Fosi Audio M03 User manual

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Fosi Audio M03 User Manual

Product Specifications
Mini compact but powerful! Fosi Audio M03 is a 200watts
min mono channel subwoofer amplifier, with a SUB/PBTL
switch. Switch to SUB, it's a subwoofer amplifier for diving
passive and powered subwoofers. Switch to PBTL, it's a full
frequency mono amp for driving passive speakers and
powered subwoofer. Built-in low pass filter for 20-300Hz
subwoofers, creating the ultimate home cinema experience.
Input Interface: RCA input
Product Adapter Input
Voltage Range:
AC 110V - 240V
Output: passive/active subwoofer +
passive speaker
Dimensions (L * W * H): 128.5*117.5*36mm
Net weight: 0.5kG
SNR: ≥ 106dB
THD: ≤ 0.03%
Power Adapter: 32V/5A
Frequency Response Range: 20Hz-20KHz(± 3db)
Bass Frequency Range: 20Hz-200Hz
Terminating Impedance: 4-8Ω
Max Power Output: 200 watts
Input Sensitivity: ≤ 0.2mV

Product Overview & Control
Functions
RCA Input
Active/ Powered
Subwoofer Output
6
7
Passive Speaker& Subwoofer Output
8
DC Input
9
Back Panel
Power Switch
Power Indicator Light
1
2
PBTL&SUB Selector
SUB Frequency Control
3
4
Volume Control
5
Front Panel
2
1
35
4
6
7 8 9
M0-3
POWER PBTL
SUB
SUB FREQ VOL
SUB OUT
R L +
AUDIO IN SPK OUT
MADE IN CHINA

Package Contents
Fosi Audio M03 *1
32V/5A Power Adapter *1
User Manual *1
Quick Setup
Active subwoofer for example
Step 1: Prepare M03, 32V power adapter, active subwoofer, two
RCA cables;
Step 2: Connect the SUB OUT of M03 to the active subwoofer via
RCA cable;
Step 3: Use RCA cable to connect your device to the AUDIO IN of
M03;
Step 4: Switch PBTL/SUB switcher to PBTL or SUB;
Step 5: Make sure the volume knob turned to the minimum and
turn off the power switch;
Step 6: Connect the 32V power adapter to the DC input;
Step 7: Adjust volume control knob and turn on the power switch.
Passive subwoofer/passive speaker for example
Step 1: Prepare M03, 32V power adapter, passive subwoofer/
passive speaker, speaker wires or banana plugs;
Step 2: Connect the M03 to the passive subwoofer/passive
speaker via the speaker wire, you can use the bare wire or
banana plugs;
Step 3: Use RCA cable to connect your device to the AUDIO IN of
M03;
Step 4: Switch PBTL/SUB switcher to SUB if you are using
passive subwoofer, and switch PBTL/SUB switcher to
PBTL if you are using passive speaker;

Package Contents
Fosi Audio M03 *1
32V/5A Power Adapter *1
User Manual *1
Quick Setup
Active subwoofer for example
Step 1: Prepare M03, 32V power adapter, active subwoofer, two
RCA cables;
Step 2: Connect the SUB OUT of M03 to the active subwoofer via
RCA cable;
Step 3: Use RCA cable to connect your device to the AUDIO IN of
M03;
Step 4: Switch PBTL/SUB switcher to PBTL or SUB;
Step 5: Make sure the volume knob turned to the minimum and
turn off the power switch;
Step 6: Connect the 32V power adapter to the DC input;
Step 7: Adjust volume control knob and turn on the power switch.
Passive subwoofer/passive speaker for example
Step 1: Prepare M03, 32V power adapter, passive subwoofer/
passive speaker, speaker wires or banana plugs;
Step 2: Connect the M03 to the passive subwoofer/passive
speaker via the speaker wire, you can use the bare wire or
banana plugs;
Step 3: Use RCA cable to connect your device to the AUDIO IN of
M03;
Step 4: Switch PBTL/SUB switcher to SUB if you are using
passive subwoofer, and switch PBTL/SUB switcher to
PBTL if you are using passive speaker;
Method 2: Banana plugs connection illustration
: Release the banana jacket;
: Loosen the screw;
: Insertion speaker wire and tighten the screw;
: Tighten the banana jacket;
: Insert the banana plug into the horn terminals of the
speaker and amplifier.
Note: Please make sure that the speakers’ wire are not attached
with each other, the speaker connection area is very
narrow, it is easy to cause the positive and negative
speakers’ wires to contact each other,
Step 5: Make sure the volume knob turned to the minimum and
turn off the power switch;
Step 6: Connect the 32V power adapter to the DC input;
Step 7: Adjust volume control knob and turn on the power switch.
How to connect the speaker wire?
Method 1: Bare wire connection illustration
: Release the horn terminals block terminals;
: Insert the two ends of the speaker wire into the
amplifier and speaker terminal holes;
: Tighten the horn terminals;
Note: Please make sure that the speakers’ wire are not attached
with each other, the speaker connection area is very
narrow, it is easy to cause the positive and negative
speakers’ wires to contact each other, which will result in
no sound output.
1
2
3
4
5
1
2
3
123

which will result in no sound output.
Troubleshooting/QA
1: All cables are connected, but no sound output?
• Check if the POWER indicator is on, and turn on the POWER if it is
not on.
• When the indicator light is still not on after turn on the power, you
can find a laptop power and connect to test whether it is the
machine fault or a power failure.
• If the indicator light is on, check whether the VOL knob is in the
minimum position. If so, turn clockwise to normal Volume
• If both of the above are normal, check the input device if it is
paused, mute, or the volume is minimized.
2: Why does the sound break?
• when the output power exceeds the normal power of amplifier,
there will be a large distortion. You can turn down the front
volume or the power amplifier volume, then it is ok.
3: Why do loudspeakers make a lot of electric noise?
• If you are not using the original factory standard power supply,
please replace the power supply before testing. Many power
supply in the market have large interference coefficient, which will
cause a lot of current sound.
• Check whether all the cables are fully inserted into the interface, if
the cable is not fully inserted, it will also produce electric noise.
Release Jacket Loosen Screw Insertion speaker wire
tighten screw Tighten Jacket
1 2 3 4
banana plug into
the horn terminals
5

4: Why is there an interference sound after connecting the
signal line?
• If you use unshielded signal lines, there will be interference
signals entering the power amplifier. If you hate the sound, you
are advised to use the shielded signal lines or unplug the signal
lines.
5: Why does the amplifier stop working after a period of
time? After a period of time off, it was working again.
• Normally in this case, the amplifier is overheat protected, and the
output power may have exceeded the designed power, so you can
lower the volume a little and try again.
6: Why does the amplifier stop working after a period of
time? After a period of time off, it was working again.
• The output range of different types of audio source devices is
different, the mobile phone is usually 0.35mV, and the CD is 1V.
The signal output amplitude of the sound source will directly
influence the volume.
7: Why the sound of the power amplifier is not very good
at the beginning, the high frequency is not clear, but after
working for 8 hours the sound is normal?
• Speaker and amplifier is a very sensitive equipment, also need to
know each other, and the matching process, usually the sound
will be good after the new power amplifier and the speaker work
more than ten hours.
8: If the power going in to this unit is 32v 5amp = 160
watts. How is this unit rated 200watts?
• 200watts is 'Peak' output. Since the power supply can only
provide a max of 160watts, it can not supply any more than
160watts continuous (even the 160watts number is nonsense,
Troubleshooting/QA
1: All cables are connected, but no sound output?
• Check if the POWER indicator is on, and turn on the POWER if it is
not on.
• When the indicator light is still not on after turn on the power, you
can find a laptop power and connect to test whether it is the
machine fault or a power failure.
• If the indicator light is on, check whether the VOL knob is in the
minimum position. If so, turn clockwise to normal Volume
• If both of the above are normal, check the input device if it is
paused, mute, or the volume is minimized.
2: Why does the sound break?
• when the output power exceeds the normal power of amplifier,
there will be a large distortion. You can turn down the front
volume or the power amplifier volume, then it is ok.
3: Why do loudspeakers make a lot of electric noise?
• If you are not using the original factory standard power supply,
please replace the power supply before testing. Many power
supply in the market have large interference coefficient, which will
cause a lot of current sound.
• Check whether all the cables are fully inserted into the interface, if
the cable is not fully inserted, it will also produce electric noise.

as that would likely be at 10% THD, and thus worthless). However,
the capacitor could provide a temporary peek bost to get 200watts
for a very, very brief period of time. Maybe a few milliseconds.
If you want to achieve 200w power, you can use 32V 8A or 32V 10A
power adapter.
9: I can't seem to fine the rms watts. Does anyone know
the true specs? power at 2 ohms, at four ohms.
• 200 watts is the MAX power output. It's RMS power output is RMS
150watts @ 4ohm, RMS 120watts @ 8ohm with 32V 5A power
supply, if you want to get more power, you can upgrade the power
supply with 32V 8A.
Hope this can help you. If you have any questions, please feel
free to contact us.
(Customer Service Email: [email protected])
10: Does the crossover frequency control work with the
RCA output to a powered sub as well as to the speaker
output to a passive sub?
• Yes, the crossover frequency control knob controls the passive
sub and powered sub output.
11: Can M03 be used on a 2-8ohm subwoofer or speaker?
• Yes, M03’s terminating impedance is 4 - 8 Ohm. 2 - 8 Ohm is in
this range.
4: Why is there an interference sound after connecting the
signal line?
• If you use unshielded signal lines, there will be interference
signals entering the power amplifier. If you hate the sound, you
are advised to use the shielded signal lines or unplug the signal
lines.
5: Why does the amplifier stop working after a period of
time? After a period of time off, it was working again.
• Normally in this case, the amplifier is overheat protected, and the
output power may have exceeded the designed power, so you can
lower the volume a little and try again.
6: Why does the amplifier stop working after a period of
time? After a period of time off, it was working again.
• The output range of different types of audio source devices is
different, the mobile phone is usually 0.35mV, and the CD is 1V.
The signal output amplitude of the sound source will directly
influence the volume.
7: Why the sound of the power amplifier is not very good
at the beginning, the high frequency is not clear, but after
working for 8 hours the sound is normal?
• Speaker and amplifier is a very sensitive equipment, also need to
know each other, and the matching process, usually the sound
will be good after the new power amplifier and the speaker work
more than ten hours.
8: If the power going in to this unit is 32v 5amp = 160
watts. How is this unit rated 200watts?
• 200watts is 'Peak' output. Since the power supply can only
provide a max of 160watts, it can not supply any more than
160watts continuous (even the 160watts number is nonsense,

Our website: www.fosiaudio.com
Amazon store: www.amazon.com/fosiaudio
Our Youtube channel: Fosi Audio
Our Facebook page: Fosi Audio
After-sale Service and Technical Support Email:
[e-mail]
[e-mail]
Warranty Information
• All Fosi Audio products have an 18-month limited warranty on
parts and labor from the date of purchase. Please contact us if
you have any problems.
About Fosi Audio
• Fosi Audio designs and builds innovative audio products with
all your music in mind. Great sound, simple but elegant
designs, high-quality materials, and truly useful features are
what Fosi Audio is about. We sincerely hope you get as much
enjoyment from our products as we’ve had to create them!
Fosi Audio Product’s User Manual

Comparison Section
Model
Bluetooth
Version
Picture
MAX Power
Output
Input Ways
Output To
Power
Supply
Size
-
200 watts
RCA
Passive
(Speakers+
Subwoofer)
+Powered
Subwoofer
32V/5A
128.5*117.5*36mm
-
100watts
RCA
Passive (Speakers
+Subwoofer)
19V/4.74A
257*215*65mm
5.0
160watts
Bluetooth
+ RCA
+ U-disk
Passive Speakers
+ Powered
Subwoofer
24V/4.5A
298.5*241*76mm
M03 M02 BL20C BT30D
5.0
50 wattsx2+
100 watts
Bluetooth
+ RCA
Passive(Speakers
+Subwoofer)
+Powered
Subwoofe
24V/4.5A
291*248*72mm