Ashly MA-500.8 Manual de instrucciones - Página 5
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MA Amplifier • Operating Manual
originate at the same AC power distribution
point. Do not lift or remove the amplifier power
cord earth ground pin.
2.2
Input Signal Wire
Use shielded wiring
for balanced or
unbalanced audio
signals. Shielding
which is properly
grounded will protect
the signal from outside
electrical interference
such as RF,
fluorescent lighting,
and computer/
display emissions.
Unbalanced or single-
ended (tip-sleeve)
lines of less than 10
feet are generally
ok, but for greater
distance or noisy field
environments, use
balanced input signal wiring.
Ashly recommends a stripped wire length
of 5mm (0.2 in) for use with Euroblock
connectors.
Note: If using an unbalanced input, connect
the signal wire to the (+)input pin, connect the
shield wire to the (-) input pin, optionally use a
piece of wire to link between the (-) input pin
and the G pin.
Avoid running low level signal wires in close
proximity or parallel to long speaker cables, AC
power cables, or power transformers, as they
can induce hum or oscillation.
2.3
Speaker Wire
Note: The sound system installer is responsible
for using loudspeaker wiring that is in
compliance with local electrical code. The
following recommendations for speaker
wiring are based on US National Electrical
Code Article 725. These are only guidelines,
consult your local code for specific up to date
requirements.
•
Class 2 wiring is typically used when the
maximum measured open-circuit speaker
output voltage is less than 120V rms.
•
Class 3 wiring is typically used if the
measured open circuit output voltage
exceeds 120V rms, such as when
amplifiers are used in bridged mode.
See the
specifications
for specific model
configurations that may require Class 3
speaker wiring.
Speaker wire gauge: MA amplifiers are capable
of delivering high levels of output current, so
the wire gauge used for speaker outputs is
important. Inadequate wire gauge, especially
over long distance, adds significant resistance
to the speaker's own impedance, reducing
the power which is actually delivered to the
speaker. It could also result in a decreased
damping factor and potential fire hazard. Since
power at the speaker load is of primary concern
in system design, refer to the table below to
best determine appropriate wire gauge for your
application.
The following table lists the resistance per 100
feet of common copper wire gauges, and also
lists the percentage of the speaker load power
which would be lost as heat in an arbitrary
100 ft run of different gauges of 2-conductor
copper speaker wire.
Wire
Ohms
8Ω
4Ω
Gauge
/100ft
load
load
#8
0.0605Ω
0.8%
1.5%
#10
0.1018Ω
1.3%
2.5%
#12
0.1619Ω
2.0%
4.0%
#14
0.2575Ω
3.2%
6.4%
#16
0.4094Ω
5.1% 10.2% 20.4%
#18
0.6510Ω
8.1% 16.3% 32.6%
This table expresses the power loss as a
percentage of the load's power rather than
the total amplifier output power in order to
accurately determine power loss at other cable
lengths. For example, if you plan to deliver 150
watts to an 8 Ohm load through 50 ft of 14 ga.
cable, the power loss in the cable would be
half that of a 100 ft run of #14 wire as shown
in the table, or 1.6% of 150W, which is an
insignificant 2.4 watts. However, if you were
to run 200 ft of 18 ga. cable to a 2 Ohm load,
the loss would be twice that of the 100 ft run
shown in the table, or 65.2% of 250W, which is
163 watts lost as heat. Always be sure to use
adequate gauge speaker wire.
2.4
Remote Control Wire
•
Remote DC level control - Bell or telephone
wire is sufficient for DC level control, as well as
CAT5 cable. The V+ and Ground pins from one
amplifier channel can be shared with other
remote DC level controls wired to the same
amplifier, however do not connect remote
control ground to any external grounds.
•
Remote Standby - This is a logic level
signal, use low gauge wire, shielding is
unnecessary.
2Ω
load
3%
5%
8%
12.8%
5