Coda Audio
C25 Power Amplifier
User Guide version 1.0
Contents
EC Declaration of Conformity
Important Safety Instructions
Installation
Electrical
Mechanical
EMC (RF Emissions)
Features
3
4
4
4
5
5
5
-3 dB Indicators
PRC
Gain/Sensitivity Settings
6
6
6
Level controls
Bar Signal indicators
-3dB indicator
Limiters
PRC indicators
Temperature control
Fault indicators
Bridged LED
8
8
8
8
8
8
9
9
Introduction
Connections
Inputs
Outputs
Bridged Operation
Link Socket
Operation
Switching on
Panel Controls and Indicators
Maintenance
Technical Specification
Power requirements
Appendix
Table of PRC settings and resulting
2
6
7
7
7
8
8
8
8
8
9
10
10
11
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C25 User Guide Version 1.0
C25 User Guide Version 1.0
3
Important Safety Instructions
1)
Read these instructions.
2)
Keep these instructions.
3)
Heed all warnings.
4)
Follow all instructions.
5)
Do not block any ventilation openings and install in accordance with the manufacturer’s
instructions.
6)
Unplug this apparatus during lightning storms or when unused for long periods of time.
7)
Clean only with a dry cloth.
8)
Do not use this apparatus near water; the apparatus shall not be exposed to dripping or
splashing and no objects filled with liquids, such as vases shall be placed on the apparatus.
9)
Refer all servicing to qualified service personnel. Servicing is required when the apparatus
has been damaged in any way, such as if the 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.
Installation
Electrical
This amplifier has been manufactured to comply with your local power supply requirements but,
before connecting the unit to the supply, ensure that the voltage (printed on the rear panel) is correct.
Make sure power outlets conform to the power requirements listed on the back of the unit. Damage
caused by connecting to improper AC voltage is not covered by the warranty.
Safety Warning
Where a mains plug or appliance coupler is used as the disconnect device, it should remain readily
operable.
Where the amplifier is mounted in a rack and permanently connected to the mains, then the rack
should be installed with a readily accessible connector or an all pole circuit breaker.
This unit is fitted with a 3-wire power cord. For safety reasons the earth lead should not be
disconnected in any circumstance. If ground loops are encountered, consult the section on ‘Input
Connections’ later in this manual.
The wiring colours are:
230 V Areas:
Warning:
4
Earth = Green and Yellow
Neutral: = Blue
Live: = Brown
120 V Areas:
Earth: = Green
Neutral: = White
Live: = Black
To reduce the risk of fire or electric shock, do not expose this apparatus to rain or
moisture.
C25 User Guide Version 1.0
To avoid electrical shock do not remove covers. Refer all servicing to qualified personnel.
Do not use the unit if the electrical power cord is frayed or broken.
The power supply cords should be routed so that they are not likely to be walked on or pinched by
items placed upon or against them, paying particular attention to cords and plugs and the point
where they exit from the appliance.
Always operate the unit with the AC ground wire connected to the electrical system ground.
Precautions should be taken so that the means of grounding of a piece of equipment is not defeated.
Do not remove the lid. Removing the lid will expose you to potentially dangerous voltages. There are
no user serviceable parts inside.
Mechanical
To ensure that this equipment performs to specification, it should be mounted in a suitable rack or
enclosure as described below. Like all high power amplifiers, it should be kept away from other
equipment which is sensitive to magnetic fields. Also, this amplifier may suffer a substantial reduction
in performance if it is subjected to, or mounted close to equipment which radiates high R.F. fields.
When mounting the amplifier in a rack or enclosure, ensure that:
1.
The rear of the unit is adequately supported. The brackets which are supplied fit standard 19
inch (483mm) rack mounting systems. The front panel is not capable of supporting the unit
on its own.
2.
There is adequate ventilation. The cooling fans suck cool air in through the front and blow hot
air out at the rear of the unit through the ventilating grills. If this air is not allowed to escape,
overheating will occur. Take care when mounting other equipment in the same rack.
3.
The rack unit has a separate earth connection (technical earth).
Also see maintenance section page 9.
EMC (RF Emissions)
The high frequency resonant converters in the C Series amplifiers have been designed to have very
low radio frequency (RF) emissions, which can cause interference with other equipment. In order to
reduce the influence of this, Power Amplifiers should be mounted in a dedicated metal rack
enclosure, which does not include equipment which may be sensitive to RF radiation, such as radio
microphone receivers.
Features:
The C-Series introduces three user-controlled features previously not seen on Coda Audio amplifiers:



C25 User Guide Version 1.0
-3 dB indicators
Power reduction control (PRC)
User-settable gain/sensitivity (internal)
5
The latest version now also has improved signal level indication with 3 green LEDs in a ‘bar chart’
format. This gives a much clearer indication of level to the operator. The -3 dB and Limit LEDs
continue the bar format.
-3 dB Indicators
Part of the front panel signal level display, they will light up when the signal is approximately 3 dB
below the limiting point. The limiting point is set during production to be at the onset of clipping. The
response times of the -3 dB indicators (YELLOW) are faster than those of the limit indicators
(ORANGE).
PRC
This enables the user to set a maximum output power level below the rated output of the amplifier.
This reduction is controlled by switches on the rear panel, 2 per channel. Each channel has an LED
indicator (GREEN) active when either PRC switch is selected. A full table of PRC settings and the
resulting outputs are given in the Appendix. The possible settings are: -2dB, -4dB, -6dB. This relates
to the maximum output of the amplifier:
E.G.
C25
Max. power into 4 Ohm
-2 dB PRC setting
-4 dB PRC setting
-6 dB PRC setting
=
=
=
=
1250 W/+39 dBu
800 W/+37 dBu
525 W/+35 dBu
350 W/+33 dBu
In bridged mode the Channel A PRC circuit operates over both Channel A and B. In this mode
Channel B PRC is not used and is out of circuit.
Gain/Sensitivity Settings
Gain settings are changed internally by simple jumper links. Two rows of pins marked - GAIN A and
GAIN B - are situated on the input PCB (PCB701). A jumper link sets the gain and the settings are as
follows:
Link 1 & 2
Link 3 & 4
Link 2 & 3
Note:
gives
gives
gives
32dB gain
26dB gain
approx. 33dB gain
=
6dBu/1.5V sensitivity C25
Factory setting is normally link 1 & 2 = 32dB gain.
Setting higher gain does not change the maximum available power but changes the level of
signal input to achieve maximum power. In any case, provided that the input signal is less
than 20dBu/7.7V, the built in limiter circuit will prevent distortion within the amplifier.
The gain should be set to match the signal from the source, e.g. mixer, controller, equaliser
etc.
Introduction
The C25 are no compromise, high quality, class AB power amplifiers. There is no dynamic switching
of the audio or power rails, thus ensuring optimum sonic performance.
Fan speed is varied as required to keep the amplifier within its temperature limits. Signal limiters are
included to protect speakers from clipped signals.
The amplifiers include full DC and short circuit protection to ensure trouble-free service even in
‘harsher’ environments.
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C25 User Guide Version 1.0
Connections
Inputs
The inputs are made via 3-pin XLR connectors, which are electronically balanced and should be
connected via a high grade twin core screened cable, as follows:
PIN1 - Screen (see note)
PIN2 - Hot (signal +)
PIN3 - Cold (signal -)
For Unbalanced Inputs
The amplifier is designed to operate with fully balanced equipment and ground loops or loss of
performance may be experienced if connected to unbalanced sources. If it is unavoidable however,
the following wiring should be used. The cable should still be twin core plus screen.
PIN1 PIN2 PIN3 -
Screen - connected to the chassis of the unbalanced equipment - or left disconnected at the
unbalanced end.
Signal Hot
Signal Cold
Note: This amplifier is wired to the latest industry recommendations. PIN1 is connected directly to the
chassis/mains earth. If ground loops (mains hum) are encountered remove the screen
connection from the other end of the cable and leave it open circuit. If problems persist, consult
your dealer/supplier.
Do not tamper with or alter any ground (earth) connections inside the amplifier.
For bridged operation input should be made to channel A only and the rear panel switch set for
bridged mode.
Outputs
The speaker outputs are via Neutrik™ Speakon connectors. Only 2 of the 4 poles are used. 2-pole
(NL2FC) or 4-pole (NL4FC) connectors can be used.
Terminations are as follows :Note:
Pin +1 = +ve
Pin -1 = -ve
1. Negative (-ve) output terminals must not be joined together, since they are not both at 0V.
2. Because the currents involved are very high, the speaker cables should conform to the
following minimum requirements, otherwise the losses will cause the cables to get hot and
audio power will be reduced:
C25 - 16A all into 4 Ohm speaker loads
Note:
Do not connect the inputs/outputs to any other voltage source such as a battery, mains
source or power supply, regardless of whether the amplifier is turned on or off.
Do not run the output of any amplifier channel back into another channel’s input and do not
parallel or series-connect an amplifier output with any other amplifier output.
C25 User Guide Version 1.0
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Bridged (Mono) Operation
Use centre Speakon connector marked ‘BRIDGED’ and connect as follows:
For bridged operation:
Pin
Pin
12+
For 4-pole connection to both channels:
(Bridged switch de-selected [ie Out])
Pin 1+
Pin 1Pin 2+
Pin 2-
=
=
-ve (Ch A)
+ve (Ch B)
=
=
=
=
Ch. A +ve
Ch. A -ve
Ch. B +ve
Ch. B -ve
When operating in bridged mode, the minimum impedances are doubled. The minimum load in
bridged mode is: 4 Ohm.
Link Socket
Each channel is provided with a 3-pin XLR connector marked ‘LINK’ which allows the input signal to
be linked to further amplifiers etc. The connections are the same as for the input XLR.
Operation
Switching on
At ‘switch-on’ the protection circuit will initially activate whilst the circuits stabilize. Assuming no faults
are detected after a few seconds only the ‘POWER’ LED (and ‘SIGNAL’ indicators if signal is applied)
will illuminate.
Panel Controls and Indicators
Level controls
These are analogue controls allowing precise level settings. Note that in ‘BRIDGED’ mode only
‘channel A’ control is active.
Signal Indicators (3 Green LEDs)
These are active from a minimum output level of approximately 10 Watts and are only an indication of
signal level.
-3dB Indicators (yellow LED)
These are active when the signal is 3dB below the limiting level.
Limiters (Red LED)
The C25 incorporates signal limiters, which are preset to prevent clipping with high levels of drive.
The amber LEDs on the front panel illuminate to indicate operation of the limiters.
PRC Indicators (green LED)
These indicate when the PRC circuit for that specific channel has been selected with the rear panel
switches.
Temperature Control
The cooling fans respond to temperature sensors within the unit to maintain a safe operating
temperature. In the event of excessive temperature, the protection circuit will operate, disabling the
output. The red ‘AUDIO-PROTECT’ (A/P) LED will indicate this condition. (See fault indicator.)
The C25 has four fans connected permanently with variable speed and a jumper link to enable them
from cold.
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C25 User Guide Version 1.0
Normal dynamic signals will not cause the amplifier to overheat unless the ventilation is
inadequate. (See installation section and maintenance section.)
Fault Indicator (Audio Protection – red LED)
If the outputs are shorted or if DC is present, the protection circuit will disengage the outputs and the
A/P LED will illuminate. The amplifier will continue to be monitored and depending on the type of
fault, will either reset after the fault has cleared or require manual resetting by switching off at the
mains switch and then on again after a few seconds. (See also temperature control above.)
Temperature related faults will reset once the unit has cooled sufficiently.
Output short circuits will require manual reset after clearing the fault.
Bridged LED (green)
This indicates the position of the switch on the rear panel and is illuminated when bridged mode is
selected with the switch pressed in.
Maintenance
(ENSURE THAT ELECTRICAL POWER TO THE UNIT IS DISCONNECTED BEFORE CARRYING OUT
ANY MAINTENANCE.)
The filter behind the air intake apertures on the front of C25 should be cleaned or replaced
periodically, e.g. 6-12 months. (Filters in amplifiers located in more 'dirty' atmospheres may require
more frequent maintenance.) The filters can be removed and replaced without removing the blue
front panel. When re-fitting the filter ensure that it covers the grill area completely. (A screwdriver or
pen can be used to position the filter behind the front grill.) The filter should be 'dry' cleaned, using a
vacuum cleaner preferably or washed and dried thoroughly. Running the unit without a filter is not
recommended unless it is within a 'clean room'. Replacement filter material is available.
No other regular maintenance is required.
If you have any doubt about carrying out this procedure, refer to a service engineer or contact
your dealer.
If your amplifier develops a fault, please refer to your supplier for service and technical
support. Do not attempt to repair the fault yourself as this will invalidate the warranty.
C25 User Guide Version 1.0
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Technical Specification
Output power (Watts RMS)
per channel
8 Ohm @ 1 kHz
4 Ohm @ 1 kHz
2 Ohm @ 1 kHz
650
1250
2200
8 Ohm @ 1 kHz
4 Ohm @ 1 kHz
2500
4400
4 Ohm 1 kHz
20 Hz-20 kHz
<0.008 %
<0.03 %
Mono Bridged
THD @ rated power
Input CMRR
>90 dB
Hum & Noise
-105 dB
Gain (selectable)
+32 dB/+26 dB/+33 dB
Sensitivity for rated output (4 Ohm)
+7 dBu/+13 dBu/+6 dBu (1.5V)
Damping Factor 1 kHz, 8 ohms
>400
Frequency response
20 Hz-2 0kHz +0/-0.5 dB
Input impedance
(actively balanced)
20 kOhm
Dimensions (mm) - 2U
88 x 482 x 428
Weight
10kgs
Power requirement
230 VAC @ 12amps max
115 VAC @ 18 amps max
Power requirements
The C25 can be supplied for nominal mains voltage of 115 V or 230 V.
An internal link can be set to either 100 V or 120 V for the 115 V version and 220 V or 24 0V for the
230 V version. Normally these are set to 120 V and 240 V respectively.
This amplifier will only operate to its very high specification if it is installed and operated as
described in this manual.
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C25 User Guide Version 1.0
Appendix
Table of PRC settings and resulting Output
Output per Channel (Watts)
Bridged Mode (Watts)
Max Power into 4 Ohm
-2 dBu PRC Setting
-4 dBu PRC Setting
-6 dBu PRC Setting
1250
800
525
350
4400
2800
2000
1300
Max Power into 8 Ohm
-2 dBu PRC Setting
-4 dBu PRC Setting
-6 dBu PRC Setting
680
430
280
180
2500
1600
1050
700
Max Power into 2 Ohm
-2 dBu PRC Setting
-4 dBu PRC Setting
-6 dBu PRC Setting
2200
1400
1000
650
N/A
N/A
N/A
N/A
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Coda Audio GmbH
Boulvard der EU 6
30539 Hannover
Germany
Phone: +49 (0) 511 – 866 55 888
Fax: +49 (0) 511 – 866 55 887
E-Mail: contact@codaaudio.com
Website: www.codaaudio.com