2 x 45mm 4ohm 4Ω 3W Stereo Speaker with PH2.0 Plug

Jargon buster

Plain-language definitions for the technical terms used above.

ESP32

ESP32 is a family of low-cost microcontroller chips and modules from Espressif with built-in WiFi and Bluetooth. They support programmable firmware and over-the-air updates, and are commonly programmed with toolchains such as the Arduino core and ESP-IDF.

Impedance

Impedance is the total opposition a component or circuit presents to alternating current, measured in ohms, combining resistance with frequency-dependent reactance. It appears in many contexts, such as matching a speaker's impedance (for example 4 ohm or 8 ohm) to an amplifier or the input and output impedance of signal circuits, and a correct match helps avoid weak signals, distortion or damage.

microcontroller

A microcontroller is a small computer on a single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.

single-board computer

A complete computer built onto one circuit board, usually including the processor, memory, ports, and connectors. This matters because accessories like heatsinks must match the board’s layout and mounting holes to fit properly.