LA Audio Electronic Stereo System PC80 MKII User Manual

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.  
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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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