Fosi Audio BL20A Bluetooth 5.0 Stereo Amplifier User Manual

1. Introduction

The Fosi Audio BL20A is a 2.1 channel Bluetooth 5.0 power amplifier designed for home audio systems. It is capable of driving most passive, powered, bookshelf, or ceiling speakers. Featuring multiple input options including U-Disk, 3.5mm AUX, and RCA, along with bass, treble, and remote control, the BL20A offers versatile connectivity and sound customization. This amplifier utilizes two Texas Instruments TPA3116 power amplifier chips, providing up to 200 Watts of output power with built-in protection features.

2. Package Contents

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

3. Product Overview

Front Panel

Figure 1: Front and Rear Panel Layout of the BL20A Amplifier.

• IR: Infrared receiver for remote control.
• USB: U-Disk input (supports up to 32GB).
• Input Indicator Light: Red for AUX/USB, Blue for Bluetooth.
• BASS: Bass level control knob.
• TREBLE: Treble level control knob.
• MODE / VOL: Multi-function knob for power on/off (long press), mode switch (short press), and volume control (turn left/right).

Rear Panel

• INPUT: 3.5mm AUX input.
• PRE-OUT: 3.5mm AUX pre-output.
• OUTPUT: Speaker outputs (RCA terminals for passive speakers).
• ANT: Bluetooth antenna interface.
• DC 12-24V: Power adapter input.

Remote Control

Figure 2: Remote Control Functions for the BL20A Amplifier.

• Power Button: Short press to power on/off.
• Single Cycle/All Loop: When playing music in U-Disk mode, short press to switch between single loop or all loop playback.
• Mute Button: Short press to mute.
• Volume Down/Up: Short press to decrease/increase volume.
• Mode Switch: Short press to switch input mode (AUX/U-Disk/Bluetooth).
• Treble Down/Up: Short press to decrease/increase treble.
• Bass Down/Up: Short press to decrease/increase bass.
• Previous/Next Track: Only for Bluetooth or U-Disk mode.
• Play/Pause: Short press to play/pause. Long press in Bluetooth mode to disconnect Bluetooth.
• Number Buttons (0-9): Select specific songs in U-Disk mode.
• Fast Backward/Forward: Long press for fast backward/forward in U-Disk mode.

4. Setup Instructions

1. Install Bluetooth Antenna: Screw the Bluetooth antenna onto the ANT interface on the rear panel.
2. Connect Speakers: Use speaker wires to connect your passive speakers to the OUTPUT terminals (R for right, L for left) on the rear panel. Ensure positive and negative poles are correctly connected to avoid short circuits.
3. Connect Audio Source:
   • AUX Input: Use a 3.5mm audio cable to connect your audio device to the INPUT jack. The input indicator light will be red.
   • U-Disk Input: Insert a U-Disk (max 32GB) into the USB port. The input indicator light will be red and flash continuously.
   • Bluetooth Input: Short press the MODE knob/button to switch to Bluetooth mode. The input indicator light will flash blue during pairing and stay solid blue after a successful connection.
4. Connect Power: Connect the power adapter to the DC 12-24V input on the rear panel and plug it into a power outlet. Long press the MODE / VOL knob to power on the BL20A. The input indicator light will stay red after power-on.
5. Initial Volume Adjustment: Before connecting the power supply, turn down the bass and treble controls to 0 (always to the left) to avoid hearing damage.

5. Operating Instructions

Power On/Off and Mode Selection

• Power On/Off: Long press the MODE / VOL knob on the front panel or the power button on the remote.
• Switch Input Mode: Short press the MODE / VOL knob on the front panel or the MODE button on the remote to cycle through AUX, U-Disk, and Bluetooth inputs.

Volume, Bass, and Treble Control

• Volume: Turn the MODE / VOL knob left or right, or use the V-/V+ buttons on the remote.
• Bass: Turn the BASS knob left or right, or use the B-/B+ buttons on the remote.
• Treble: Turn the TREBLE knob left or right, or use the H-/H+ buttons on the remote.

Bluetooth Operation

• Ensure the Bluetooth antenna is installed.
• Switch the amplifier to Bluetooth mode (blue indicator light flashing).
• On your device (phone, tablet, laptop), search for "BL20A" and pair. The indicator light will turn solid blue upon successful connection.
• Maximum transmission distance is up to 50 feet (15 meters) without obstacles.
• To disconnect Bluetooth, long press the Play/Pause button on the remote.

U-Disk Operation

• Insert a U-Disk (USB flash drive) into the USB port. The indicator light will be red and flash continuously.
• Supported formats: MP3/WMA/APE/FLAC/WAV.
• Use the remote control for playback functions (Play/Pause, Previous/Next Track, Single Cycle/All Loop, Fast Backward/Forward, Number Buttons).

Media Integration

6. Troubleshooting

• Noisy music playback: Try using another Bluetooth device. Weak or unstable Bluetooth signal can cause this. Ensure no interference from other electronic equipment. For U-Disk, ensure format compatibility (MP3/WMA/APE/FLAC/WAV) and U-Disk capacity does not exceed 32GB. For AUX, try another RCA cable and ensure secure connections.
• No audio output when cables are connected: Check the input indicator light on the front panel and power supply. Ensure the volume knob is not at minimum. Make sure all cables are fully pushed into the device. Restart the BL20A and your device.
• Bluetooth device cannot pair: Ensure the BL20A is powered on and the LED light on the power adapter stays on. Make sure the BL20A is not paired with another device. Ensure your device is not too far from the BL20A (max 50ft/15m). Try another Bluetooth audio source. Replug the power supply. Move the amplifier to another room and test again. Restart the BL20A and your device.
• Intermittent Bluetooth: Ensure no interference from other electronic equipment. Put your device closer to the BL20A. Replug the power adapter.
• One channel does not work: Test whether Bluetooth, U-Disk, and AUX inputs have the same problem. If so, swap the speaker cables of the left and right channels. If the problem persists, test with another speaker.
• U-Disk cannot be played: Try other U-Disk playback tests. Ensure U-Disk capacity does not exceed 32GB.
• U-Disk play rustling: WAV format supports DTS multi-channel, which BL20A does not support. Download Foobar2000 software to convert the audio channel.
• Cannot power on: Long press the power switch button to power on/off. Make sure the LED light on the power adapter stays on. If not, unplug the power adapter from the BL20A, plug the power adapter directly into the AC power source, and see if the LED light lights up. If it still does not light up, there may be a problem with the power adapter. Contact support. Use a DC12-24V power adapter to test.
• BL20A can be used as a pre-amp: Yes, there is a PRE-OUT interface on the rear panel.
• Connect all outputs of BL20A: You don't need to connect all outputs. You can connect 2 passive speakers only, or connect it to the pre-out as a preamplifier. You can connect all outputs simultaneously.
• Sound quality is not good: Make sure all cables are fully connected. Adjust the treble and bass control of the BL20A. Try to change the sound source and cables.
• Sound cut in and out: Try to reduce the sound source. Try to change the audio source. Reduce the volume of the treble and bass knob. Ensure positive and negative poles of the speaker output do not touch.
• BL20A supports Bluetooth aptX and Low Latency: No, the BL20A does not support Dolby, aptX HD, and aptX Low Latency.
• Can this amp be left on all the time: It can be connected all the time and is safe without power consumption.
• Listen to two audio inputs at the same time: No, only one mode can be used at a time.

7. Specifications

8. Warranty Information

All Fosi Audio products have an 18-month limited warranty on parts and labor from the date of purchase. Please contact Fosi Audio customer support if you have any problems or require assistance.

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