Installation Procedure - Quest Engineering QA 1004 User Manual

QA SERIES
User Manual

Installation Procedure

Mains Power Connection
Before connecting the amplifier to the mains power,
make certain that the voltage corresponds with that
indicated on the rear of the amplifier. A variation of
10% is acceptable. Refer to safety warnings before
switching on.
Power Up
It is standard procedure to power up the amplifiers last
and shut down first. The QA series amplifiers feature
turn on delays as the power up diagnostic circuits
search for faults, so turn on "thump" is avoided. The
speaker outputs are switched into circuit once checks
are complete and normal operating voltages are
present at all stages of the amplifier.
When powering up multiple amplifiers, a staged turn
on is suggested as the power surge of simultaneously
switching on multiple amplifiers can exceed the power
8
supply capability causing circuit breakers to disengage.
Power Requirements
The QA Series amplifier is capable of high output
voltages. When multiple amplifiers will be operating
simultaneously, make sure the power supply is
adequate for all amplifiers to draw full power. In this
case three phase power of sufficient Amperage supply
capacity will give best results from your amplifiers.
In the case where power is to be supplied from mobile
generators, It may help to "load the generator" with
some lighting to create a reserve of power from
the generator for the amplifiers. Amplifiers do not
necessarily draw high continuous power as lighting
will, but have a high demand for dynamic power
and can draw very high amounts of current for short
durations. If the power in not available, distortion and
reduced performance will result.
Rack mount installation
In permanent installation or mobile rack mounting it
is recommended to secure the amplifier from both
front and rear rack mounting facilities. For mobile
application, this practice is absolutely essential.
Damage to the amplifier caused by incorrect rack
mount installation or transit damage is not covered by
the warrantee.
Installation and electrical interference
Avoid installing your amplifier near sources of magnetic
fields such as radio transmitters, welding equipment,
User Manual QA Series
Power Amplifiers
high current transformers, lighting dimmers or electric
motors.
All signal cables should be physically isolated from
power cables and all audio and amplifier power should
be supplied via a circuit separate from lighting or stage
machinery power. Failure to observe this standard
may generate unwanted noises and hum to the audio
system.
Connecting cables
When connecting the audio system, use only balanced
three conductor signal cable of high quality (screen
pin1 plus two signal carriers pin2/3). Low cost cable is
more inclined to pick up radio frequencies and noise
under certain conditions. For speaker cabinets, always
use two core copper high current cables of suitable
length. The thicker the copper core, the less the loss
on a long speaker line.
It follows to not make speaker cable runs longer than
necessary. Long runs of thin cable will greatly reduce
the excellent damping factor of the QA series amplifiers
causing a loss of "punch" in the bass response. The
rule of thumb is to use as thick a copper core as is
practical. It is impossible for a cable to have too much
copper but too little will cause losses of power and
reduced damping factor. Unnecessarily long speaker
cable runs will have the same effect, especially when
left in a tight coil from a high powered amplifier.
1. BALANCED
GND
1
-
3
+
2
F ROM
I N P U T P RE A MP L IF IER
+
-
SHIELD
1. Balanced input connector wiring.
2. Unalanced input connector wiring.
Bridge mono operation
In Bridge mono mode, the output of channel A input
buffer amplifier is connected to both channel A and
channel B power amplifiers. The signal is routed in a
manner to bring the channels onto opposite polarity to
2. UNBALANCED
1
SHIELD
3
2
+
F ROM
I N P U T
P RE A MP L IFIE R
+
SHIELD