| PA Equipment Knowledge Base
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CONNECTORS
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There are various connectors used with our range of PA amplifiers.
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A popular audio connector used on auxiliary inputs & booster in/out connections, also commonly used on mixers, CD & tape players. They are wired using single core screened cable
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These are the industry standard microphone connectors, robust and relatively simple to install. There are a number of ways in which they can be wired.
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(i) BALANCED operation
Pin 1 connects to screen (Signal earth)
Pin 2 connects to signal + (Live)
Pin 3 connects to signal - (Return) |
(ii) UNBALANCED operation
Pins 1 & 3 connect to the screen of the cable
Pin 2 connects to signal conductor. |
The PIN numbers are identified on the XLR plug and an easy way to remember how they should be wired is:
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X = Earth (Pin 1)
L = Live (Pin 2)
R = Return (Pin 3) |
| An unbalanced microphone can only be used up to a maximum of 10 meters away from the amplifier. Any more than this and noise problems become apparent.
A balanced microphone will allow cable runs of up to 100m without any loss of performance.
For unbalanced operation, a single core screened microphone cable can be used, but for a balanced line a twin core screened cable is required.
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3. 6.3mm (1/4”) Jack plug. |
There are two versions of this connector in common use, MONO & STEREO. The stereo plug is used for balanced operation and wired as follows: |
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TIP - Signal +
RING - Signal -
SLEEVE - Screen |
For unbalanced operation the RING & SLEEVE should be joined.
The MONO version can only be wired unbalanced as follows :
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TIP - Signal +
SLEEVE - Screen
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4. DIN Plugs |
These are mainly used for microphone priority access on some of the Adastra amplifiers and as there are a number of different ways they can be wired for various functions, it is best to refer to the installation guide for specific models.
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LOUDSPEAKER CABLE SIZES & CONNECTIONS. |
100V LINE |
When installing a 100V line system, it is important that the correct size of cable is used to connect the speakers to the amplifier. The following chart gives an indication of what should be used: |
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As the voltage on the line can approach 100 volts, installation must
follow best practice with double insulated cable being used . Cable runs
should be kept away from any potential source of interference such as 3
phase mains, data, telecom cables etc.
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100V Line Systems must always be wired in PARALLEL :
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NOTE: The total load presented to the amplifier must not exceed the
rated output of the amplifier or damage can result.
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LOW IMPEDANCE |
Some amplifiers in the Adastra range have the facility for connection of
low impedance loudspeakers. Low impedance installations require heavy
cable feeding the loudspeakers to minimise losses and short cable runs
are recommended. Where it is intended to use multiple low impedance
speakers to cover an area, the speakers must be wired in a series/parallel
arrangement in such a way as to present the correct load to the amplifier. |
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NOTE: The total load impedance presented to the amplifier must never
be below the rated amplifier impedance , otherwise damage can
result. To avoid damage to the speakers the total wattage of the
driver units should be at least 30% higher than the rated power
output of the amplifier. |
You must NEVER mix 100V line and low impedance
speakers on the same system. |
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Horn speakers are typically used in noisy environments , outdoors or
areas that are quite large in size. The main disadvantage with this type
of speakers they cannot reproduce music at all. |
100V Line Volume Controls |
These controls are specially designed for 100V line operation and simply
wired in – line ( in series) between the speaker and the amplifier. The
maximum wattage rating of the volume control must be observed and
not exceeded, otherwise damage to both control and amplifier can
occur.
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GENERAL INSTALLATION CONSIDERATIONS |
DO NOT run microphone cables near mains, data, telephone or 100V line cables.
DO NOT run 100V line cables near data, telephone or other low voltage cables.
DO NOT exceed 90% of the amplifiers output power when using 100V line (speech only).
DO NOT exceed 70% of the amplifiers output power when using 100V line (high level background music).
DO NOT use re-entrant horn loudspeakers for background music unless the loudspeaker has been specifically designed for this purpose.
AVOID Jointing the microphone cable, when this is unavoidable make sure a good screened connector is used, e.g. XLR.
ALWAYS use a balanced or floating low impedance microphone terminating into a balanced input on long microphone cable runs.
ENSURE that all loudspeakers are in-phase.
ENSURE that there are no short circuits on the loudspeaker line before connection to the amplifier. |
Connectors
