Input Wiring; Speaker Wire - Ashly CA Series Operating Manual

CA Amplifier • Operating Manual
powered up. The model number and power
consumption are indicated on the back panel
label placed near the AC inlet. To reduce the
risk of ground loop hum, all sound system
ground references should originate at the
same AC power distribution point. Do not lift or
remove the amplifier power cord 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.
Each channel's Euroblock, 1/4" phone jack,
and XLR inputs are wired in parallel, with
XLR pin 2 (+) and pin 3 (-). When using an
unbalanced input, wire the signal to the input
(+) Euroblock pin, phone jack tip, or XLR pin 2,
and also be sure to wire the input (-) pin, phone
jack ring, or XLR pin 3 to ground. Do not leave
the (-) input unconnected. 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 UL 60065 section 5.2-d and the
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: CA 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.
2Ω
load
3%
5%
8%
12.8%
5