Fosi Audio BL20A Bluetooth Power Amplifier User's Manual

Product Specifications

Product Overview

The Fosi Audio BL20A is designed for audiophiles, offering high-definition sound quality through its TPA3116 chips. It supports multiple input modes and is suitable for various home passive speakers.

Front Panel Controls:

• 1: Infrared Radiation: Receives signals from the remote control.
• 2: AUX/U-Disk/Bluetooth Input Indicator Light: Shows the current input mode (Red for AUX/USB, Blue for Bluetooth).
• 3: U-Disk Input: Port for connecting a USB drive.
• 4: Bass Control: Adjusts the bass level.
• 5: Treble Control: Adjusts the treble level.
• 6: Multi-function Knob (Power Switch/Mode Switch/Volume Control):
  • Long press to power on/off.
  • Short press to switch input mode (AUX, U-Disk, Bluetooth).
  • Turn left to decrease volume.
  • Turn right to increase volume.

The front panel layout includes the IR receiver, the indicator light, the USB input, Bass and Treble control knobs, and the central multi-function knob. The indicator light shows the input status: Red for AUX/USB input, and flashing Blue for Bluetooth pairing, solid Blue for a successful Bluetooth connection.

Rear Panel Connections

The rear panel provides the following connections:

• 7: INPUT: For connecting audio sources (e.g., 3.5mm AUX).
• 8: PRE-OUT: 3.5MM AUX pre-output for connecting to an amplifier or powered speakers.
• 9: SPEAKERS OUTPUT: Connects to passive speakers (Left and Right channels).
• 10: ANT (Bluetooth Antenna Interface): For attaching the Bluetooth antenna.
• 11: DC INPUT: Connects to the power adapter (DC 12V-24V).
• 12: Bluetooth Antenna: External antenna for improved Bluetooth reception.

Diagrams illustrate connections to Active Speakers, an Amplifier, and Passive Speakers, showing flexibility in setup.

Remote Control

The infrared remote control allows for convenient operation from a distance, with a working distance of up to 15 meters.

Remote Control Functions:

• 1: Power: Short press to power on/off the BL20A.
• 2: Loop Mode: Short press to switch between single loop and all loop playback for U-Disk music.
• 3: Mute: Short press to mute or unmute audio. ?
• 4: Volume Down: Short press to decrease volume. ➖
• 5: Volume Up: Short press to increase volume. ➕
• 6: Mode: Short press to switch input mode (AUX/U-Disk/Bluetooth). Note: U-Disk must be inserted for this mode to be available.
• 7: Treble Up: Short press to increase treble.
• 8: Treble Down: Short press to decrease treble.
• 9: Bass Up: Short press to increase bass.
• 10: Bass Down: Short press to decrease bass.
• 11: Previous Track: Short press to go to the previous track. Works in Bluetooth or U-Disk mode.
• 12: Next Track: Short press to go to the next track. Works in Bluetooth or U-Disk mode.
• 13: Play/Pause: Short press for Play/Pause. Long press in Bluetooth mode disconnects the Bluetooth connection. ▶️ / ⏸️
• 14: Number Buttons (0-9): Select a specific song in U-Disk mode. For songs ranked after 10, press numbers sequentially.
• 15: Fast Backward: Long press for fast backward playback. Works in U-Disk mode. ⏪
• 16: Fast Forward: Long press for fast forward playback. Works in U-Disk mode. ⏩

Package Contents

• BL20A Bluetooth Amplifier x 1
• Bluetooth Antenna x 1
• Remote Control x 1 (Battery not included)
• Power Adapter x1
• AC Cord x1
• User Manual x 1

Quick Setup

Follow these steps to set up your Fosi Audio BL20A amplifier:

1. Step 1: Install the Bluetooth antenna to the BL20A for optimal wireless reception.
2. Step 2: Connect speakers:
   • Use speaker wire to connect the BL20A's speaker output to your passive speakers.
   • Alternatively, use a 3.5MM audio cable to connect the BL20A's 3.5MM AUX pre-out to an external amplifier, then connect that amplifier to your passive speakers.
   • Or, use a 3.5MM audio cable to connect the BL20A's 3.5MM AUX pre-out directly to your powered speakers.

   You can connect two passive speakers only, or use the pre-out as a pre-amplifier. All outputs can be connected simultaneously.

3. Step 3: Connect the power adapter to the BL20A and a power outlet. Long press the Multi-function Knob to power on the BL20A. The input mode indicator light should turn red after power-on.

   Note 1: Ensure the LED light on the power adapter is on.

   Note 2: Before connecting power, turn the Bass and Treble controls fully counter-clockwise (to 0) to prevent hearing damage.

4. Step 4: Connect the audio source:
   • AUX Input: Use a 3.5mm audio cable to connect the BL20A to your audio device. The input indicator light will stay red.
   • U-Disk Input: Insert your USB drive into the U-Disk input interface. The input indicator light will be red and flash continuously.
   • Bluetooth Input: Short press the Multi-function Knob to select Bluetooth mode (indicator light flashes blue). Turn on Bluetooth on your device, select "BL20A" for pairing. The indicator light will stay solid blue upon a successful connection.

   Input priority: The latest input mode is prioritized.

   Please keep the BL20A away from other electric devices to avoid interference. The BL20A cannot be used with a radio simultaneously.

5. Step 5: Adjust controls and enjoy your audio.

   Ensure all cables are securely connected.

Q&A / Troubleshooting

1. Get noise when playing music?

• Bluetooth input: Try other Bluetooth devices. Weak or unstable signals can cause noise. Move your device closer to the BL20A.
• U-Disk input: Try other U-Disks. Ensure the audio format is compatible (MP3/WMA/APE/FLAC/WAV). Verify U-Disk capacity does not exceed 32GB and it is functioning correctly.
• AUX input: Try a different audio cable or RCA cable and ensure connections are secure.
• Unplug and replug RCA cables, then power cycle the amplifier.
• Try a different audio source or brand of device.
• Check if the "Treble" control is set too high; try reducing it.
• Ensure all cables are fully inserted, as loose connections can cause issues.
• Keep the BL20A away from other electronic devices.

2. All cables are connected, but there is no audio output?

• Check that the BL20A's input indicator light and the power supply are on.
• If the indicator light is on, check if the volume knob is at its minimum. Turn it up if necessary.
• Ensure the BL20A is in the desired playback mode (Bluetooth: solid blue light; AUX: red light; U-Disk: red flashing light).
• Verify U-Disk capacity is within 32GB and the disk is functional.
• Check if the audio source is paused.
• Try different sound sources, cables, and speakers.
• Restart the BL20A and your audio device, then try connecting again.

3. My Bluetooth device can't pair with the BL20A?

• Ensure the BL20A is powered on and the power adapter's LED is lit.
• Make sure the BL20A is not already paired with another device.
• Reduce the distance between your device and the BL20A.
• Ensure there are no physical obstacles between your device and the BL20A, as these affect Bluetooth range (max 164ft/50m without obstacles).
• Try pairing with a different Bluetooth audio source.
• Replug the power supply, move the amplifier to a different location, and test again.
• Restart the BL20A and your device, and try connecting again, possibly using a different brand of mobile phone.

4. Why Bluetooth is intermittent?

• Try using another Bluetooth device.
• Ensure there is no interference from other electronic equipment between the BL20A and your audio source.
• Place your device closer to the BL20A.
• Replug the power adapter.

5. One channel does not work?

• First, test if the issue occurs across Bluetooth, U-Disk, and AUX inputs.
• If the problem persists across all modes, swap the left and right speaker cables or try a different speaker.
• If the issue is specific to Bluetooth, U-Disk, or AUX, try changing the audio source, audio cable, and ensure all connections are secure.

6. U-Disk cannot be played?

• Try different U-Disk drives.
• Ensure the U-Disk capacity does not exceed 32GB and it is functioning correctly.
• Confirm the BL20A is in U-Disk playback mode.

7. U-Disk play rustling?

• This may be a song format issue. WAV files with DTS multi-channel audio are not fully supported; the BL20A supports stereo. Convert DTS to stereo using software like Foobar2000.

8. Can't power on?

• Long press the power switch button to power on/off.
• Ensure the power adapter's LED light is on.
• If the adapter's LED is off: Unplug the adapter from the BL20A, plug it directly into an AC power source. If the LED still doesn't light up, the power adapter may be faulty. Contact Fosi Audio for a replacement.
• You can test if the BL20A powers on by using a compatible DC 12-24V power adapter from a camera or router.

9. The BL20A can be used as a pre-amp?

Yes, the BL20A features a PRE-OUT interface on the rear panel that can be used as a pre-amplifier output.

10. Do I have to connect all the outputs of BL20A? Can I only connect 2 speakers? Or just use it as a preamp?

You do not need to connect all outputs. You can connect two passive speakers, use the pre-out as a pre-amplifier, or connect all outputs simultaneously.

11. Sound quality is not good?

• Ensure all cables are fully connected.
• Adjust the Treble and Bass controls on the BL20A to achieve the desired tone.
• Try changing the sound source and cables to test.

12. Why the sound cut in and cut out?

• Try reducing the volume of the audio source.
• Try a different audio source.
• Reduce the volume of the Treble and Bass knobs on the BL20A.
• Ensure the positive and negative poles of the speaker output do not touch each other, as this can cause a short circuit, especially with larger banana plugs.

13. Does the BL20A support Bluetooth aptX and Low Latency?

No, the BL20A does not support Dolby, aptX, aptX HD, or aptX Low Latency.

14. Can this amp be left on all the time?

Yes, the amplifier can be left connected and is safe to use without significant power consumption when idle.

15. Can I listen to two audio inputs at the same time?

No, only one audio input mode can be used at a time.

Warranty Information

All Fosi Audio products come with an 18-month limited warranty covering parts and labor from the date of purchase. Please contact Fosi Audio customer support if you encounter any issues.

About Fosi Audio

Fosi Audio designs and builds innovative audio products with a focus on great sound, simple yet elegant designs, and high-quality materials. They aim to provide enjoyable audio experiences.

Website: www.fosiaudio.com

Amazon Store: www.amazon.com/fosiaudio

YouTube Channel: Fosi Audio

Facebook Page: Fosi Audio

After-sale Service and Technical Support Email: support@fosiaudio.com, fosiaudio@hotmail.com