This Raspberry Pi Pico-Powered USB Audio Box Delivers Room-Level Parametric Equalization
With up to eight audio channels, when powered by a Raspberry Pi Pico 2, shiura's project aims for the best response for any room.
Pseudonymous maker "shiura" wants to improve your music or film listening experience — by building a low-cost USB audio tool with integrated parametric equalizer for room-level audio adjustment.
"No matter how faithfully your speakers reproduce sound, the resonance of your room can ruin it," shiura explains. "'Room EQ' is a powerful technique for compensating for this, as it adjusts a parametric equalizer based on measurements to bring the frequency response at the listening point closer to flat. While this process can be done using software alone, using [a] physical device ensures consistent results across all devices, including smartphones."
Rather than going for an expensive off-the-shelf accessory, though, shiura has released the design for a Raspberry Pi Pico or Raspberry Pi Pico 2-powered do-it-yourself parametric equalizer — the RP2040 microcontroller of the former being good enough for use with audio systems of up to four channels, and the more powerful RP2350 of the latter expanding the gadget's capabilities to eight channels.
The builder's choice of Raspberry Pi Pico is joined by an I2S digital to analog converter board — a Waveshare Pico Audio, shiura recommends — and a Waveshare Pico LCD 2 display. All the hardware is assembled in a 3D-printed case, though you'll need a couple of other things to get started: a computer running a copy of the free Room EQ Wizard (REW) software and a calibrated microphone.
The idea is simple: REW is used to monitor the frequencies picked up by the microphone at different points in the room, data from which is then used to generate a custom equalizer curve. Using the buttons and display on shiura's gadget, this curve can then be programmed into the Raspberry Pi Pico and applied to the USB DAC — delivering the necessary corrections for any USB-compatible device.
The full tutorial is available on Instructables, with case STL files, source code, and pre-compiled firmware available on GitHub under an unspecified license.
