PC80 MKII Phase Checker
User Guide
LA Audio (an SCV International Group Company),
40 Chigwell Lane, Lughton, Essex, IG10 3NY, UK
Tel: +44 (0)208 418 0778 Fax: +44 (0)208 418 0624.
email: [email protected]
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1. INTRODUCTION
The PC80 is an advanced measuring system which allows an engineer to check the phase
accuracy of any electronic audio system. It is ideal for the toolbox being small, light and battery
powered.
The system is made up of two hand held units. The emitter (PC80E) generates a wide band 1Hz
pulse as an output signal on an XLR connector or through its own built in speaker, this signal is
then passed through the signal chain under test and fed into the receiver (PC80R), electrically via
its XLR connector or acoustically by the internal microphone. Indication is then given as to whether
the received signal is in or out of phase.
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2.SPECIFICATIONS
GENERATOR
Pulse rate
1Hz
Frequency spectrum, electrical
Frequency spectrum, acoustic
Output level, electrical
(Acoustic level is fixed)
Output load impedance
Output source impedance
Power
1Hz to 20KHz
200Hz to 5KHz
0 to 1V
!K Ohm to infinity
1K Ohm
9V PP3 battery
(= approx 50 hours)
10mA
Power drain
RECEIVER
Frequency spectrum, electrical
Frequency spectrum, acoustic
Input impedance (Mic)
Input impedance (Line)
Input level (Mic)
1Hz to 20KHz
10Hz to 1KHz
1K Ohm
10K Ohm
10mV - 1V
0.5V to 50V
0V to 1V
Input level (Line)
Output level
Power
9V PP3 battery
(= approx 50 hours)
10mA
Power drain
PHYSICAL CHARACTERISTICS (each box)
Dimensions
Weight
113mm W x 60mm D x 31mm H
0.25 Kg
Shipping weight
Operating temperature
Storage temperature
0.65 Kg
0 - 50 deg C
-30 - +75 deg C
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3. INSTALLATION
INSPECTION & UNPACKING
The PC80 is carefully packed at the factory in a carton designed to withstand transit handling,
however, if transit damage is evident, DO NOT discard any of the packaging and notify the carrier
immediately, it is they who are responsible for any claims.
OPERATING ENVIRONMENT
The units are designed to operate between 0 and 50 deg C (32-122 F) and in an atmosphere of
relative humidity up to 80%.
POWER REQUIREMENTS
Each unit is powered by a 9V PP3 battery which is fitted by removing the rear cover of the box (4
screws) and plugging the battery into the connector provided.
EXTERNAL CONNECTIONS
Generator:
Receiver:
Output male XLR type
Input female XLR type
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4. OPERATING INSTRUCTIONS
The generator provides special pulses which may be fed to the audio system to be tested either by the in-
built speaker or via the output connector, the level of this may be adjusted by the level control. The speaker
output level is fixed.
Once this signal has been fed through the system under test, the receiver will be able to indicate whether the
received signal is in phase or out of phase, the appropriate LED (IN-PHASE or REVERSE) will flash at the
speed of the pulse. The signal may be fed into the receiver by one of three methods, this is determined by
the INPUT-MODE switch.
•
•
•
Selecting INT uses the built in microphone.
Selecting EXT allows an external microphone to be used.
Selecting LINE allows a line level signal to be used.
Note: The unit does not provide phantom power for a microphone input.
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5. APPLICATION NOTES
•
•
Feed the signal from the generator into a public address system and place the receiver in front of each
loudspeaker in turn to ensure that the system is in-phase.
For a multi-mic application. Connect the receiver to a mixing console output and feed each microphone
with the generated pulse. The receiver may then be used to check that all the mics are in phase, (if out
of phase, cancellation effects may occur where mics are close together).
•
The system may be used for checking phase transmission on tape recorders, (be prepared for some
surprises!). This test can be made by recording the generated signal onto tape and connecting the
receiver to the machines output. This is really useful in the recording studio, when using effects off tape
which are combined and for checking tape machine wiring.
•
The system may also be used to check telephone lines, satellite links etc.
Notes:
It is important to note that the PC80 measures absolute phase.
Care should be taken when using the PC80 because some crossover networks and speaker systems
deliberately place certain speakers out of phase for correct operation.
Check the technical specifications of the system before commencing the test.
The system is not affected by any propogation delay or time delay effects.
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6. CABLE TESTING
The PC80 is designed to be an overall polarity checker of electronic audio systems, not a cable tester.
If a false reading is found in a system and a cable fault is suspected then ideally a cable tester should be
used to trace the fault. The LA Audio 'T-Box' will check a cable and indicate which pin is o/c or which wires
are swapped. However, if you want to check an individual XLR cable and the PC80 is what you have at
hand:
•
•
Set the 'Hot Pin' switch on both units to Pin 2 and select 'LINE' as the input on the Receiver.
Set the 'Hot Pin' switch on both units to Pin 3.
If the cable is correct the 'Green' LED will flash in both cases, if the cable is reversed it will show nothing,
thus indicating a fault condition.
Note: The Level potentiometer on the Emmiter should be set to approximately 3 o'clock for this test.
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