DIY spectrum analyzer is an easy project for beginners

Spectrum analysis is a technique that allows someone to observe the magnitude of different frequency ranges in a signal. The most common use case is in the world of audio engineering, as it is useful for adjusting audio output. It can, for example, show you that a particular audio signal has little amplitude in the low bands and this tells you that you need to boost the bass. If you want to try it for yourself, Sam Dartel has designed an easy-to-build DIY spectrum analyzer for beginners.

For a spectrum analyzer to work, it must be able to break down an electrical signal into a series of frequency ranges. In an audio signal, frequency is pitch. This means that higher frequency ranges correspond to higher notes in the audio. This spectrum analyzer uses an integrated circuit MSGEQ7, which is an equalizer filter, to extract seven frequency ranges from an audio signal. It outputs the peak of each band, giving a real-time readout of each band's amplitude.

There are two versions of this spectrum analyzer: one battery powered and one USB powered. Both are shields for an Arduino Nano board, which takes the output of the MSGEQ7 and uses the FastLED library to set the number of LEDs lit across seven WS2812B individually addressable RGB LED strips. Each band is a 2D display and that is sufficient for the amplitude of each band, but the color and brightness of the LEDs introduce two other possible dimensions. This spectrum analyzer uses them for different effect models.

To build this spectrum analyzer, you will need to have one of two shield PCB designs made. All components are pass-through for ease of assembly.