Bluetooth Power Amplifier Board 2.1 Channel 50W x2 +100W - Compact

In this review of the ZK-MT21 Bluetooth power amplifier board, the bottom line is simple: it is for DIY audio builders and small home theater setups that need a compact 2.1 amplifier with modern wireless input and noticeable low-end power. The board pairs Bluetooth 5.0 connectivity with a 3.5mm AUX input, delivers up to 2x50W for left and right channels plus 100W for a subwoofer, and includes bass and treble controls to shape the sound. For anyone building store audio, square speakers, or a compact living-room subwoofer system, this module offers a straightforward upgrade path with built-in protection and robust connector choices.

Key Features

• Bluetooth 5.0: Reliable wireless streaming up to about 49 ft without obstruction for simple pairing with phones and tablets.
• AUX input: A 3.5mm AUX port provides a wired option for devices that lack Bluetooth or for lower-latency connections.
• 2.1 channel power: Delivers a maximum of 2x50W for stereo channels plus 100W for a powered subwoofer to produce fuller home theater bass.
• Tone controls: Separate bass, treble and subwoofer frequency and volume knobs let users tailor the sound for music or movie playback.
• Protection features: Built-in short circuit, over-current, overheat and anti-reverse protections protect the board and connected speakers under fault conditions.
• Durable connectors: Uses a copper DC connector and fence-type terminal with a common 5.5mm x 2.1mm power jack to handle higher current without heating.

Who It's For

The ZK-MT21 suits hobbyists and installers building a compact home theater, store solicitation audio, or square speaker system who want both Bluetooth convenience and a proper subwoofer channel. Its tone controls and sub channel make it useful where a punchy low-end is desired without a bulky receiver.

Those who need calibrated, room-correction features, network streaming, or integrated user interfaces should look elsewhere; this board is best used by people comfortable wiring a module into speakers and a 12V-24V power source, and who accept basic physical controls rather than software tuning.

Pros & Cons

Pros

• Compact 2.1 design gives clear stereo plus a dedicated sub output for stronger bass impact.
• Bluetooth 5.0 and AUX provide flexible input options for phones and wired sources.
• Multiple protections reduce the risk of damage from short circuits, overcurrent, overheating, or reverse wiring.

Cons

• Module-style form factor requires DIY installation and a separate enclosure for permanent use.
• No onboard digital room-equalization or network streaming options for advanced systems.

Specifications

Model	ZK-MT21
Operating Voltage	DC 12V-24V
Output Power	2x50W + 100W (max)
Speaker Impedance	4-8 Ohm
Bluetooth Version	5.0 (up to 49 ft without occlusion)
Audio Inputs	Bluetooth + 3.5mm AUX
Protection	Short circuit, over-current, overheat, anti-reverse

Our Verdict

The ZK-MT21 is a practical, value-oriented amplifier board for DIYers and small home theater builders who want Bluetooth streaming plus a dedicated subwoofer channel. It combines useful tone controls, solid protection features, and durable connectors into a compact module; while not a polished consumer receiver, it represents good value where flexibility and raw power per dollar matter most.

Frequently Asked Questions

What power supply does this board require?
Use a DC 12V-24V supply capable of supplying at least 5A or higher depending on speaker load and desired output.

Can I connect passive 4 ohm speakers?
Yes, the board supports 4-8 Ohm speakers; ensure the supply current and speaker power ratings are suitable for 50W channels and 100W sub output.

Does it have protection against wiring mistakes?
Yes, it includes anti-reverse connection protection plus over-current, overheating, and short circuit safeguards.