This is a spectrum analyzer that visualizes 10 audio frequency bands. Although it might look like just another FFT ESP32 project, it is most certainly not! This design uses a PCB that I designed and build and although it involves an ESP32, it doesn't involve FFT. ( A digital way to determine what frequencies are embedded in a signal). The analysis of the input signal is actually done by 10 good old fashion opamp driven, band filters.

An ESP32 is used to host a webserver for visualization and to drive all the leds on the acrylic display.

Here are some of the specifications:

• 10 Opamp based band pass filters
• Onboard Power supply 12V input/4A to onboard 5V/3.3V
• Microphone and Line input
• Onboard multiplexor to switch between audio signals
• Onboard Analog switch to toggle between input signals
• Operating panel with 3 potmeters and 2 switches
• Onboard pre-amplifiers
• Onboard input protection against wrong polarity and over-current
• All hardware and software are open source

All building instructions are here:

https://www.instructables.com/Classic-Analog-Spectrum-Analyzer-for-Your-Desktop/

If you prefer to order a pre-assembled version of the pcb try this:

https://www.tindie.com/products/markdonners/pcb-10-channel-analog-spectrum-analyzer/

Code schematic and more here:

https://github.com/donnersm/Analog-Analyzer

Video here: https://youtu.be/J-84QGtK8YU