Fosi Audio M03 Power Subwoofer Amplifier User Manual

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 a powered subwoofer. Built-in low pass filter for 20-300Hz subwoofers, creating the ultimate home cinema experience.

Product Overview & Control Functions

Front Panel

1. Power Switch
2. Power Indicator Light
3. PBTL&SUB Selector
4. SUB Frequency Control
5. Volume Control

Back Panel

1. RCA Input
2. Active/ Powered
3. Subwoofer Output
4. Passive Speaker& Subwoofer Output
5. DC Input

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 is turned to the minimum and turn off the power switch;
Step 6: Connect the 32V power adapter to the DC input;
Step 7: Adjust the 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 a passive subwoofer, and switch PBTL/SUB switcher to
PBTL if you are using passive speaker;
Step 5: Make sure the volume knob is turned to the minimum and turn off the power switch;
Step 6: Connect the 32V power adapter to the DC input;
Step 7: Adjust the volume control knob and turn on the power switch.
How to connect the speaker wire?
Method 1: Bare wire connection illustration

1. Release the horn terminals block terminals;
2.  Insert the two ends of the speaker wire into the amplifier and speaker terminal holes;
3. Tighten the horn terminals;

Note: Please make sure that the speakers’ wires are not attached to 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.

Method 2: Banana plugs connection illustration

1. Release the banana jacket;
2. Loosen the screw;
3. Insertion speaker wire and tighten the screw;
4. Tighten the banana jacket;
5. Insert the banana plug into the horn terminals of the speaker and amplifier.

Note: Please make sure that the speakers’ wire is not attached to 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.

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 the 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 has a large interference coefficient, which will cause a lot of current sounds.
   • Check whether all the cables are fully inserted into the interface, if the cable is not fully inserted, it will also produce electric noise.

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 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 into 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, 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 a 32V 8A or 32V 10A power adapter.

9. I can’t seem to find the RMS watts. Does anyone know the true specs? power at 2 ohms, at four ohms.
   • 200 watts is the MAX power output. Its 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.

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!

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:
[email protected]
[email protected]

Fosi Audio Product’s User Manual

Comparison Section

MAX Power
Output| 200 watts| 100watts| 160watts| 50 wattsx2+ 100 watts
Input Ways| RCA| RCA| Bluetooth + RCA
+ U-disk| Bluetooth + RCA
Output To| Passive (Speakers+
Subwoofer) +Powered
Subwoofer| Passive (Speakers
+Subwoofer)| Passive Speakers
+ Powered
Subwoofer| Passive(Speakers
+Subwoofer)
+Powered Subwoofer
Power Supply| 32V/5A| 19V/4.74A| 24V/4.5A| 24V/4.5A
Size| 128.5117.536mm| 25721565mm| 298.524176mm| 29124872mm

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