ATC P4 User Manual

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GYPSY LANE, ASTON DOWN, STROUD, GLOUCESTERSHIRE, UK, GL6 8HR. [phone] [phone]

[e-mail] —— WWW.ATC.GB.NET

PP4

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S A F E T Y I N S T R U C T I O N S

RISK OF ELECTRIC SHOCK

DO NOT OPEN

1. Read instructions – all the safety and operating instructions should be read before the appliance

2. Retain these instructions – the safety and operating instructions should be retained for future reference.

3. Heed warnings – all warnings on the appliance and in the operating instructions should be adhered to.

4. Follow instructions – all operating and other instructions should be followed.

5. Water and moisture – the appliance should not be used near water, for example near a bathtub, washbowl,

6. Ventilation – the appliance should be situated so that its location or position does not interfere with its proper

7. Heat – the appliance should be situated away from heat sources such as radiators, stoves or other appliances

8. Power sources – the appliance should be connected to a power supply only of the type described in the

9. Power cord protection – power supply cords should be routed so that they are not likely to be walked on or

10. Cleaning – the appliance should be cleaned only as recommended by the manufacturer.

11. Unattended periods – the power cord of the appliance should be unplugged from the outlet when left unused

12. Object and liquid entry – care should be taken so that objects do not fall into and liquids not spilled into the

is operated.

kitchen sink, laundry tub, in a wet basement or near a swimming pool etc..

ventilation. For example the appliance should not be situated on a bed, sofa, rug or similar surface that may
block the ventilation openings. Similarly, the appliance should not be built into an installation, such as a
bookcase or cabinet, that may impeded the flow of air through the ventilation openings.

that produce heat.

operating instructions or as marked on the appliance.

pinched by items placed upon or against them, paying particular attention to cords at plugs, convenience
receptacles and the point where they exit the appliance.

for a long period of time.

inside of the appliance.

13. Damage requiring service – the appliance should be serviced y qualified service personnel when:
i. the power supply cord or the plug has been damaged
ii. objects have fallen or liquid has been spilled into the appliance
iii. the appliance has been exposed to rain or other serious liquid exposure
iv. the appliance does not appear to operate normally or exhibits a marked change in performance
v. the appliance has been dropped or the cabinet damaged

14. Servicing – the user should not attempt to service the appliance beyond those measures described in the

15. Grounding or polarisation – the precautions that should be taken so that the grounding or polarisation means

operating instructions. All other servicing should be referred to qualified service personnel.

for the appliance is not defeated.

1

I N T R O D U C T I O N

Welcome to the world of ATC monitors, they are a result of many years research and
development and given the right opportunity will deliver exceptional audio performance. Please
read the following manual carefully – it will help you realise their full potential.

Founded in 1974, ATC has had one objective and that is to build the finest loudspeakers money

can buy. Bill Woodman, the company’s founder and Managing Director, originally had the idea for

our monitors in 1970. He felt that both HI-FI loudspeakers and studio monitors needed
improvement. The best HI-FI loudspeakers have reasonable sound quality and limited dynamic
range, while studio monitors have plenty of dynamic range but relatively poor sound quality. This
was true then and still today.

The ATC system will equal, or better, the acoustic performance of the best HI-FI, and has the
dynamic range of big horn loaded studio monitors.

To achieve this requires some of the world’s most expensive and highly specified hand made

drive units, and the sympathetic design of appropriate audio electronics. All major components are
designed and manufactured by ATC.

ATC monitors have been available in recognisable form since 1980, followed by a breakthrough in
1985 when the top end systems became active, with the introduction of the active amplifier pack
developed by Tim Isaac. Although it is generally accepted that active systems have the potential
for superior audio performance, they have been slow to catch on in HI-FI circles where
considerable sums of money have been spent on amplifiers.

The active approach allows the use of one amplifier for each loudspeaker drive unit. One each for
the tweeter and the bass, each amplifier is rated according to the drive unit it is attached to,
allowing the tweeter and bass amplifier to be set to run class A to high levels. The filter networks
within the amplifier process the signal for each output amplifier and present no additional loading
on the signal. Included into the design of the amplifier is the adjustment for phase of the bass
amplifier, thus ensuring that the system is in phase at the crossover point (impossible in a passive
system). Other features include momentary gain reduction circuits which prevent clipping by
rounding the waveform, these circuits protect the drive units from damage and will cause less
stress to the amplifier. Since these circuits are very fast they only introduce harmonic distortion at
the instant they operate, they are normally undetectable. Many users of conventional amplifiers
will be aware of amplifier clipping when playing at high levels. It is therefore relevant to note that
high levels of output are obtained without the audio cue of clipping.

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S Y S T E M O V E R V I E W

pin 1 → Screen
pin 2 → Signal+ (hot)
pin 3 → Signal – (return)

2

1

3

Signal Input 1
3 Pin XLR 2

3

PUSH

The P4 four – way monoblock has been developed for the most demanding studio
installation. It will release the full potential of an ATC monitor by providing an integrated solution to
amplification.
Incorporated into the P4 are all the necessary phase control, crossover and protection circuits
required to give accurate and lasting performance under the most demanding conditions.
Four amplifiers provide drive to two bass outputs, one midrange output and one H.F. output. A
total system output of 850watts RMS power is available. All amplifiers are class AB while the Mid
and H.F. amplifiers run at class A to high levels to provide a very clean dynamic performance. The
class A operation is accommodated by a large heatsink kept at a controlled temperature by three
low speed fans.
This fully integrated package has the major benefits of high power in a space saving and cost
effective package when compared with using individual amplifiers, crossover and protection
circuits.
Other features of the P4 include simple front panel indication and control, single locking four way
speaker connection, remote status output and control. System performance (includes the
monitors) is set at the factory allowing a plug and go setup.

C O N N E C T I O N S

Only three connections per monitor are required, one for main power, one for the input signal and
one speaker connector. The mains connection should only be made with the cable provided, this
cable meets the approved standard for the region to which the monitor is supplied. NOTE: The
mains connection Must Always be Earthed. The signal cable (not necessarily supplied) should
be of a good quality XLR balanced configuration (unbalanced configuration is explained later).
The XLR pin configuration is :

Ready made speaker cables are
supplied with the amplifier,
recommended length is up to
10mtrs and 5mtrs is supplied as
standard. If greater cable lengths
are required then the supplied
cable can be cut 500mm from the
connector and a larger 4mm2
cable can be spliced onto the
ends to increase the length, 4mm2
being sufficient width for up to
20mtrs.

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Speaker Connector
Type: CON-UN-06103

A:Bass 1+ G:Bass 1­B:Bass 2+ H:Bass 2­C:Mid+ F:Mid­D:HF+ E:HF-

G

A

B

C

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F

H

Speaker output

BALANCED CABLE
UNBALANCED CABLE

Speaker Connections are made via an 8-pin high capacity connector as shown above.

S I G N A L C A B L E O P T I O N S

The two figures below show the normal connections for a balanced and an unbalanced
configuration. A balanced XLR to XLR connection will have very few problems. With an
unbalanced XLR to Phono connection, it is possible that there may be problems with earth loops

causing hum. There are many
ways to eliminate this problem.
A good starting point is to
disconnect the screen from the
phono end. This may help on
pre-amps that are double
insulated (ie: have no earth).
OR disconnect the screen at the
monitor XLR. This will make the
pre-amp the reference for the
earthing

P L A C E M E N T

Perfection is not an option here, often the monitors will be installed in rooms which are
comfortable to sit and talk in. A mixture of carpets, curtains and soft furnishings will see to it that
middle and high frequencies are reasonably well controlled. There may however be low frequency
problems, either too much or too little bass. To avoid or minimise these effects the monitors
should be kept away from corners or walls – start with 1 metre from the side walls and 2 metres
from the back. All rooms vary and it is a good idea to experiment with both the listening and
speaker position until a good compromised is reached. For professional installations the
requirements are often very different. Please consult with an experienced acoustician.

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O P E R A T I O N

Standby

status/error

indication

normal

operation

when lit

push button

blue

tri-colour

Front Panel Controls

INSTALLATION

The P4 is designed to be free standing or rack mounted (using suitable shelving). Consideration
should always be taken to ensure adequate ventilation. The cooling of the amplifier is achieved by
forced ventilation at the rear of the amplifier with an exhaust vent at the front of the amplifier. DO
NOT obstruct either front or rear vents or enclose the amplifier.
When switching from standby to normal operation it is expected that you will hear a mild thump
from the amplifier as the main power transformer energises. If more than one amplifier is to be
connected to the same power outlet it is recommended that they are switched on in sequence –
important if switching by remote.

COOLING

The fans will only run when the heatsink temperature reaches approximately 30°C and they will
continue to run even in standby mode until the temperature has dropped to approximately 20°C.

CONTROLS

Control and operation of the P4 is simple once all connections have been made.
Mains power is isolated by a toggle switch on the rear of the amplifier and must be in the on
position to allow operation. To activate the amplifier press the standby button once, this will start
the power up sequence :-

1. Button pressed

2. Green LED turns to Orange

3. Blue LED starts flashing (protection circuit checks)

4. Orange turns Red (mute circuit released)

5. Red extinguishes

6. Blue LED stays constant (normal operation)

Failure to start will be indicated by a steady orange LED only, this state can be caused by a high
temperature or DC in one of the amplifiers, if neither of these conditions are true then a control
failure has happened and service is required.
During normal operation the Blue LED will remain lit. If the amplifier is being driven hard a RED
indication will show operation of the gain reduction circuits. Any other fault will cause the amplifier
to shutdown showing an orange indication with no blue LED.
If a fault has occurred the amplifier can be restarted by pressing the standby button, in the case of
an over-temperature the amplifier will have to be left to cool down before a restart.
The amplifier can be returned to standby be pressing the standby button, the blue LED will
extinguish and only a green LED will be displayed.

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C A R E A N D M A I N T E N A N C E

1 0 Volt
2 standby - control
3 pwd up - out
4 standby - out
5 error - out

1
2

3

4

5

Remote

High technology material finishes are used in this product. Surfaces are durable and
with a little care can be kept as good as new under conditions of heavy use. Normally a dry
duster will be all that is required to keep the finishes clean.
Heavy soiling can be remedied using an almost dry cloth that has been slightly moistened with a
non-abrasive household cleaner.
There are no components within the speaker that could be considered expendable, or that would
benefit from regular maintenance. There is no requirement for any kind of routine service work
and there is no schedule for preventative maintenance.
In the unfortunate event of any malfunction, as there are no user replaceable parts within the
speaker, repair should be referred to either the supplying dealer or consultant, the relevant
importer, or ATC. ATC has every confidence in the quality of each product that it manufactures;
please consult your local dealer or importer for applicable warranty terms.

R E M O T E O P E R A T I O N

Special facility for remote operation of the P4 is catered for by the inclusion of 5-pin DIN connector
on the rear panel. ATC does not supply a remote operation unit, but the connections required to
make use of this function are as follows:

 Pin 1 - acts as 0 Volts / logic ground
 Pin 2 - Standby / operate mode can be toggled by momentary grounding of pin 2.
 Pin 3 - will be at 5 Volts when the amplifier is in normal operating condition
 Pin 4 - will be at 5 Volts when the amplifier is in standby
 Pin 5 - will be at 5 Volts on any error including drive limit
 Pins 3,4 & 5 have a series resistance of 240R allowing sensing or drive of LED’s only.

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S P E C I F I C A T I O N S

OUTPUT POWER (RMS)

HF

MF

LF

100 WATTS INTO 6 OHMS

200 WATTS INTO 16 OHMS

275 WATTS X 2 INTO 8 OHMS

INPUT SENSITIVITY

1 VOLT

INPUT IMPEDANCE

10K OHMS

AMPLITUDE RESPONSE

5 HZ – 20 KHZ ± 0.1dB

SIGNAL / NOISE RATIO

BETTER THAN 105dB

CROSSTALK

BETTER THAN 90dB

POWER REQUIREMENTS

100, 115, 230 VOLTS @ 50/60 HZ (REGION DEPENDENT FACTORY SET)

POWER CONSUMPTION

150 VA (STANDBY MINIMUM), 1200 VA (MAXIMUM)

OVERLOAD PROTECTION

ACTIVE FET MOMENTARY GAIN REDUCTION

DIMENSIONS

OVERALL DEPTH

FRONT PANEL & HANDLES

REAR HANDLES

AMPLIFIER BODY

19 INCH RACK MOUNTABLE (5U HIGH)

545 MM

75 MM
40 MM

430 MM

OVERALL WEIGHT

40 KG (45 KG WHEN PACKED)

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