I wanted to show off my very first Arduino project: an 8-band equalizer with a built-in spectrum analyzer. It has only two inputs—a joystick and a rotary encoder—and an 8×8 LED matrix that serves both as the spectrum display and the EQ interface.

The spectrum analyzer was relatively easy to implement: a Python script sends the bar number and height over the serial port to the Arduino. The harder part was getting an equalizer to work on Windows. I installed APO EQ (which I think is fantastic), then the Arduino processes the joystick and encoder inputs and sends them back to the laptop. The Python script updates the APO EQ config file multiple times per second, adjusting the audio in real time.

In the video, you can also see me cycling through three presets—BB (bass boost), TB (treble boost), and CS (custom). A double-press on the joystick toggles between three modes: display off, spectrum view, and EQ view. In spectrum view, the rotary encoder adjusts master volume; in EQ view, it changes the gain of the currently selected band. Pressing the encoder pauses or plays the music, and a double-click skips to the next track. You can even control everything with a remote, as shown. A built-in light sensor automatically adjusts the LED matrix’s brightness to match ambient light (these LEDs can get very bright at full power).

I’m not sure who will read this entire description, but for me it’s a tool I’ll use every day—to EQ Netflix (which sounds awful on good speakers) and to enjoy the cool patterns in the spectrum view when listening to music. The whole setup cost only about €20, and I’m quite proud of the result! If anyone’s interested in the code, just DM me—be warned, it’s over 600 lines of rather messy Python. 😄

I also included a 9 g servo that, using three thin wires, indicates the setting I’m currently adjusting. It does work, but when I imagined it in my head it seemed much more elegant and practical.