OWNER’S MANUAL
CPS 3 / CPS 4
CONTRACTOR PRECISION SERIES
DESCRIPTION
CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
Front Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Warranty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
DESCRIPTION
First of all, we would like to express our thanks and at the same time congratulate you on the decision to
buy one of our CONTRACTOR PRECISION SERIES power amplifiers.
Electro-Voice CONTRACTOR PRECISION SERIES amplifiers are made to meet the highest require-
ments of any on-the-road application. Thus they provide on-board protection against thermal and
capacitive overload, short-circuit and the occurrence of HF or DC at the output. Additionally, special
circuitry prevents the output-stage transistors from being damaged by Back-EMF. During soft start,
delayed switching of the power outputs is accomplished via relays and a limiter controls the initial current
inrush, preventing the mains fuse from being blown during the power-on operation.
The mechanical construction as well is carried out following the highest precision standards of the industry.
The robust steel chassis provides extreme rigidity and it is meant to live through any hard wearing condition
of a touring application. Thermal stability is guaranteed by two 4-Mode silently running fans that offer the
possibility to also use the amplifiers in a studio environment.
The extensive comparator circuitry constantly monitors the input and output signals and activates the
internal limiters whenever a non-linear operational state is encountered. This provides reliable protection
of the connected loudspeaker systems against overload and clipping. The sound quality of the CON-
TRACTOR PRECISON SERIES power amplifiers is superb. Using comprehensive dimensioned power
supply units with low-interference toroidal transformers gains a headroom that exceeds the nominal power
handling capacity by far. No V/I-Foldback-Limiter circuits are employed within the power amplifiers, making
it possible to operate the amps on complex loads up to ±90° phase angles without a problem.
The input facilities are carried out as balanced XLRF-type sockets while the Direct-Outs – on which the
carried-through signals are present – come as XLRM-type connectors. Using the Input Routing-switches
lets you determine if the CONTRACTOR PRECISION SERIES amplifiers are operated in DUAL (stereo)
or PARALLEL (monaural) mode; “mono-bridged” operation is also possible.
The dB-scaled level controls are to be found on the rear panel. These potentiometers guarantee precise
and reliable operation. The easy readable LED display offers quick optical information on the power
amplifiers’ momentary operational mode. For each channel individually the display shows whether they
are operational, a signal is present at the outputs, when the limiters are activated, and whether one of the
protection circuits has been engaged or not. The power outputs CANNEL A, CHANNEL B and BRIDGED
OUT are carried out as Speakon connectors. A ground-lift switch that separates the enclosure from the
appliance’s ground potential and therefore helps to eliminate ground noise loops and the mono bridged
mode switch are also located on the rear panel. In normal operation all CONTRACTOR PRECISION
SERIES power amplifiers can be used to drive loads down to 2 ohms; in bridged mode the minimal load
is 4 ohms. All amps are equipped with extremely silent running fans providing front-to-rear air circulation,
guaranteeing trouble-free operation even in smaller power amplifier rack systems.
Studying this owner’s manual carefully will provide you with further and more detailed information about
the CONTRACTOR PRECISION SERIES power amplifiers. Thus we recommend to keep on reading,
assuring you that the Electro-Voice CONTRACTOR PRECISION SERIES power amplifiers will provide
you with a lot of fun and satisfaction in your work.
9
FRONT PANEL
1. Level Control
To prevent unauthorized operation of the level controls on the CPS3 and CPS4, they are provided with
screwed-on protective cover lids. When shipped from the factory, the detented potentiometers are set to
their clockwise limits. Thus, the input signal is not attenuated. In case matching the input levels is required,
you first have to detach (unscrew) the cover lids to gain access to the potentiometers.
2. POWER ON INDICATION
This LED lights up when the mains switch is pressed. If it does not light up, the unit is not connected to
the mains or the mains fuse has blown.
3. INPUT INDICATION
This LED lights up if a signal is present at the power amplifier input. The indicator does not light up when
the input controls are turned down completely.
4. OUTPUT INDICATION
This LED lights up if a signal is present at the power amplifier output. The indicator goes off when the
speaker line has shorted or a protective circuit has been activated thus indicating that there is no signal
at the speaker output terminals.
5. LIMIT
This LED lights up if the limiter has been activated and the power amplifier is being operated at the clip
level. If the LED flashes briefly, this is not a cause for concern. If this LED is lit permanently, the volume
should be reduced to avoid overload damages to the connected loudspeaker systems.
6. PROTECT
When this LED lights up during operation, one of the protection circuits against over-temperature,
overload, shorted outputs, radio frequency interference or DC faults has been triggered. The cause of the
error e.g. a shorted loudspeaker line must be remedied. In case of overheating, wait a little until the
amplifier switches back to operating mode itself.
7. POWER Switch
The unit is switched on via the power switch. The loudspeaker outputs are switched on via delayed relays
so that no startup transients are audible. A current limiter prevents startup peaks on the mains line and
prevents the mains fuse from blowing.
10
REAR PANEL
POWER AMPLIFIER INPUTS
Parallel to the XLR-type inputs, output connectors are provided,
offering the opportunity to feed additional power amplifiers with the
same signal.
The inputs are electrically balanced with pin-assignment according to
the IEC 268 standard.
Pin-assignment of the XLR-type input connectors:
PIN 1: SHIELD
PIN 2: a, +
PIN 3: b, -
Input sensitivity is factory set to 0 dBu.
The power amplifier can be set internally to +6dBu input sensitivity or
to +26dBu gain.
INPUT ROUTING
PARALLEL MONAURAL
Setting the selector switch to the PARALLEL/MONO position puts the
channel A and channel B inputs in electrically direct parallel configu-
ration, leaving you still the possibility to control the channels’ level
settings separately, using the output controls A and B.
DUAL STEREO
When the selector switch is set to its DUAL/STEREO position both
channels are amplified individually.
11
REAR PANEL
POWER AMPLIFIER OUTPUT CONNECTORS
SPEAKON output connectors are provided for the power
amplifier channels A (left) and B (right).
The Bridged Out Connector for bridged operation is
sealed with a plastic cover to prevent connection errors.
LIMITER
The time constant of the built-in limiter to avoid overdri-
ving is adjustable. Position “SLOW” is the factory preset
and this should also be the normal position.
If the power amplifier is used as a MID/HI-frequency
amplifier in active multi-way systems, the limiter switch
should be set to “FAST”.
If the power amplifier is used as LOW-frequency ampli-
fier in active multi-way systems, the limiter switch should
be set to “SLOW”.
BRIDGED MODE
Slide switch to change from Normal Stereo mode to
Bridged mode. In Bridged mode the built-in power ampli-
fiers operate in “push- pull” and the double output voltage
from channel A and B appears at the Bridged output
connector. The phases of Channel A and B are in oppo-
site and therefore the individual channels must not be
used as loudspeaker outputs.
HI-LO-CUT FILTER
This filter attenuates subsonic and high frequency si-
gnals so that the power amplifiers are not modulated with
these signals. This switch should normally always be in
position ON. The OFF position is only for applications
where an upstream unit, e.g. a crossover or a equalizer,
has integrated HI-Cut and LO-Cut filters.
GROUNDLIFT SWITCH
Hum loops can be avoided with the groundlift switch. If
the power amplifier is operated together with other units
in one 19" rack, the switch should be in GROUNDED
position. If the power amplifier is used with units which
have different earthing potentials, the switch should be
adjusted to the UNGROUNDED position.
12
SPECIFICATIONS
Technical Specifications: CPS3, CPS4
Amplifier at rated conditions, both channels driven with 8 ohms loads, unless otherwise specified.
CPS3
CPS4
Load Impedance
8 W
4 W
2 W
8 W
4 W
2 W
Maximum Midband Output Power
THD=1%, 1kHz
560W 900W 1200W
500W 800W 1000W
1800W 2400W ———
72V
850W 1300W 1800W
750W 1200W 1500W
2600W 3600W ———
91V
Rated Output Power
THD< 0.1%, 20Hz ... 20kHz
Maximum Bridged Output Power
THD=1%, 1kHz
Maximum RMS Voltage Swing
THD=1%, 1kHz
Voltage Gain
at 1 kHz
37dB
39dB
Slew Rate
35V/µs
1300W
40V/µs
1850W
Power Consumption
at 1/8 maximum output power @ 4 W
Input Sensitivity
0dBu ( 775mV)
at rated output power @ 4 W, 1 kHz
THD at rated output power,
MBW=80kHz, 1 kHz
< 0.05 %
< 0.01 %
< 0.01 %
<-70 dB
IMD-SMPTE
60 Hz, 7 kHz
DIM30
3.15kHz, 15 kHz
Crosstalk
ref. 1kHz, at rated output power
Frequency Response
-1dB, ref. 1 kHz
13Hz ... 40kHz
10Hz ... 48kHz
20kW
Power Bandwith
THD=1%, ref. 1kHz, half power @ 4 W
Input Impedance
20Hz ... 20 kHz, balanced
Damping Factor
at 100Hz / 1kHz
>400 / >300
Signal to Noise Ratio
A-weighted
105dB
Power Requirements
Protection
230V, 50Hz ... 60Hz
Audio limiters, High temperature, DC, HF, Back-EMF,
Peak current limiters, Inrush current limiters, Turn-on delay
Front-to-Rear, 4-stage-fans
Cooling
Safety Class
I
Dimensions (W x H x D), mm
Weight
483 x 132.5 x 385.5
27kg
29kg
Retrofitting kit
Input Transformers
NRS 90176
13
BLOCK DIAGRAM
20
ABMESSUNGEN/DIMENSIONS
Abmessungen/Dimensions (in mm)
21
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