OPERATING MANUAL
Q U A D
AMPLIFIER
QD-4240/4480
11
UNPACKING AND INSTALLATION
Although it is neither complicated to install nor difficult to operate your power Amplifier, a few minutes of your
time is required to read this manual for a properly wired installation and becoming familiar with its many features
and how to use them. Please take a great care in unpacking your set and do not discard the carton and other
packing necessary to return your set for when moving your set and are required if it ever becomes necessary to
return your set for service. Never place the unit near radiators, in front of heating vents, to direct sun light, in
excessive humid or dusty location to avoid early damage and for your years of quality use. Connect your
complementary components as illustrated in the following page.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK.
DO NOT REMOVE COVER (OR BACK).
NO USER-SERVICEABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
WARNING
To prevent fire or shock hazard, do not
expose the unit to rain or moisture.
This symbol is intended to alert the user to the
presence of uninsulated “dangerous voltage” within
the product’s enclosure that may be of sufficient
magnitude to constitute a risk of electric shock to
persons.
This symbol is intended to alert the user to the
presence of important operation and maintenance
(servicing) instructions in the literature accompanying
the appliance.
Caution: To prevent electric shock do not use this (polarized) plug with
an extension cord, receptacle or other outlet unless the blades
can be fully inserted to prevent blade exposure.
Attentions: Pour prévenir les chocs électriques ne pas utiliser cette fiche
polarisée avec un prolongateur, une prise de courant on une
autre sortie de courant, sauf si les lames peuvent étre
insérées à fond sans en laisser aucune partie à découvert.
FEATURES
• 4 CHANNEL AMPLIFIER
These quad amplifier has 4CH Amplifier circuit in the one unit.
• SUBSTANTIAL PROTECTION CIRCUITARY
To insure stability and reliability against over current and overheating extra protection circuitary is provided. In
addition, turn on delay and DC detection circuitary is provided to protect the loud-speaker.
• BRIDGED MONO FUNCTION
These quad amplifiers can be used for monoral powerful sound by selecting the mode switch.
• VARIOUS DISPLAY
To confirm the operating status, LED displays of protection, clip, and signals are provided on front panel.
• COMPACT SIZE
For valuable saving in rack space and slim exterior view, these amplifier is designed within compact size.
22
APPLICATION
• Home theater/multimedia
• Surround Sound-play back or Mix
• Stereo system with subwoofer
• Distributed sound installations
33
POWER
CHANNEL1
CHANNEL2
CLIP
SIG
PROT
SIG
CLIP
PROT
CHANNEL3
CHANNEL4
SIG
CLIP
PROT
SIG
CLIP
PROT
QUAD AMPLIFIE
4480
QD
121315171922295400012345678910111213151719222954000123456789101112131517192229540001234567891011121315171922295400012345678910
11
FRONT PANEL CONTROLS
326 4 3 2 64
1
55
1. POWER SWITCH AND INDICATOR
Lights whenever the QD-4240/4480 is powered on use this to power the QD-4240/4480 on or off.
2. PROTECTION INDICA T OR
This red LED indicator lights up for approximately six seconds when the amplifier is powered ON, indicating
that the soft-start protection system is working. No sound is output during soft-start up. If one of the
protection systems is activated during normal use, this indicator lights up and no sound is output. The
speaker system is actually disconnected from the amplifier outputs when this indicator lights up. The
protection systems are activated when overheating occurs or a DC voltage is present at the amplifier outputs.
If the problem is corrected, the protection systems deactivate automatically, this indicator goes out, and
normal amplifier operation is resumed.
3. CLIP INDICA T ORS
CLIP indicator on each channel illuminates when distortion reaches or exceeds approximately 0.5%,
indicating that the amplifier is being driven by excessively high inputs.
4. SIGNAL INDICA T ORS
These green LED indicators light up when the channel’s output signal exceeds 2Vrms (=
1 watt into 4 ohm).
5. INPUT A TTENUATORS
These are 21-step detented input signal attenuators. Attenuation range is from
6. HANDLES
You can handle this amplifier easily by using these handles.
1
/
2 watt into 8 ohm or
∞ to infinity (0).
REAR PANEL CONTROLS
~AC INPUT
230V,50Hz 420W
S/N
QUAD AMPLIFIER
MODEL NO : QD-4480
MADE IN KOREA
CH 1
CH 4
CH 3
STEREO
BRIDGED
PARALLEL
: BRIDGED:240W(8Ω)X2
OUTPUT POWER : STEREO:120W(4Ω)X4
STEREO
BRIDGED
PARALLEL
OUTPUT
INPUT
OUTPUT
INPUT
CH 1(4Ω~8Ω )
CH 2(4Ω~8Ω )
BRIDGE
(8~16Ω)
CH 3(4Ω~8Ω )
CH 4(4Ω~8Ω )
BRIDGE
(8~16Ω)
CAUTION;
TO REDUCE THE RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS
INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
AVIS;
RISQUE DE CHOC ELECTRIOUE NE PAS OUVRIR.
CH 1
CH 1
CH 3
CH 2
CH 4
BRIDGED MONO USE
CHANNEL 2, 4 CONTROL
IS "O" POSITION, ONLY
CHANNEL 1 AND 3
CONTROL ADJUSTS GAIN
PUSH
PUSH
CH 2
CH 1
PUSH
PUSH
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
213
HOT
GROUND
COLD
COLD
GROUND
HOT
PUSH
213
HOT
GROUND
COLD
44
4
11 3
2
1. INPUT TERMINALS (CHANNEL 1, 2, 3, 4)
Input connectors are provided both balanced combination jacks. Channel 1 input terminal is used in Bridge
mode and parallel mode.
• XLR-TYPE CONNECTOR
They are wired pin 1-ground, pin 2-hot (+), and pin 3 cold (–).
XLR MALE
COMBINATION
FOR INPUT
• PHONE JACK
They are wired tip-hot (+), ring-cold (–), and sleeve-ground.
2. MODE SELECTOR
Bridged mono or parallel operation are easily accessed by the slide switch. The input is applied channel one
only the corresponding front panel control is used to set the level, please refer bridged mono operation or
parallel operation.
55
CH 3(4Ω~8Ω)
CH 4(4Ω~8Ω)
BRIDGE
(8~16Ω)
CH 1(4Ω~8Ω)
CH 2(4Ω~8Ω)
BRIDGE
(8~16Ω)
CH 1(4Ω~8Ω)
CH 2(4Ω~8Ω)
BRIDGE
(8~16Ω)
CH 3(4Ω~8Ω)
CH 4(4Ω~8Ω)
BRIDGE
(8~16Ω)
3. OUTPUT TERMINALS
Output terminals are dual five-way binding posts and speaker connectors. Do not parallel the two outputs of
each channel by connecting them (together, or parallel them) with any other amplifier output.
* When speakers are connected through speaker, please make sure correct connection of each pin, and
refer speaker pin number.
• STEREO MODE • BRIDGED MODE
4. AC POWER
Plug this AC input cord into AC outlet.
FANS (QD-4240/4480)
The fans should be kept free of all obstructions and be accessible to cool fresh air when possible. It is
important that the fans be used in a dust free environment.
Fans are located in the Amplifier inside.
STEREO MODE, BRIDGED MODE AND PARALLEL MODE
• STEREO MODE
In this mode, each channels operate independently (typical quard amplifier). Channel 1 input signal feeds
channel 1 power amp, and channel 2 input signal feeds channel 2 power amp (channel 3 and 4 are operate
same as channel 1 and 2). In this mode, the minimum speaker impedance per channel is 4Ω.
• BRIDGED MODE
In this mode, channels 1, 2 or 3, 4 are bridged together and work as one mono amplifier. In this mode, the
minimum speaker impedance is 8Ω. (Caution: In this mode, channel 2 and 4 volume is set maximum position
(0)).
• PARALLEL MODE
In this mode, channels 1 and 2 are operate two mono amplifier. In this mode channel 1 input signal feeds
channel 1 and channel 2 power amp, the minimum speaker impedance per channel is 4Ω. Also, channel 3 and
4 are operate same as channel 1 and 2.
66
~AC INPUT
230V,50Hz 420W
QUAD AMPLIFIER
MODEL NO : QD-4480
CH 1
CH 4
CH 3
STEREO
BRIDGED
PARALLEL
: BRIDGED:240W(8Ω)X2
OUTPUT POWER : STEREO:120W(4Ω)X4
STEREO
BRIDGED
PARALLEL
OUTPUT
INPUT
OUTPUT
INPUT
CH 1(4Ω~8Ω)
CH 2(4Ω~8Ω)
BRIDGE
(8~16Ω)
CH 3(4Ω~8Ω)
CH 4(4Ω~8Ω)
BRIDGE
(8~16Ω)
CAUTION;
TO REDUCE THE RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS
INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
AVIS;
RISQUE DE CHOC ELECTRIOUE NE PAS OUVRIR.
CH 1
BRI
CHA
IS "O
CHA
CON
PUSH
PUSH
CH 2
CH 1
PUSH
PUSH
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
(4Ω min)
(4Ω min)
(4Ω min)
(4Ω min)
S/N
MADE IN KOREA
(8Ω min)
(8Ω min)
CH 1
CH 3
CH 2
CH 4
BRIDGED MONO USE
CHANNEL 2, 4 CONTROL
IS "O" POSITION, ONLY
CHANNEL 1 AND 3
CONTROL ADJUSTS GAIN
~AC INPUT
230V,50Hz 420W
QUAD AMPLIFIER
MODEL NO : QD-4480
CH 1
CH 4
CH 3
STEREO
BRIDGED
PARALLEL
: BRIDGED:240W(8Ω)X2
OUTPUT POWER : STEREO:120W(4Ω)X4
STEREO
BRIDGED
PARALLEL
OUTPUT
INPUT
OUTPUT
INPUT
CH 1(4Ω~8Ω)
CH 2(4Ω~8Ω)
BRIDGE
(8~16Ω)
CH 3(4Ω~8Ω)
CH 4(4Ω~8Ω)
BRIDGE
(8~16Ω)
CAUTION;
TO REDUCE THE RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS
INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
AVIS;
RISQUE DE CHOC ELECTRIOUE NE PAS OUVRIR.
C
B
CH
IS
CH
CO
PUSH
PUSH
CH 2
CH 1
PUSH
PUSH
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
S/N
MADE IN KOREA
SPEAKER IMPEDANCE
QD-4240/QD-4480 series amplifier has three operating modes: Stereo, Bridged and Parallel and allows you to
connect multiple speaker systems in parallel. Therefore, the minimum speaker impedance various depending on
the combination of these speakers. Be sure that the speaker impedance falls below the specified impedance.
The figures below show the examples of connection is Stereo mode and Bridged mode, and speaker systems
connected in parallel in Stereo mode, and the respective minimum impedance.
STEREO MODE CONNECTIONS
BRIDGED MODE CONNECTIONS
77
10mm
POWER AMPLIFIER
SPEAKER SYSTEM
FUSE
CAUTION FOR SPEAKER CONNECTION
1. Turn off the POWER switch.
2. After removing approx. 10 mm of insulation from the ends of the speaker cables, pass the bare ends of the
speaker wires through the holes in the corresponding speaker terminals and tighten the terminals to securely
clamp the wires.
Refer to page 4 for speaker porality.
At this time make sure that the bare ends of the speaker cables do not extend from the terminals in such a
way that they touch the chassis.
Wire should not
touch the chassis
• SPEAKER FUSE
The output capacity of this amplifier is high: 120W
the QD-4480: 60W
speaker system that has sufficient input capacity .
If the input capacity of your speaker system is lower than the rated output of the power amplifier, you can
protect your speakers by connecting a fuse serially between the speaker and amplifier as shown below.
4CH (4Ω) in stereo and 120W 2CH (8Ω) in monaural on the QD-4240. Besure to use a
4CH (4Ω) in stereo and 240W 2CH (8Ω) in monaural on
Use the following formula to determine the fuse capacity according to the speaker’s input capacity.
CH
1
CH 1
PUSH
PUSH
PUSH
PUSH
88
Po = I2R I =
Po
R
P0 [W]: Speaker’s continuous input capacity (noise or RMS)
R [Ω] : Speaker’s nominal impedance
I [A] : Required fuse capacity
ex.) Speaker’s continuous input capacity: 100W
Speaker’s impedance: 8Ω
100
I = = 3.5
8
In this example, the required fuse capacity is calculated as 3.5 [A].
• SPEAKER CABLE
If you use a long speaker cable, use as thick a cable as possible to prevent deterioration of the damping factor
or power loss inside the cable. Even the thickest cable can be used for the speaker terminal of this unit.
PORTABLE RACK MOUNTING
The amplifier intakes cool air through the front panel and exhausts warm air out the rear panel. When mounting
amplifiers in a portable rack, make sure the rear panel is completely open for ventilation.
Air intake
(Side View)
Front
Air exhaust
(Rear View)
Completely open
99
POSITIONING THE HOUSED AMPLIFIER
Place the case so that the ventilation airflow paths are not blocked.
Front
Less than 10 cm
Front
NO
NO
TROUBLESHOOTING
The following table lists the main causes of abnormal operation and the corrective measures required, as well
as the protective circuit operation in each case.
Indicator Probable Cause Remedy Protection Circuit
CLIP indicator
lights.
There is a short at a
speaker terminal,
amplifier terminal, or
wire.
The amplifier load is
excessive.
Locate and correct the
cause of the short.
Use a speaker system
with an impedance of at
least 4Ω (stereo) or 8Ω
(bridge).
The PC limiter circuit
operates to protect the
power transistors.
Same as above.
The heat sink
temperature has
exceeded 100˚C.
PROTECTION
indicator lights.
DC voltage of +/–2V
or greater was generated
in the power amplifier’s
output circuit.
Check the amplifier
ventilation conditions
and take appropriate
measures to improve
airflow around the
amplifier.
Consult your dealer. The relay operates to
The thermal protection
circuit operates to
protect the power
transistors.
protect the speaker
system.
CONNECTIONS
~AC INPUT
230V,50Hz 420W
QUAD AMPLIFIER
MODEL NO : QD-4480
S/N
MADE IN KOREA
CH 1
CH 4
CH 3
STEREO
BRIDGED
PARALLEL
: BRIDGED:240W(8Ω)X2
OUTPUT POWER : STEREO:120W(4Ω)X4
STEREO
BRIDGED
PARALLEL
OUTPUT
INPUT
OUTPUT
INPUT
CH 1(4Ω~8Ω)
CH 2(4Ω~8Ω)
BRIDGE
(8~16Ω)
CH 3(4Ω~8Ω)
CH 4(4Ω~8Ω)
BRIDGE
(8~16Ω)
CAUTION;
TO REDUCE THE RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS
INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
AVIS;
RISQUE DE CHOC ELECTRIOUE NE PAS OUVRIR.
CH 1
CH 1
CH 3
CH 2
CH 4
BRIDGED MONO USE
CHANNEL 2, 4 CONTROL
IS "O" POSITION, ONLY
CHANNEL 1 AND 3
CONTROL ADJUSTS GAIN
PUSH
PUSH
CH 2
CH 1
PUSH
PUSH
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
AUDIO MIXER
MIC
GUITAR
GROUP 4
GROUP 3
SPEAKER 4
SPEAKER 3
GROUP 2
GROUP 1
SPEAKER 1
SPEAKER 2
SINGLE AMP SYSTEM
1100
1111
~AC INPUT
230V,50Hz 420W
QUAD AMPLIFIER
MODEL NO : QD-4480
CH 1
CH 4
CH 3
STEREO
BRIDGED
PARALLEL
: BRIDGED:240W(8Ω)X2
OUTPUT POWER : STEREO:120W(4Ω)X4
STEREO
BRIDGED
PARALLEL
OUTPUT
INPUT
OUTPUT
INPUT
CH 1(4Ω~8Ω)
CH 2(4Ω~8Ω)
BRIDGE
(8~16Ω)
CH 3(4Ω~8Ω)
CH 4(4Ω~8Ω)
BRIDGE
(8~16Ω)
CAUTION;
TO REDUCE THE RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS
INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
AVIS;
RISQUE DE CHOC ELECTRIOUE NE PAS OUVRIR.
CH 1
CH 1
CH 3
CH 2
CH 4
BRIDGED MONO USE
CHANNEL 2, 4 CONTROL
IS "O" POSITION, ONLY
CHANNEL 1 AND 3
CONTROL ADJUSTS GAIN
PUSH
PUSH
CH 2
CH 1
PUSH
PUSH
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
TIP=HOT
RING=COLD
SLEEVE=GND
BALANCED INPUT 0dBm
TRS
1:GND
2:HOT
3:COLD
XLR
AUDIO MIXER
SPEAKER
SPEAKER
R
L
S/N
MADE IN KOREA
CONNECTIONS
BRIDGED MONO OPERA TION
1. Set mode selector to bridged mono.
2. Set the Channel 2 and 4 VR to maximum (0) position.
3. Connect a mono input signal to channel one input jack.
4. Connect the speaker load to the two red terminals of each channel,
please confirm the (+) terminal of speaker to channel one and the (–)
terminal to channel two.
5. Do not use the black terminals of each channel.
6. Please notice to connect the speaker impedance 8ohm or above.
SPECIFICATIONS
Power Output Level
f=1KHz, THD+N≤0.05% (Typical)
QUAD RL=8Ω
RL=4Ω
BRIDGED STEREO RL=8Ω
One Channel Driven
f=1KHz THD+N≤0.05% RL=4Ω
Frequency Response RL=8Ω, P.=1W
Power Bandwidth Half Power, THD+N≤0.1%
STEREO RL=8Ω
Total Harmonic Distortion (THD+N)
f=20Hz~20KHz, Half Power
STEREO RL=8Ω
RL=4Ω
BRIDGED RL=8Ω
Channel Separation Half Power RL=8Ω,
f=1KHz, ATT. max. Input 600Ω shunt
Residual Noise (DIN Audio Filter)
Signal-to-Noise Ratio DIN Audio,
Input 600Ω Shunt
Sensitivity (ATT max.)
Rated Power into 4Ω 1KHz
Input Impedance (ATT max.)
Indicators
Protection
PC Limiter
Fan Circuit
1122
QD-4240 QD-4480
40W 80W
60W 120W
120W 240W
60W 120W
0dB+0.5, –1.5dB: f=DC~55KHz
10Hz~70KHz
≤ 0.05%
≤ 0.07%
≤ 0.07%
≥ 80dB
≤ –70dB: ATT min.
≥100dB
0dBm
≥ 20KΩ (Balance/Unbalance)
Power (Red)
Protection (Mute) x 4 (Red)
Clip x 4 (Red)
Signal x 4 (Green)
Power SW ON/OFF muting
Heatsink Temp ≥ 100˚C (212˚F)
RL < 2Ω
–50˚C (122˚F)–60˚C (140˚F)–
Low-Speed – Variable – Hi-Speed
Controls
Power Source
Power Consumption
Weight
Dimensions
Connectors
* 0dB=0.775 Vrms, Half Power=1/2 Power Output Level (Rated Power)
* Specifications and design are subject to change without notice for improvement.
(Front) Power SW: Push up On/Push down Off
Attenuator: 21-position dB calibrated
(Rear) Mode Sw: Bridge=BTL/STEREO/PARALLEL
UL & Canadian Model: 120V, 60Hz
General Model: 230V, 50Hz
British Model: 240V, 50Hz
300W 420W
11.5kg 15.5kg
482(W) x 88(H) x 369(D) mm
Input : Combination Jack (balanced)
Output: 5-Way binding posts x 4
MADE IN KOREA
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