AS21P Bluetooth 5.1 2.1 Channel TPA3255 Power Amplifier Board - High

In this review the AS21P Bluetooth 5.1 digital power amplifier board is evaluated for DIY audio builders and custom home theater installs. The bottom line: it is a compact, high-power 2.1 amplifier module that delivers serious output for left/right speakers and a subwoofer, making it a strong choice for anyone needing flexible inputs and lots of headroom. Our review found the board best for users who can supply an appropriate DC source and want high-fidelity output without a full prebuilt receiver.

Key Features

• Bluetooth 5.1: Offers stable wireless streaming up to about 15 meters, convenient when adding the board to a living-room or workshop system.
• High output power: The 2.1 channel layout uses dual TPA3255 chips to deliver strong left and right channel power and a powerful dedicated subwoofer channel.
• Wide voltage range: Runs from 18 to 50VDC (limit 53V) so it adapts to different power supplies and gains output with higher voltage within safe limits.
• Multiple inputs: Supports Bluetooth, AUX and U disk sound card input methods for flexible source options in custom installations.
• Protections: Built-in undervoltage, overheating, overcurrent and short circuit protections help protect the amplifier during heavy use.

Who It's For

This board is ideal for experienced DIYers, custom home theater installers or hobbyists who want a compact amplifier with a dedicated sub channel and flexible inputs. The integrated potentiometer version simplifies control in a compact 15 x 12 x 4 cm package and is useful where space is limited but high power is required.

It is not for users who expect a plug-and-play powered speaker with a built-in regulated power supply; you must provide a suitable DC supply (recommended 36-48V with adequate current) and observe polarity carefully since there is no reverse-polarity protection. Novice users should seek a finished amplifier product instead.

Pros & Cons

Pros

• Very high potential output using dual TPA3255 chips for powerful stereo and subwoofer performance.
• Bluetooth 5.1 plus AUX and U disk support gives flexible connectivity for many setups.
• Robust protection features reduce risk of damage from common fault conditions during use.

Cons

• No input anti-reverse connection protection, so reversed power leads can damage the board if connected incorrectly.
• Requires an external DC supply sized for high current, which adds cost and assembly complexity for some users.

Specifications

Model	AS21P / AS21PB (potentiometer integrated)
Channels	2.1 (left, right + subwoofer)
Amplifier chip	Two TPA3255
Bluetooth	Version 5.1, ~15 m transmission distance
Working voltage	18-50VDC (limit 53V); recommended 36-48V
Physical size	Integrated potentiometer: 15 x 12 x 4 cm
Package contents	1 x potentiometer integrated AS21P (board only)

Our Verdict

The AS21P Bluetooth 5.1 2.1 amplifier board is a strong value for skilled builders who need high-power stereo and subwoofer capability in a compact module. It delivers flexible inputs and built-in protections, but expects the user to provide a proper DC supply and respect polarity. For DIY home audio projects that require serious output without buying a full receiver, it is an excellent choice.

Frequently Asked Questions

What voltage and current should I use?
Use a DC supply between 36 and 48V with sufficient current (for example 12A) to feed the high-power outputs safely.

Does it include protection circuits?
Yes. The board has undervoltage, overheating, overcurrent and short circuit protection but no reverse-polarity protection on the input.

What inputs are supported?
Bluetooth 5.1, AUX and U disk sound card input methods are supported for flexible source options.