ARRAROWN ZK-AS21 Bluetooth 5.1 2.1 Class D Amplifier Board — 220W×2 + 350W Sub, USB/AUX, Tone Controls

The ARRAROWN ZK-AS21 is a compact 2.1-channel Class D amplifier module that delivers 220W to each stereo channel and up to 350W to a powered subwoofer, plus Bluetooth 5.1, USB and AUX inputs for flexible home audio use.

Whether you are upgrading passive bookshelf speakers, building a compact powered subwoofer, or creating a DIY home theater, the ZK-AS21 combines high output, modern wireless connectivity and onboard tone controls in a small footprint. It uses efficient TPA3255 class D amplifier chips and multiple protection features to support speakers rated 30–220W (3–8Ω) and a subwoofer up to 350W (2–8Ω). The board accepts DC 16–38V and benefits from higher supply current for peak output, while an ultra-silent cooling fan helps maintain reliability during heavy use.

How does the ZK-AS21 handle speaker power and impedance?

The amplifier supplies two high-power stereo channels and a dedicated sub output with separate volume and frequency adjustment. It’s designed to drive medium- to high-power passive speakers and a dedicated subwoofer when paired with an appropriate power supply.

• Left/right channels: 220W per channel (dependent on supply voltage/current and speaker impedance).
• Subwoofer channel: up to 350W output (2–8Ω compatible).
• Recommended speaker range: 30–220W for satellite speakers; subwoofer 30–350W.
• Requires DC 16–38V power; higher voltage/current increases available output (use supply rated above amplifier working power).

What connectivity and controls are available for daily listening?

Multiple input options let you connect smartphones, USB sticks, PCs, or a wired audio source. Onboard tone and crossover controls allow quick adjustments so the system matches room acoustics and personal taste.

• Bluetooth 5.1 for wireless streaming with improved range and stability (approx. 15 m / 49 ft).
• USB flash playback and USB sound card input for direct digital sources.
• 3.5mm AUX for wired devices; switchable from Bluetooth to AUX.
• Independent Treble/Bass knobs plus sub volume and 20–200Hz sub frequency adjustment for precise tuning.

What technology and protection features improve sound and durability?

The ZK-AS21 integrates modern amplifier ICs and low-noise preamps to keep distortion low and clarity high, while built-in protections guard the module and connected speakers. Cooling and circuit safeguards extend usable life under demanding conditions.

• Dual TPA3255 class D chips for efficient, high-definition output and low distortion.
• Six low-noise 5532 preamplifiers to boost signal quality and gain performance.
• Protections: over-voltage, under-voltage, over-temperature, and short-circuit protection.
• Long-life, ultra-silent cooling fan and covered case to assist heat dissipation and component safety.

How do I power and install the ZK-AS21 in my setup?

Installation is straightforward for anyone comfortable with speaker wiring and DC power supplies. Choose a power supply that meets or exceeds the amplifier’s voltage/current needs and observe speaker impedance recommendations for safe operation.

• Power input: DC 16–38V; recommended supply current 10A or higher depending on desired output.
• Connect two passive speakers to stereo outputs and a passive or active subwoofer to the sub output accordingly.
• Use shielded audio cables for AUX/USB connections to reduce noise; disconnect Bluetooth when using AUX if required.
• Mount the module in a ventilated enclosure and keep the fan intake unobstructed for best thermal performance.

Who is this for? The ARRAROWN ZK-AS21 is aimed at audiophiles and DIY builders who want a compact, high-output amplifier board for custom speaker systems or small home theaters. It suits users comfortable with basic wiring and selecting a compatible DC power supply who seek Bluetooth streaming, precise tone controls and high-efficiency Class D power for clean, loud playback without a bulky chassis.