Quantum Audio QA3X Service manual
3-WAY ELECTRONIC CROSSOVER
INSTALLATION INSTRUCTIONS
OWNER’S MANUAL
QA3X
tel: (956) 428-4263 fax: (956) 421-4513
www.quantumaudio.net
The Quantum QA3X is a full-featured Three-Way Crossover. When used to
build a 2-way systemwith front andrear fader capability or a full three-way
system,the Quantum QA3X electronic crossover allows you to choose from a
wide range of crossover points between the front, rear and subwoofer outputs.
The QA3X includes the following features:
• Selectable 2/4/6 Channel Input
• Independent Front / Rear / Subwoofer Input
•Continuously Variable Output Gain Controls for Front / Rear / Subwoofer
• Parametric Subwoofer Output Equalizer
• Frequency Multiplier for High-Pass Crossover
• Selectable 41Hz - 60Hz Subwoofer Crossover
• 18dB Subwoofer Bass Boost
• Remote Subwoofer Level Control
• Gold-Plated RCA Input / Output Connectors
• Power-on LED
The Quantum QA3X has the ability to accept one, two or three sets of RCA
cables as an input.
Both the front and rear outputs of the QA3X make use of a built-in 18dB per
octave electronic crossover that is continuously variable from 32Hz to 8kHz.
The subwooferoutput also uses an 18dB electronic crossover, and it is
adjustable from 45Hz to 250Hz.
The dash mounted bass level control provides a convenient way to adjust the
bass to suit your taste without having to leaveyour seat.
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FEATURES
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1. Front RCA Input
2. Front Crossover Frequency Control
3. Front/Rear Input Selection
4. Rear RCA Input
5. Rear Crossover Frequency Control
6. Sub Input Selection Switch
7. Sub RCA Input
8. Sub Crossover Frequency Control
9. Frequency Multiplier Switch
10. Sub Bass Boost Frequency
11. Sub Bass Boost Level
12. Ground Input Connector
13. Battery +12V Input Connector
14. Remote Turn-On Input
15. Front RCA Output
16. Front Output Level
17. Rear RCA Output
18. Rear Output Level
19. Phase Switch
20. Sub RCA Output
21. Sub Output Level
The top panel of the QA3X contains controls for the crossover and
output levels as shown below.
The QA3X includes the following features:
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FRONT PANEL CONTROLS
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2
3
5
6
8
9
10 11
13
12
14
15
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20
16
18
19
21
•Front High-Pass Crossover Frequency Adjustment - Adjusts the crossover
to match your speaker system. The crossover frequency can be adjusted from
32Hz - 400Hz or from 640Hz - 8kHz with the crossover frequency multiplier
switch.
•Rear High-Pass Crossover Frequency Adjustment - Adjusts the crossover
to match speaker your system. The crossover frequency can be adjusted from
32Hz - 400Hz.
•Subwoofer Crossover Frequency Adjustment - Adjusts the crossover to
match your speaker system. The crossover frequency can be adjusted from
45Hz - 250Hz.
• Frequency Multiplier Switch - When engaged, this switch increases the
crossover frequency by a factor of 15. Example: If the frequency is set for
70Hz, moving the frequency multiplier switch to X15 changes the setting to
1.05kHz.
•Output Level Controls - Seperate Front, Rear and Subwoofer Output Level
Controls allow you to set the nominal operating level of the crossover. The
crossover’s output level ranges can accommodate virtually any brand of
amplifier.
•Subwoofer Boost Control - The crossover also features a “high-Q” (i.e.
narrow frequency band) Bass Boost circuit. It acts much like an equalizer,
with adjustable gain (from 0 - +18dB) with a center frequency adjustable from
25Hz- 100Hz. Use this feature to tune low-frequency audio response to
compensate for a less than ideal subwoofer enclosure design. The added
boost produces rich, full bass tones that are normally difficult to reproduce in
the car audio environment. Use the Freq dial to set the Boost Freq and the
Sub Boost Level dial to set the amount of boost. Note: If Bass Boost is
undesired, set the Sub Boost Level to 0dB.
•Phase Switch- When set to 180 degrees, this switch reverses the phase of
the subwoofer output signal. This is used for fine tuning the bass response
after the installation is complete.
•Power Indicator - The power indicator will light up when the crossover is on.
•Front/Rear Input Switch - This switch allows use of a 2 channel input to
drive both the front and rear inputs.
•Sub Input Switch - This switch allows the signal from the front and rear
channels to be directed to the sub input when a dedicated sub input is not
available.
•Remote Sub Level Control - When the remote sub level control is plugged
into the QA3X, the sub output level control on the QA3X will be defeated.
Instead the remote sub level control will set the sub output level.
FEATURE DESCRIPTION
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The QA3X crossover can be mounted in any convenient location in your vehicle
that allows access to the controls and is away from moisture. The flanges on the
chassis have mounting holes which can be used as a template for screw holes.
For easy system set-up, mount the crossover so the front panel controls will be
accessible after installation.
In addition, observe the following precautions:
1. Mount the crossover on a rigid surface. Do not install the crossover on
plastic or other combustible materials.
2. Prior to drilling, make sure proposed mounting holes will not cut into the
fuel tank, fuel lines, brake lines (under chassis), or electrical wiring.
3. Avoid mounting to subwoofer enclosures or areas prone to vibration.
MOUNTING LOCATION
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Read all wiring precautions. If you are not sure of the connections, contact
your authorized Quantum Audio dealer.
If you are using a source unit, without a remote turn-on lead, the QA3X can
be turned on with a switched accessory lead. You can find this accessory
power source in the factory harness at the back of the radio. It is the lead that
turns on and off with the key.
1. Before installation, make sure the source unit Power switch is in the OFF
position.
2. Disconnect the negative (-) lead of the battery before making any power
connections.
3. A clean chassis ground connection is critical to the performance of your
Clarion crossover. Use the shortest ground wire possible and securely connect
to the car chassis to minimize resistance and avoid noise problems.
4. Refer to Figure 3 when making electrical connections. Connect the
crossovers positive (+) lead via a fuse directly to the positive (+) terminal on
the battery. Use red-insulated 18-gauge (or larger) wire for the crossover’s
positive (+) power lead and the same-gauge black insulated wire for the
ground.
5. To avoid noise problems, run the crossover’s positive (+) power lead and the
amplifier’s positive (+) power lead along one side of the vehicle to the battery..
Run the remote turn-on wire and RCA audio cables down the center and route
the speaker wires along the remaining side. If wires must cross, run them
perpendicular to each other..
6. When creating passage holes for the power wire, use grommets to eliminate
any sharp edges created during drilling. This will protect the wire from being
nicked and causing a short circuit.
7. Extra cable can cause signal loss and act as an “antenna” for noise. Use
only high-quality RCA cables that are no longer than necessary to make a
direct connection with the source unit and amplifiers.
WIRING PRECAUTIONS
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’
POWER CONNECTIONS
CAR BATTERY
+12V
-
+
IN-LINE POWER FUSE
MOUNTED WITHIN 12"
FROM BATTERY RECOMM ENDED
(NOT PROVIDED)
94.7
RADIO'S REM OTE
TURN-ON OUTPUT
REAR RCA
OUTPUT
FRONT RCA
OUTPUT
REAR RCA
INPUT
FRONT RCA
INPUT
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2-Way System with Front and Rear Output
In this illustration, the QA3X is configured for two channel input with
dedicated amps for front speakers, rear speakers and subwoofer(s).
APPLICATIONS
CAR BATTERY
+12V
-
+
IN-LINE POWER FUSE
MOUNTED WITHIN 12"
FROM BATTERY RECOM M ENDED
(NOT PROVIDED)
94.7
RADIO'S REMOTE
TURN-ON OUTPUT
FRONT RCA IN
REAR RCA IN
SUB RCA IN
Optional Input
SUB AMP REAR AMP FRONT AMP
SUB RCA OUT
REAR RCA OUT
FRONT RCA OUT
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2-Way System with Front and Rear Output
(Switch Configurations)
APPLICATIONS
FRONT RCA IN
REAR RCA IN
SUB RCA IN
FRONT RCA IN
REAR RCA IN
FRONT RCA IN
For 2 channel input,
configure switches as shown
For 4 channel input with front and
rear fade, configure switches
as shown
For front and rear fade with
dedicated subwoofer input, configure
switches as shown
9www.quantumaudio.net
After all the wiring connections are made and before the system is turned on
for the first time, you need to make some basic adjustments. It is important that
the High-Pass and Low-Pass Frequency Controls are set correctly before
turning on the system for the first time.
Setting the CrossoverFrequency Controls
1. Set the crossover frequency controls to the frequency recommended by the
speaker manufacturer.. The following are some guidelines if this information
is not available:
•Most 6” speakers will operate down to 80 - 100Hz.
•Most 5” or 4” speakers will operate down to 100 - 150Hz.
•Most 3” speakers will not operate below 300Hz.
•Most subwoofers have decreased sound quality when operated above
150Hz.
Depending upon the size of the front and rear speakers and the type of subwoofer system, fine tuning these
adjustments may be required after the initial system set-up. Study the system design pages of this manual to
determine the proper settings for these controls. Speakers are easily damaged if they are crossed over at a
frequency below their usable range.
2. When making the high frequency adjustments, adjust the Low-Pass
frequency control and the low frequency amplifier gain. Usually, the Low-
Pass frequency should be set the same as the High-Pass frequency
.
NOTE: An exception will be when the front/rear speaker is too small to play down to a very low frequency and the
subwoofer sounds distorted trying to “play up” to meet the front/rear speaker. This may require a gap or difference
between the high and low settings. Although not ideal, this is sometimes neccessary to make the system work as
well as possible.
Setting the Front Output Level
Before setting front level controls, disconnect both the rear output and the
subwoofer output and follow the directions below.
1. Turn the output control level to the minimum setting.
2. Turn the amplifier gain controls to the minimum setting.
3. Turn the source unit on and increase the volume until distortion is heard,
then reduce volume to just below this point.
NOTE: This is the maximum usable musical signal forthis source unit. turning the volume beyond
this point will increase noise and distortion without an increase in musical signal. If you can increase
the source unit volume to maximum without audible disortion, raise the output level controls slightly
and begin again.
4. With the amplifier gains still at minimum and the source unit set at
maximum volume without distortion, raise the front output level control
until distortion is heard, then reduce gain to just below this point. This is the
maximum output level for this system. For best performance do not
increase beyond this point.
2-Way System with Front and Rear Output
(Adjusting your System)
APPLICATIONS
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Setting the Rear Output Level
Before setting rear level controls, disconnect both the front output and the
subwoofer output and follow the directions below
.
1. Turn the output control level to the minimum setting.
2. Turn the amplifier gain controls to the minimum setting.
3. Turn the source unit on and increase the volume until distortion is heard,
then reduce volume to just below this point.
NOTE: This is the maximum usable musical signal for this source unit. turning the volume beyond this point will
increase noise and distortion without an increase in musical signal. If you can increase the source unit volume to
maximum without audible disortion, raise the output level controls slightly and begin again.
4. With the amplifier gains still at minimum and the source unit set at
maximum volume without distortion, raise the rear output level control until
distortion is heard, then reduce gain to just below this point. This is the
maximum output level for this system. For best performance, do not increase
beyond this point.
Setting the Sub Output Level
1. Make sure all ouputs are connected and the front and rear output levels are
set correctly. Unplug the Remote Sub Level control cable.
2. Be sure the sub output level and amplifier gains are at their minimum
settings.
3. With the volume set at a medium level, slowly increase the sub level
control to the point where the subwoofer volume blends with the system.
4. If maximum sub output level does not provide enough subwoofer volume,
slightly increase the subwoofer amplifier gain until desired level is reached.
5. Fine tune the bass response using the Sub Boost Controls.
6. Plug the Remote Sub Level Control cable back into the QA3X crossover.
Setting the Sub Boost Level
1. Initially set the sub boost level to the minimum setting (i.e. 0dB).
2. Listen to a variety of music styles (e.g. Rock, Rap, etc.) and slowly
increase the Sub Boost control until a noticeable increase in low bass
response is perceived.
3. Slowly adjust the Sub Boost Frequency control (up or down) to realize the
best bass response.
CAUTION: This feature can make a subwoofer put out more energy at very low frequencies. Be cautious with this
control because with too much boost at low frequencies the power handling of the subwoofer will be decreased.
This is a subjective setting and will depend on your personal listening preferences. If you hear a “pop” (due to
over-excursion), lower the Sub Boost to prevent speaker damage. If the system sounds muddy and distorted (due
to amplifier clipping), lower Sub Boost to avoid shutdown from overheating.
2-Way System with Front and Rear Output
(Adjusting your System - cont.)
APPLICATIONS
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3-Way System
In this illustration, the QA3X is configured for single channel input
with dedicated amplifiers for tweeters, midranges, and subwoofer(s).
APPLICATIONS
D
CAR BATTERY
+12V
-
+
IN-LINE POWER FUSE
MOUNTED WITHIN 12"
FROM BATTERY RECOM M ENDE
(NOT PROVIDED)
94.7
RADIO'S REMOTE
TURN-ON OUTPUT
FRONT RCA IN
SUB AMP MID AMP HIGH AMP
SUB RCA OUT
MID RCA OUT
HIGH RCA OUT
12www.quantumaudio.net
After all the wiring connections are made and before the system is turned on
for the first time, you need to make some basic adjustments. It is important that
the High-Pass and Low-Pass Frequency Controls are set correctly before
turning on the system for the first time.
Setting the Crossover Frequency Controls
1. Set the crossover frequency controls to the frequency recommended by the
speaker manufacturer.
.The following are some guidelines if this information
is not available:
• Most tweeters will not operate below 5000Hz.
• Most 6” midranges will operate down to 80-100Hz.
• Most 5” or 4” midranges will operate down to 125-200Hz.
• Most subwoofers have decreased sound quality when operated above
150Hz.
Depending upon the size/type of the midranges and tweeters and the type of subwoofer system, fine tuning these
adjustments may be required after the initial system set-up. Study the system design pages of this manual to
determine the proper settings for these controls. Midranges and tweeters are easily damaged if they cross at a
frequency below their useable range.
2. The Low-Pass frequency should be set the same as the High-Pass
frequency.
NOTE: An exception will be when the midrange is too small to play down to a very low frequency and the subwoofer
sounds distorted trying to “play up” to meet the midrange. This may require a gap or difference between the high
and low settings. Although not ideal, this is sometimes necessary to make the system work as well as possible.
Setting the Front and Rear Output Levels
Before setting front and rear level controls, disconnect the subwoofer output
and follow the directions below.
1. Be sure the front and rear High-Pass crossovers are set properly.
NOTE: When the QA3X is used in a 3-way system, the front outputs must be connected to the tweeter, amplifier, and
the rear outputs must be connected to the midrange amplifier.
2. Turn the front and rear output level controls to their minimum setting.
3. Turn the amplifier gain controls to their minimum setting.
4. Turn the source unit on and increase the volume until distortion is heard,
then reduce volume to just below this point.
NOTE: This is the maximum usable musical signal for this source unit. Turning the volume beyond this point will
increase noise and distortion without an increase in musical signal. If you can increase the source unit volume to
maximum without audible disortion, raise the output level controls slightly and begin again.
5. With the amplifier gains still at minimum and the source unit set at maximum
volume without distortion, raise the front and rear output level controls until
distortion is heard, then reduce the gain to just below this point. This is the
maximum output level for this system. For best performance, do not increase
beyond this point.
3-Way System
(Adjusting your System)
APPLICATIONS
13 www.quantumaudio.net
Setting the Sub Output Level
1. Make sure all outputs are connected and both the front and rear output
levels are set correctly. Unplug the Remote Sub Level control cable.
2. Be sure the sub output level and amplifier gains are at their minimum
settings.
3. With the volume set at a medium level, slowly increase the sub level
control to the point where the subwoofer volume blends with the system.
4. If maximum sub output level does not provide enough subwoofer volume,
slightly increase the subwoofer amplifier gain until desired level is reached.
5. Fine tune the bass response using the Sub Boost Controls.
6. Plug the Remote Sub Level Control cable back into the QA3X
crossover.
Setting the Sub Boost Level
Troubleshooting your System
1. Initially set the sub boost level to its minimum setting (i.e. 0dB).
2. Listen to a variety of music styles (e.g. Rock, Rap, etc.) and slowly
increase the Sub Boost control until a noticeable increase in low bass
response is perceived.
3. Slowly adjust the Sub Boost Frequency control (up or down) to realize the
best bass response.
CAUTION: This feature can make a subwoofer put out more energy at very low frequencies. Be cautious with this
control because with too much boost at low frequencies, the power handling of the subwoofer will be decreased.
This is a subjective setting and will depend on your personal listening preferences. If you hear a “pop” (due to
speaker over-excursion), lower the Sub Boost to prevent speaker damage. If the system sounds muddy and
distorted (due to amplifier clipping), lower Sub Boost to avoid shutdown from overheating.
Problem:
Music is not loud enough with source unit turned up.
Solution:
Output Level Controls are set incorrectly.
Problem:
Music gets loud and distorted with source unit turned up only part way.
Solution:
Output Level Controls are set incorrectly.
Gain Controls on amplifiers are set incorrectly.
3-Way System
(Adjusting your System - cont. / Troubleshooting)
APPLICATIONS
Problem:
Green power indicator LED not on, there is no sound.
Solution:
Check the CONSTANT and REMOTE (Switched) wiring connections.
Check the GROUND wiring for good connections.
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Problem:
Midrange speakers “pop” with loud passages.
Solution:
High-Pass Frequency Control is set too low.
Gain Controls on amplifiers are set incorrectly. Reduce the gain setting on high
frequency amplifier.
Problem:
One channel does not operate.
Solution:
Swap left and right connections at the source unit. If the problem trades sides
in the vehicle, then the source unit is the defective. If the problem stays on the
same side, proceed on.
Swap left and right connections at the input to the crossover. If the problem
trades sides in the vehicle, then the wiring is defective between the source unit
and the crossover. If the problem stays on the same side, proceed on.
Swap the left and right High-Pass RCAs at the output of the crossover. If the
problem trades sides in the vehicle, then the crossover is defective. If the
problem stays on the same side, proceed on.
Swap the left and right High-Pass RCAs at the amplifier input. If the problem
trades sides in the vehicle, then the RCA cable is defective. If the problem
stays on the same side, proceed on.
Swap the left and right speaker connections at the output of the High-Pass
amplifier. If the problem trades sides in the vehicle, then the amplifier is
defective. If the problem stays on the same side, then the speaker or speaker
wiring is defective.
QA3X SPECIFICATIONS
Power Source:
Input Current:
Distortion:
Frequency Response:
S/N Ratio:
Seperation:
Crossover Slope:
Input Impedance:
Output Impedance:
Output Gain:
Output Voltage Level:
Dimensions:
14.4 Volts DC
0.5 Amp Max
0.01% THD
10Hz - 30kHz - 3dB
>100dB
60dB
18dB per octave
20K Ohms
100 Ohms
1:2 (+6dB)
5 volts max
152mm x 180mm x 43mm
Troubleshooting Your System / Product Specifications
Troubleshooting
15 www.quantumaudio.net
Tel : 956-428-4263 Fax : 956-421-4513
www.quantumaudio.net
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