. Speaker system switch-on is delayed by approximately 2 seconds via output
relays, effectively suppressing any possible power-on noise, which otherwise might be
heard through the loudspeakers. PROTECT-LED light and fans are at high speed during
this delay. This indicates all protections are working fine.

2.4 Mounting

CPS amplifiers have been designed for installation in a conventional 19-inch rack case. Attach the power amp with its frontal
rack mount ears using 4 screws and washers as shown in following illustration.
Additionally securing the amplifier at the rear becomes necessary, if the rack case in which the power amplifier has been
installed will be transported. Failure to do so may result in damage to the power amplifier as well as to the rack case. Attach
the power amp as shown in the illustration using 4 case nuts and screws. Brackets for securing the power amplifier are
available as accessories.

2.5 Ventilation

As with all Electro-Voice power amps with fan cooling, the airflow direction is front­to-rear, obviously because there is more cold air outside of the rack case than
inside. The power amplifier remains cooler and dissipating the developing waste
heat in a specific direction gets easier. In general, setting up or mounting the
power amplifier has to be done in a way that fresh air can enter unhindered at the
front and exhausted air can exit at the rear. When installing the power amp in a
case or rack system, attention should be paid to these details to provide sufficient
ventilation. Allow for an air duct of at least 60 mm x 330 mm between the rear
panel of the power amplifier and the inner wall of the cabinet/rack case. Make
sure that the duct reaches up to the cabinet’s or the rack case’s top ventilation
louvers. Leave room of at least 100 mm above the cabinet/rack case for ventilation. Since temperatures inside of the cabinet/
rack case can easily rise up to 40 °C during operation of the power amp, it is mandatory to bear in mind the maximum
allowable ambient temperature for all other appliances installed in the same cabinet/rack case.

8 Owner‘s Manual

CONTRACTOR PRECISION SERIES

CAUTION:
Blocking/closing the power amp’s ventilation louvers is not permissible. Without sufficient
cooling/ventilation, the power amplifier may automatically enter protect mode. Keep ventilati­on louvers free from dust to ensure unhindered airflow.

Do not use the power amplifier near heat sources, like heater blowers, stoves or any other heat
radiating devices.

To ensure trouble-free operation, make certain that the maximum allowable ambient tempera­ture of +40°C is not exceeded.

For fixed amplifier installations in a device control room that incorporate a central air-cooling system or air conditioners,
calculating the maximum heat emission may be necessary. Please also take notice of the information on page 31.

2.6 Groundlift

The ground lift switch allows eliminating noise loops. When operating the power amplifier together with other
equipment in a rack case, setting the switch to the GROUNDED position is recommended. Set the switch to
UNGROUNDED, when the power amplifier is operated together with appliances with differing ground
potentials.

2.7 High Pass Filter (HPF)

The Hi-Pass filter (50 Hz, 18 dB/oct) allows effective attenuation of low frequency audio signals, which could
cause saturation problems with connected output transformers. Set the switch to the 50Hz position for
activating the High Pass Filter. Set the switch to the OFF position if no attenuation of low frequency audio
signals is required.

2.8 Power on delay

The ON DELAY switch at the amplifier rear panel allows selecting the power on delay time.
Following table shows possible switch settings and corresponding delay times.

ON DELAY Delay time

ON DELAY Delay time

(in s)

0 0.52 8 1.05
1 0.59 9 1.15
2 0.63 A 1.25
3 0.69 B 1.40
4 0.75 C 1.49
5 0.84 D 1.55

(in s)

6 0.90 E 1.61
7 0.95 F 1.69

Owner‘s Manual 9

CONTRACTOR PRECISION SERIES

2.9 Selecting the Mode Of Operation and Audio Output Cabeling

The MODE switch on the power amp‘s rear panel defines how the audio inputs handle the input signals. Possible settings are
DUAL, PARALLEL or BRIDGED.

DUAL

In DUAL mode, the two channels of the power amplifier work independent from each other. This mode
of operation is being used for all 2-channel applications, like stereo operation. Using the input level
controls on the power amp’s rear panel allows independently adjusting the channels’ amplification.

PARALLEL

In PARALLEL mode, the inputs of channel 1 and channel 2 are directly electrically linked. The audio
signal has to be applied to the input connectors of channel 1. Using the input level controls to
independently control the amplification of the two channels is still possible because only the channels’
inputs are linked. PARALLEL operation is the mode of choice, whenever the same input signal drives
multiple power amp channels of a large system installation.

CAUTION:
In PARALLEL mode, the input signal has to be fed to input channel 1 only.

See illustration right for connecting speakers in DUAL or PARALLEL
mode. The correct connection is also indicated at the amplifiers rear
panel.

BRIDGED

In BRIDGED mode both amp channels work in push-pull operation to provide doubled output voltage.
The audio signal has to be applied to the input connectors of channel 1, amplification is set via input
level control of channel 1 only.

CAUTION:
In BRIDGED mode, the input signal has to be fed to input channel 1 only. Amplification is set
via input level control of channel 1 only.
In BRIDGED mode operation, it is not allowable for the load connected to fall below a value of
4 ohms. Extremely high voltages can be present at the output. The connected speaker sy­stems must be able to handle such voltages. Make sure to completely read and fully observe
power rating specifications of the speaker systems to be used and to check them against the
output power capacity of the power amp.

Setting the MODE switch on the power amp‘s rear panel to BRIDGED lets the power
amplifier run in bridged mode operation and speaker connection has to be
established using pins 1+ und 2-, see illustration right. The correct connection is also
indicated at the amplifiers rear panel.

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2.10 Audio Input Cabeling

Inputs are electronically balanced. Whenever possible, using balanced audio signal feeds at the input of the power
amplifier is always preferred. Unbalanced connections should only be used if the cables are very short and no
interfering signals are to be expected in the vicinity of the power amplifier. In this case, bridging the screen
(shielding) and the pin of the inverting input inside of the connector is mandatory. Otherwise, a 6 dB drop in level
could result. Please also see following illustration. Due to their immunity against external interference sources,
such as dimmers, mains connections, HF-control lines, etc., using balanced cabling and connections is always
preferable.

Illustration 2.1: Balanced / unbalanced connection of input

CONTRACTOR PRECISION SERIES

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