Product Specifications

Fosi Audio BT20A is a Hi-Fi wireless stereo 2-channel amplifier that features 100W x 2 output, and Bluetooth 5.0 streaming range up to 50ft (15m), it is a mini power amp which is equipped with bass and treble control. Simple compact design but practical and powerful! Home Hi-Fi integrated amplifier designed for the customers who pursue Hi-Fi sound!

Audio Input:

Bluetooth / RCA

Bluetooth Version:

Bluetooth 5.0

Bluetooth Pair PIN Code:

0000 or 1234


≥ 98dB

Input Sensitivity:

≤ 280mV


≤ 0.5%

Max Output Power:

100W + 100W

Power Supply:

24V 4.5A

DC Input Range:

12 – 24V

Terminating Impedance:

2Ω – 8Ω

Bluetooth Transmission Distance:

Up to 50 Ft

Frequency Range:

20Hz – 20kHz (±1 dB)

Input Mode:

Bluetooth and Analog

Product Size:

130 x 100 x 35 mm

Product Weight:


Product Overview & Control Functions

Front Panel

① Power Switch ② Treble Control ③ Bass Control  ④ Volume Control   ⑤Power Indicator Light

Back Panel

⑥ RCA Input ⑦ DC 24V Input ⑧ Speakers Output ⑨ luetooth Antenna


Package Content

Fosi Audio BT20A Amplifier*1

AC Power Cord*1

24V Power Supply*1

Bluetooth Antenna*1

Instruction Manual*1

Quick Setup


Prepare 1: BT20A, 24V power supply, passive speakers, speaker

wires or banana plugs;

Prepare 2: Connect the BT20A to the passive speakers via the speaker wire or banana plugs;

Prepare 3: Connect the 24V power supply to the DC input;

Prepare 4: Toggle the power switch on the front panel upwards to turn on the BT20A amplifier.

Note: Be sure that the volume/power switch is in the OFF position

before connecting the power supply.

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 avoid the speaker wires being exposed and touching the amplifier casing, as this may cause a short circuit fault.

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 take care to avoid contact between the two banana

plugs and causing a short circuit fault as some of the banana plugs are metal cased.

Bluetooth for example

Prepare your Bluetooth device (take a phone as an example)

Step 1: Install the Bluetooth antenna to the BT20A.

Step 2: Turn on the Bluetooth on your phone and search.

“ Fosi Audio”or “Fosi Audio BT20A”, after connecting to BT20A, the indicator light shows blue light.

Step 3: Open the audio application, play and enjoy!

RCA Input for example

Prepare: audio source (take a phone as an example), a RCA cable or a 3.5mm AUX to RCA cable (some devices will need)

Step 1: Connect your phone to BT20A via a 3.5mm to RCA cable;

Step 2: After connecting to BT20A, the indicator light shows red light;

Step 3: Open the audio application, play and enjoy!

Note: Please keep the BT20A away from other electric device. The BT20A can’t use with a radio simultaneously.


1: What type of speakers work best with BT20A Amplifier?

  • Fosi Audio BT20A works great with any 2-8Ω passive

Note: please know that the BT20A amplifier is for passive speakers, not for powered speakers and subwoofer.

2: Why Bluetooth is intermittent?

  • Use another Bluetooth device to have a
  • Ensure that there is no interference from other electronic equipment between the BT20A and the audio
  • Put your device close to the
  • Replug the power

3: Why does the BT20A make serious noise when used together with a radio?

  • common feature of Class D power amplifiers is that they can cause serious noise when used with a radio, so we do not recommend using the BT20A with a radio or too close to

4: Can I connect a turntable to BT20A amp, why is the volume is extremely Low?

  • As for the turntables do not have a built-in preamp, you need to add an external phono preamp before connecting
  • As for the turntables which have a built-in preamp, you need to s witch the preamp on before connecting

5: Why does my power indicator not light up?

  • Please check that the AC power cord is securely connected to the power supply and to an AC power outlet.
  • Please check that the AC power outlet is supplying power, make sure the power LED on the power supply will stay
  • Please replace another power supply and try it 12-24V DC

power supply are suitable.

  • If you make sure the power supply is defective, please contact us for

6: Why does the sound is cracking or make a lot of electric noise?

  • Please make sure all the cables completely pushed into the devices, incompletely connection will cause this
  • Please remove all the inputs then check whether cracking noise disappear or not, the cracking maybe from the audio source or input
  • 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

7: Can I use headphone with this product?

  • No, the BT20A cannot be connected to headphones and only supports passive speakers.


8: How can I switch between Bluetooth input and RCA input?

  • You can connect this amp via Bluetooth as well as wired input. But if Bluetooth connects, playback from the RCA input is You need to turn off the Bluetooth from your device if you use RCA input when Bluetooth pairing.

Input priority: Bluetooth input > RCA input


9: Why there is no voice from my amplifier?

  • Please check whether the cable of power supply is connected to BT20A and whether the power indicator is
  • Make sure the BT20A’s indicator light is on when the power is turned on.
  • Please check that the BT20A and your source components are turned on and not set to minimum volume, if possible replace your source and test again.
  • Check that the wire connections from the audio source to each speaker in the amplifier are connected
  • Please check that the cable is not loose, damaged. Incomplete connection is one of the main reasons for no
  • Please make sure the Bluetooth is paired, if Bluetooth is connected, the playback of RCA input will be interrupted. If you want to connect this amplifier with a RCA cable, you need to interrupt the Bluetooth


10: My Bluetooth device cannot pair with BT20A?

  • Make sure that BT20A is powered


  • Make sure that BT20A is not paired with other
  • Make sure that the distance between your device and BT20A is not too long, close your device to BT20A to have a
  • Make sure there are no obstacles between your device and BT20A, obstacles will affect the Bluetooth operation
  • Please try to change another Bluetooth audio source to
  • Please reconnect the power supply to the BT20A, and move the BT20A to another room to have a
  • Restart the BT20A and then try to connect again, try to use another Bluetooth


11: How much power does this use in standby mode? Can this amp be left on all the time?

  • This is the class D amplifier, it will cost very low power when it is in standby mode. It can be connected all the time and it is safe without power consumption.


12: Sound quality is not good?

  • Make sure all the cables are fully
  • Adjust the treble and bass control of the power amplifier to achieve the right
  • Please try to change the sound source and cables to


13: Should I unplug the power cord?

  • If the item will not be used for a long time, please unplug the power plug to prevent the item from being burnt due to lightning


14: Can I bridge channel 1 and channel 2 to get 200watts?

  • NO, this amplifier can’t be


15: How can I connect BT20A to TV?

  • Because the BT20A has an RCA input, it can be connected to

a TV.


16: Can BT20A accept signal from a Bluetooth microphone?

  • If your Bluetooth microphone is a Bluetooth transmitter, then This amplifier is the Bluetooth receiver amplifier.


17: Why the sound cut in and cut out?

  • Try to reduce the sound of the sound
  • Try to change the audio source to
  • Reduce the volume of the treble and bass knob on the
  • Ensure that the positive and negative poles of the speaker output do not touch together. Some relatively large banana plugs are easy to touch together and cause a short


18: What is the difference between BT20A and BT10A?

  • Fosi Audio BT20A has 100 Watts*2 MAX power output, the Fosi Audio BT10A has 50 Watts*2 MAX power


19: Can I take the BT20A to other countries?

  • Yes, the wide voltage AC 110-240V for power input can be used in any country. You only need to match the power cord adapter of the corresponding


Any problems please leave a message to the customer support email address:

Comparison Section

  • 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.