4
the amplifier to a qualified technician. The
Wiring diagrams for the changes are inside
of the unit.
Do not use fast blow fuses.
Amp Out
– The two ¼ inch jacks accept
the speaker connection cables. The jacks
are wired in parallel along with the NL-4
connector. The total speaker system
impedance should not exceed 4 ohms.
Effects Send/Return
– These standard ¼
jacks allow you to send and receive your
signal to and from external devices. The
effects loop is positioned post (behind) the
compressor and enhance control and prior
to the tone section.
Recording Out
– This fully balanced XLR
output allows you to send a post-EQ/pre-
master signal to a recording or sound
reinforcement mixing console. This output
is designed to allow use with phantom
powered systems. Pin 2 + signal.
D.I. Level
– Controls the level being sent
from the XLR balanced output jack.
Ground Lift Switch
– This switch lifts the
ground within the balanced output system to
allow you to eliminate excessive noise when
connected to external systems.
AUX In Right /Left -
These standard ¼
mono jacks are designed to accept the
stereo signal from an external source such
as a CD or cassette player, drum machine,
synth. module, etc. The stereo signal is
summed prior to the master volume control.
The signal enters the system post the tone
controls. These jacks can also be used to
return a studio cue signal, allowing the
WT-550 to provide you with your own
headphone mix in the studio.
Tuner Out Jack
– This standard ¼ inch
jack is designed to provide a post-tube, pre-
gain signal for connection to a tuner. It can
also be used to provide pre-tone signal to
other devices such as a direct box or
console.
Cooling System
/
Output Protection
–
Your amplifier features a thermostatically
controlled fan, which will switch on when the
internal temperature reaches 130 degrees F.
In low volume situations (into 8 Ohm loads)
the fan may not come on at all. The system
also features a high temperature thermal
safety system which will activate if the
operating temperature goes above 200
degrees F. This circuit will turn the system
down as needed in the event of overheating.
It will automatically operate at the best
possible level it can until the unit cools down
to a safe operating temperature. Usually it
takes from 2 to 5 minutes before the unit will
begin to operate normally again. (Note: the
D.I. will continue to operate normally even
when the amplifier is in thermal shut down
only the stage sound will be lost.):
AMPLIFIER:
The amplifier has full output
protection from short circuits and incorrect
loads. Unlike the older World Tour amplifiers
the 550 has a full fold back limiter system
that allows it to deliver what ever power it
can into any load rather than just shutting
down as the older models were designed to
do. As soon as the load condition is
corrected the unit will return to full power
immediately.
OPERATING INSTRUCTIONS
MECHANICAL AND THERMAL
ISSUES
– Your amplifier should always be
placed for operation away from sources of
moisture or heat. Care should be taken not
to obstruct the ventilation holes on the top
and sides of the unit. In the event of thermal
shutdown, you should eliminate the cause
of the thermal problem (poor ventilation,
speaker loads
lower than
2 Ohms
)
immediately. The supplied rack ears can be
used to install your amplifier in a
conventional equipment rack for protection
during transportation.
ELECTRICAL CONNECTION
– The WT-
550 requires at least 15 Amps of correctly
wired alternating current for proper
operations.
CONNECTIONS
– All line connections
(everything but the speakers) should be
made with high-quality shielded cables. The
use of speaker cables for line connections
will result in excess noise. Speaker
connections should be made with high-
