【Bluetooth & 3.5mm AUX】 The ZK-MT21 power amplifier board uses Bluetooth 5.0, and its transmission distance can reach 49 feet (without obstruction). At the same time, this power amplifier board has a 3.5mm AUX audio input interface. No matter what kind of input method, you can always find a method that suits you.【Treble and bass adjustment】If you are tired of power amplifiers with only a single volume knob, then you feel right, because you have further requirements for audio. By adjusting the high and low frequency knobs of ZK-MT21, you can make the sound more layered and make the bass more shocking.【High compatibility】The DC adapters on the market (plug specification 5.5mm*2.1mm) basically can meet the needs of the ZK-MT21 Bluetooth power amplifier board. If your existing DC power plug is not 5.5mm*2.1mm, there is no The problem is because we have included a DC conversion plug in the product.【Protection function】ZK-MT21 Bluetooth power amplifier board has multiple protection mechanisms to ensure its safe operation. It has short-circuit protection, over-current, over-heat, and anti-reverse protection. When an overload occurs, the device reports the fault condition to the processor to protect itself from damage【7 * 24 Hours After-sales Service】 Paying Attention To Customer Experience And Satisfying Customers Is Our Service Tenet. If You Have Any Questions About The Product, or The Product Has Quality Problems, Please Contact Us At Any Time, We Will Give You A 100% Satisfactory Answer Product Description Input Mode AUX/Bluetooth AUX/Bluetooth/USB AUX/Bluetooth/USB AUX/Bluetooth AUX/Bluetooth AUX/Bluetooth Chip Other Chip TDA7498E TDA7498E TPA3116D2 TPA3116D2 TPA3116D2 MAX Power Output Per Channel 50W+50W+100W 160W+160W+220W 160W+160W 50W+50W+100W 100W+100W 100W+100W Working Voltage DC12-24V（Voltage is recommended Less than 20V） DC 15-36V DC 15-36V DC12-24V DC12-24V DC 9-24V(Recommended Above 12V/5A) Recommended speaker parameters 20-100W(4-8Ω） 30-200W(4-8Ω） 30-200W(4-8Ω） 20-100W(4-8Ω） 20-200W(4-8Ω） 50-300W(4-8Ω） Treble& Bass Controlotection × Heat Dissipation 36*25*10mm Heat Sink Long-life low-noise fanink Long-life low-noise fanink 50*25*10mm Heat Sink 36*25*10mm Heat Sink 36*25*10mm Heat Sink Dial Button × × × × ZK-MT21 Bluetooth power amplifier board parameters Model: ZK-MT21Bluetooth Version: 5.0 (Without occlusion 49 Feet)Audio Input: AUX + BluetoothChannel: 2.1 StereoAdaption Supply Voltage: 12-24V / 5A aboveSpeaker: 20-100W, 4-8OhmOutput Power: max 50W R&L channel; max 100W subwooferProtection Mechanism: Anti reverse connection, overheating, overcurrent, short circuit protection NOTE: Please note that this product does not include a power supply, you need to equip it with a DC power supply. It is recommended to use a DC power supply within 20V. If you use a battery pack to supply power, make sure that the battery voltage is lower than the rated voltage when the battery is fully charged. Independent Treble & Bass Control Comes with independent treble and bass control so you have more sound choices. A small power amplifier can also create a small movie theater for you. If you give it enough energy, with a 5-inch-6.5-inch speaker, it can give you a value-for-money experience. High compatibility and versatility 1. In addition to the Bluetooth input method, this power amplifier board can also input audio through AUX, and all 3.5mm AUX cables on the market can be used; 2. Regardless of whether your speaker cable has wiring terminals, it can be quickly and conveniently connected to the ZK-MT21 power amplifier board; 3. The universal 5.5mm*2.1mm DC power interface can be compatible with most of the DC power adapters on the market. Of course, this product also comes with a DC adapter to solve your worries about not having a 5.5mm*2.1mm plug. Additional base for Bluetooth antenna As some customers need additional Bluetooth antennas, we reserve a Bluetooth antenna base for customers, Under normal circumstances, you do not need to add an additional Bluetooth antenna for it, only when you install the power amplifier board in a closed metal box, you need to add an additional Bluetooth antenna.