BSS Audio AR 130 User manual

BSS AUDIO
AR 130 PHASE CHECK SYSTEM
IMPORTANT - On receipt of these units, check for visible damage. Any claims for transit
damage must be made within 14 days of receipt to be covered by warranty. It is important
that all repairs are carried out by an authorised BSS agent, as evidence of internal
tampering may invalidate this warranty.
TO OBTAIN THE BEST POSSIBLE RESULTS, THIS MANUAL MUST BE READ PRIOR
TO USE.
INTRODUCTION
The AR130 test system is a specialist piece of equipment for checking the phase
correctness between input and output of most electrical, electronic or electro-mechanical
units. This unit must have at least one two-wire port, which need not be balanced. Such
examples are multiway connecting cables, equipment racks, sound mixing consoles,
microphones and loudspeakers.
The test system consists of a SOURCE, the AR13OS, and a DETECTOR, the AR130D.
The source provides an encoded test tone, and is normally connected to the equipment
input. The detector dictates the phase, either in or out, between input and output, and is
connected to the output of this equipment. For units which are frequency dependant,
provision is made to adjust the test tone frequency. Also available is a foam lined carrying
case to house the phase check set, two XLR balanced to unbalanced converters and two
spare batteries.
1.0 GENERAL
1.1 Batteries
Ensure unit is switched off before fitting two 9 volt, PP3 sized batteries, and check carefully
for correct orientation. It is strongly recommended that alkaline type cells are used, as
these will give extended life, and also provide enough power for the AR130S to drive an 8
ohm loudspeaker directly. On switching on the source, the range LED will illuminate, and
the step switch will allow selection of the frequency range. For the detector, only the ON
LED will illuminate. If the battery low LED illuminates check both batteries and their
connections.
1.2 Checking Operation
It is possible to check the correct operation of the system by connecting the source and
detector directly together with a standard balanced lead. The detector's green phase LED
will illuminate when the source output switch in the N position, and the red one when this
switch in the R position. This action can also be checked on all four frequency ranges, and
a range of source output level.
1.3 Connection
AR130: Before connection to your equipment, check the connector wiring diagram for
compatibility. If used on an unbalanced system, the supplied XLR converter can be used to
provide the necessary rewiring. AR130D: this has a universal input wiring configuration,
enabling all forms of wiring to be accommodated for without the need to use converters.
www.audiovias.com

1.4 Operational Procedure
After switching on the units, allow one minute before the taking of readings on the detector,
as the internal circuitry must be allowed to stabilise before correct results will be indicated.
When testing any type of equipment, always check for system operation by operating the
phase reverse switch on the source. A corresponding reversal will be indicated by the
phase LED's on the detector. This will serve as a check that the system is functioning
correctly.
1.5 Signal Levels
Always ensure the source's output level is sensible for the equipment under test, and does
not cause overloading. Excessive hum or noise may cause indeterminate results, with
detector LED's alternately lighting.
1.6 Source Frequency
This must be set appropriately for the equipment under test, especially where it may have
frequency dependant parts and contain major phase shifts. Refer to the following sections
for specific details. When supplied, the frequency ranges will have been set to LOW =
110hz;
M1 = 500Hz; M2 = 3k5Hz; H = 10kHz.
2.0 APPLICATIONS
2.1 Passive Components
This includes connecting cables, transformers, line attenuators, etc. Connect the source to
the input, and the detector to the output, observing all the points as in section one above.
The source output level switch can be at OdB, and the tone frequency set to band Ration
M1. High ratio transformers should be tested in a step-down mode.
2.2 General Equipment
This includes all forms of signal processing units. Those containing filters or other
frequency/phase changing parts, should have their cancel or bypass switches operated.
Connect the source to the input, and the detector to the output, observing all points as in
section one above. The source output level should be set to suit the particular unit, to avoid
any overload within it. The detector has a wide dynamic range for its input level and will
accept anything from a few millivolts, up to fifty volts. For all wide-band equipment, the
source tone frequency can be set to either range M1 or M2.
2.3 Microphones
For phantom powered types, a separate powering unit will be required. For high impedance
moving coil types, a step-down transformer will be required. Connect the source to a
loudspeaker, either directly or via a power amplifier, and adjust to give a comfortable
listening level. The tone frequency can be set to either range M1 or M2. Connect a
microphone with a known phase wiring to the detector, and hold up to the loudspeaker, on
axis, and observe the phase LED colour. Repeat with the unknown microphone, and
compare phase LED colour with that of the known reference. For some microphones it
might be necessary to adjust the tone frequency to avoid a particular peak or dip in the
phase response.
www.audiovias.com

2.4 Loudspeakers
2.41 Consistency of phase between drivers of the same type, and operating over
the same frequency band.
Connect the source to the drive unit, either directly (if ambient noise is low), or via a power
amplifier and a uni-directional microphone to the detector. Set the source frequency range
to suit the particular driver, and hold the microphone up to the driver, on axis, and observe
the detector's phase LED. It will be necessary to select the required frequency by
experimentation, and adjusting via the recessed pre-set adjusters. Any frequency will do
that gives a good strong indication, and which is generally uncritical of microphone distance
or placement. Correct frequency choice is necessary due to the considerable phase
movement that occurs within loudspeakers and their cabinets. A hesitating detector
indication will generally indicate an incorrect choice of frequency. Avoid picking up reflected
sound from the sides of the cabinet horn flares, or room reflections, as these will be of
reverse phase as a consequence of their reflection, and will be added to the direct signal by
the microphone.
Having obtained a phase LED colour for this driver or cabinet, other units of the same type
can then be checked quickly for their consistency. Changing to other types of drive units will
probably necessitate a change in tone frequency. It will be observed that for a given drive
unit, the phase relationship between the electrical input signal, and the acoustical output, as
measured by the microphone, will change the frequency. This is quite normal, and indicates
the quite considerable phase movement within a drive unit and its cabinet.
In general the colour of the phase LED is unimportant, as long as all drive units and cabinets
of the same type, give the same result, when tested in the same manner. On cabinets with
more than one drive unit fitted, the detector will pick out reverse wired, or non working units.
Note that a reverse phase indication for one unit, which is mounted within the same
acoustical chamber as the rest, can mean that it is not working rather than the reverse
wired, as the cone of this unit will be driven by the back pressure generated within the rear
chamber by the other working unit.
2.42 Correct phase alignment at the crossover points
It is of prime importance in multiple speaker systems, where different drive units handle
different parts of the frequency spectrum, that at the crossover region, both drive units are
working acoustically together. This can be checked by setting the source tone frequency to
this crossover point, and then driving each unit, in turn, to give the same phase LED colour.
During this type of test, only the drive unit being measured should be switched on, otherwise
interaction can occur between the two units. It is also important that any crossover or phase
correction units normally used to drive the system should be incorporated within the test
system, as these are sometimes trimmed to suit the speaker at its critical crossover region.
BSS Audio
Linkside House,
Summit Road,
Potters Bar,
Herts EN6 3JB
England
Tel [phone]
Fax [phone]
WWW http://www.bss.co.uk
www.audiovias.com

www.audiovias.com