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QSA 300
ACTIVE SPEAKER
User Manual
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CONTENTS
QSA 300
Active Speakers
User Manual
Contents
Safety
Installation
Connections
Glossary
Operating Tips
Troubleshooting
Inputs & Outputs
Specications
Accessories
P.01
P.02
P.03
P.04
P.05
P.06
P.07
P.08
P.09
QSA 300
User Manual
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30
c
o
Safety Precautions
Flying and installation of this
speaker cabinet must be carried
out by suitably qualied personnel following the approved
safety standards.
Do not attempt to clean the
plastic enclosure with solvents
or petrochemical based cleaners.
The power voltages of the
ampliers inside these speakers
are high and could cause serious
injury or death if touched while
the power is connected. Do not
open the case as there are no
user serviceable parts inside.
Do not expose the speaker
cabinet to direct precipitation
or stand in water. Liquid getting
into the box will risk a short
circuit and will be hazardous.
Do not stack the speaker
cabinet in a manner that could
cause injury should a cabinet
become dislodged.
Do not place sources of heat
on the speaker cabinet such as
lighting equipment or smoke
machines.
Attention
Before connecting or operating your new
Quest Engineering speaker, please study
the accompanying instruction manual
paying particular attention to the operating
precautions and wiring procedure.
Quest Engineering will not assume responsibility for incorrect installation or operation of
this product.
Very important
Before using your speaker check to make
sure that the selection of the power supply
voltage (115/230 Volts) is set correctly for
your country. An incorrect setting can lead
to severe damage to your new powered
speaker on activation. If you are not certain
that it is set correctly, check with your Quest
Engineering dealer.
1
SAFETY
QSA 300
Active Speakers
User Manual
QSA 300
User Manual
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Description
The QSA speaker range is a two way active
bass reex design suitable for mobile or
installation use. The ampliers are a highly
efcient bi-polar split rail design capable
of high power yet are light in weight. There
are separate ampliers for the high and low
frequency drivers and both are protected
by high speed limiter circuits that monitor
peak and RMS power. The operation of
these devices will not affect audio quality
due to their advanced design. Limiters and
compressors are not a substitute for sensible
operation. The system will sound at its best
when mixers and other signal processors
in the audio chain are not being over driven
into distortion.
Full Range or
Mid-High Applications
The design characteristics make the QSA
series suitable for both full range use or as the
high-mid component of a multi way system
with sub-bass enhancement. Coupled with
the Quest Engineering QSA 900 compact
active sub-bass system they will provide high
performance multi way audio system.
Installation
Temporary installation is possible with the
35mm oor stand mounting in the base
of the enclosure. Foldback installation is
possible with the addition of the oor monitor
supplied. Optional metal monitor cradles are
available from your Quest Engineering dealer.
Flying Installation
Two M 8 thread inserts are located on the top
and one under the QSA series enclosures.
These are intended to be used with the designated “U” shaped bracket.
QSA Range Flying Accessories
QSA-FL 1 Wall bracket kit
QSA-FL 2 Wall bracket vertical pole mount kit
Safe Installation Procedures
(a) Under no circumstances attach the box
with less than two of the threaded inserts.
(b) The speaker box must not be installed in
a manner where the weight is not equally
distributed between two insert points.
(c) One pair of threaded inserts may only
carry the weight of one box. Therefore
multiple box rigging from one pair of insert
points should not be attempted.
(d) The carry handle is not intended to be
used as a ying point. Do not suspend
over peoples heads with the handle as a
ying point.
(e) Do not locate boxes near sources of
moisture or where water can enter the box.
INSTALLATION
2
(a)
(b)
(d)
(c)
(e)
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Active Speakers
User Manual
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User Manual
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1. Power supply input. Make sure that the
voltage selector is set for your Country’s
correct voltage.
2. Protection fuse. Use only fuses of the
correct Amp rating. If it blows more than
once, return the box to a Quest
Engineering service centre.
3. Power on/off switch.
4. Microphone level (low impedance) input.
5. Microphone balanced input volume control.
6. Microphone input overload indicator
7. Bass roll off for microphone input
8. Microphone input signal presence indicator
9. Line level balanced input.
(To mixer or other +4 dB or less line level)
10. Line level volume control.
11. Line level input overload indicator.
12. Line level signal presence indicator.
13. Line out. This is a “buffered” output at a
xed level.
14. Master volume.
15. Clip/limit indicator. If this LED illuminates
for more than an occasional ash, turn
down the mixer output. If you need more
volume, set up more speaker boxes.
16. Power amp active indicator.
CONNECTION
3
1
2
3
14
4
10
11
12
13
15
16
6
9
7
8
5
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Active Speakers
User Manual
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User Manual
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Compression: An electronic device that
reduces the dynamic range. In other words,
makes the loud parts of the music less loud
and the quiet parts appear louder. When used
correctly it can make live music sound more
even and balanced.
Limiter: An electronic device that will prevent
the signal from exceeding a set level of
output. Normally used as a system protection to prevent it from being over driven by
excessive input.
Phase (in or out of phase): This really means
speaker polarity. The input terminals of a
normal loudspeaker have a + positive red
terminal and a - negative black terminal.
In the case where there are two speakers
operating as a pair or together as an array,
will need to all be wired the same way. If a
speaker connecter, speaker lead or speaker
box is wired in reverse to a box near it, loss
of performance will result. This may be in the
form of lost low frequency response. In this
case you will see the bass speaker working
hard but as you move away from the box, the
bass frequencies will seem to “disappear”.
Check that your speaker leads do not have
one lead wired in reverse at one end and
that the speaker boxes are all wired correctly
internally. This can happen when a speaker
box has been repaired and then not assembled with the wiring connected correctly.
Input
Signal
Electronic
xover
Low Freq.
Amp
Low Freq.
Drive
Hi Freq.
Drive
Hi Freq.
Amp
Clipping
Clipping
GLOSSARY
4
Glossary
Basic professional audio practice
and hints for best results
Pre amplier: That part of the signal chain
where a signal from a microphone, turntable, CD player or other signal source is rst
amplied. This will normally be at the input of
a mixer and is necessary to boost the signal
enough to be then mixed and amplied by a
power amplier.
Power amplier: Boosts the signal enough
so it can be reproduced by a loudspeaker.
Electronic cross over: Splits up the full
range audio signal to separate high and
low frequencies. This is done to send low
frequencies to the bass speaker and high
frequencies to the tweeter or high frequency
horn driver.
Self powered: Refers to a speaker or a mixer
that contains a power amplier.
Clipping: Distortion that is caused by having
too much signal at an input causing the
amplier to overload. It is called clipping
because it will cause a smooth wave to be
cut off at the peak of the wave. In other
words, “clipped”
Gain structure: The relationship of input
levels to output levels in a signal chain. An
example of incorrect gain structure is when
a mixer is turned up to the point of audible
distortion (red lights ashing serious overload), and the power ampliers are turned
down and running at only 30% power.
Compressor
Threshold
Limiter
Threshold
1:1
3:1
Output Level
10
10
Output Level
10
10
1:1
0:1
QSA 300
Active Speakers
User Manual
QSA 300
User Manual
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Operating tips
To avoid overloading the pre amp inputs,
always operate the master volume at a high
level and control the volume from the input
volume. The ideal situation is to have all the
components of the audio chain operating at
the same operational range. Do not run the
system with the mixer “peaking in the red”
while the box is turned down.
Also do not operate the system with the input
peaking (red overload light on or ashing) and
the master volume turned down.
Red lights ashing on a mixer indicate
distortion. If you have a mixer with the facility
to show you the input level on a meter, for
example then you push a CUE/PFL button,
set the input level to below the level of the
red end of the LED ramp. If you run the row
of red lights to the end of the ramp you will
cause distortion at the very start of the pre
amplier stage of the mixer. At this point
it will sound dirty and “zzy” regardless of
how good the rest of your sound system is.
The rest of the system will be reproducing a
distorted sound. If you need more volume,
turn down the input signal so it is out of the
red and turn up the output of the mixer.
OPERATING TIPS
5
MIXER
MIXER
MIXER
AMP
AMP
AMP
QSA 300
Active Speakers
User Manual
QSA 300
User Manual
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1
1 2
5
10
1
5
100
5
CLIP/LIMIT
10
1
1 2
5
10
1
5
100
5
CLIP/LIMIT
10
1
1 2
5
10
1
5
100
5
CLIP/LIMIT
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TROUBLESHOOTING
6
Trouble shooting
Buzzes and noises in the sound system.
Getting rid of unwanted noises is a study in
itself. Most of the noise, (apart from undesirable program) will fall into three categories.
(A) White noise. This is the hiss that suggests
that the gain structure is set incorrectly.
Something in the signal chain is boosting too
much or an input is set too sensitive. If your
equipment has gain switches on it, set them
all the same. If the switch is labelled +4dB,
set them all to that gure. If one piece of
equipment seems to be overloading, set them
all to -10/-20dB and be prepared to boost
the input level of the QSA input. The last unit
in the chain should be set to +4 dB at the
output stage if possible when connected to
the line level input of the QSA series input.
(B) Low frequency hum. This is often
caused by noise from the power leads being
picked up by the audio signal cables. The
preferred solution is to connect up your
system with “balanced” XLR microphone
cables. Especially if you are running the
cables a long distance, (more than 5Mtrs
/15 Ft). The other solution is to make sure
that your audio cables are as far from power
cables as possible.
(C) Buzz. Sometimes you can experience
a hum and buzz together. A buzz is almost
always a problem with the “earthing” of the
system. It will often occur when you have the
system powered from sperate power outlets
in the same building or audio and lighting
sharing a common power circuit. Even when
the audio and lighting systems are powered
from separate sources, there can still be a
common earth between them. For example,
a smoke machine may be powered from the
lighting system, yet the trigger mechanism
could be connected to the audio system
through the audio multi-core/snake. An earth
connection between the audio and lighting
will now exist and a buzz could be amplied
in the audio system. The simple solution is to
power your audio circuit and everything connected to it from the same source. If the buzz
persists, check your signal cables, one may
have an earth/shield disconnected.
A cheap but possibly life saving investment
is a domestic power tester to check that the
power supply sockets are correctly wired.
Faulty or incorrectly wired power is a booby
trap that is more common than you think.
It is wise to avoid switching on or off devices
in the signal path while the speaker system
is powered and turned up. Otherwise loud
clicks and bangs could result. When shutting
down the system, always turn the speakers off rst. This is to prevent the speaker
amplifying the sound of the other equipment
in the chain being shut down. The reverse is
true when powering up. Mixers and effects
on rst, power ampliers or powered speakers on last.
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Active Speakers
User Manual
QSA 300
User Manual
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INPUTS/OUTPUTS
7
Inputs and outputs
The inputs can accept both XLR and phono
connectors. If you are connecting multiple
boxes together is unprofessional practice to
use a mixture of both phono and XLR types
of leads. Use one or the other otherwise an
out of phase situation can result.
Tips on “ying clusters”
When very high output or broad coverage is
required, it is common practice to assemble
an array of speakers together.
In a own horizontal array of high/mid congured speakers, best results are obtained
by angling the boxes apart slightly at the
front of the array while the rear of the boxes
must be together on the same vertical plane.
The purpose is to minimise phase shift and
interference effects between the boxes. If
two boxes are directing acoustic energy into
the same coverage area, loss of smooth
frequency response will result. This is called
“lobing” as “ngers” of both frequency peaks
and dips spread out across the coverage
area, especially at the area where the signal
from the overlapping coverage converges.
QSA 300
Active Speakers
User Manual
QSA 300
User Manual
QSA 300 Gig Array
Page 10
SPECIFICATIONS
8
Quest Engineering QSA 300 Specications*
Type
Loudspeakers
Angle of Coverage
Maximum SPL
Processor section
Crossover frequency
Loudspeaker protection
Amplier section
Type
Low frequency
High frequency
Distortion
Input
Output
LED Indicators
Controls
Power Supply
Cabinet
Flying Points
Dimensions
Packing Dimensions
Net Weight
Shipping Weight
Self contained bi-amplied bass reex
1 diameter 300mm (12”) woofer
High powered 80mm (3”) voice coil
Titanium diaphragm
90 X 60 degrees
123 dB (Nominal)
127 dB (Peak)
1800 Hz (24dB/oct)
Thermal - over excursion - multi band input limiting
Fully discrete bi-polar split rail high efciency design
Nominal 240W
Music power 450W
Nominal 60W
Music power 110W
Less than 0.1% 1K-10K - nominal power
XLR-Phono balanced MICRO level -30dB volume pot
(80 Hz roll off switch)
XLR-Phono balanced LINE level +4 Volume pot
XLR xed line level electronically buffered
Signal presence Micro/Line - Input overload Micro/Line
- Power amplier - Clip/Limit
Microphone - Line - Master volume - Low frequency roll off
115/230 Vac (+ 7%) - 50/60 Hz / 400VA
4 x M8 on top, bottom and rear sides.
450 x 360 x 690 mm
505 x 410 x 755 mm
23 Kg (57 lbs)
27 Kg (62 lbs)
QSA 300
Active Speakers
User Manual
QSA 300
User Manual
* Quest Engineering reserves the right
to make changes in specications, or
products without prior notice.
Page 11
ACCESSORIES
9
Accessories
Accessories
QB350
QSSAL
Protective nylon padded speaker bag
Heavy duty aluminium speaker stand with carry bag
QSA 300
Active Speakers
User Manual
QSA 300
User Manual
Page 12
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