Is there anyone here who might know about spectrum analysers?

Post-Master_Sodium · August 8, 2017, 7:36am

I’m building an LED covered jacket, which I want to function as a spectrum analyser. I will be using ws2812b strips for the LEDs, and a teensy 3.2 to control it all.

Naturally, the PJRCSpectrumAnalyser example is the first place I look for code to start with

github.com

FastLED/FastLED/blob/master/examples/Ports/PJRCSpectrumAnalyzer/PJRCSpectrumAnalyzer.ino

// LED Audio Spectrum Analyzer Display
//
// Creates an impressive LED light show to music input
//   using Teensy 3.1 with the OctoWS2811 adaptor board
//   http://www.pjrc.com/store/teensy31.html
//   http://www.pjrc.com/store/octo28_adaptor.html
//
// Line Level Audio Input connects to analog pin A3
//   Recommended input circuit:
//   http://www.pjrc.com/teensy/gui/?info=AudioInputAnalog
//
// This example code is in the public domain.

#define USE_OCTOWS2811
#include <OctoWS2811.h>
#include <FastLED.h>
#include <Audio.h>
#include <Wire.h>
#include <SD.h>
#include <SPI.h>

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I was wondering a couple things

Can I get the same effect without using a smartmatrix? (Or any pre built matrix display) I plan on using strips, so the frequency bands can be dispersed all over my jacket.

Can I accomplish this effect without the octows2811 adapter? My “matrix” will be 6 pixels tall x 18 pixels wide (18 strips of 6 LEDs each), so 108 pixels total.

Thanks for your assistance!

Ken_White · August 8, 2017, 1:19pm

@Post-Master_Sodium - Use the Search Community box on the left of this webpage with the term: spectrum. Also, search with the name: Matt Camp. Matt Camp has a great top hat spectrum analyzer in which he shares his code. Also search with: spectrum deamcoat. Robert Atkins shares the code for his amazing dreamcoat with spectrum analyzer. These searches and projects should be helpful to you.

Franck_Marcotte · August 8, 2017, 2:45pm

A simple tutorial that got me started : https://learn.adafruit.com/fft-fun-with-fourier-transforms/spectrum-analyzer

It uses a Teensy 3.2 and a microphone, very easy to wire and get started.

Also, where do you plan on using your jacket? I’ve had terrific success with sound reactive projects in small setups in the 33-50 decibel range, but I’ve had trouble getting good results in festivals over 70+ decibels. It’s much harder to tune. It seems like all the frequencies overload each other or something. Just so you know when you do your tests.

Post-Master_Sodium · August 8, 2017, 3:42pm

Thanks @Ken_White , I was using the android app, so I didn’t have a search function, but logging in through the web works, I will definitely look those up!

@Franck_Marcotte I hope to have it usable for oregon eclipse (music festival). I do know the fft tutorial you posted. I was planning on using that first, then working it out so each strip is a frequency band, and looks more like the common specrum analyser.

I’m not sure it will work as good as I hope, but I’m going to add a potentiometer to adjust the dB range, so I can (hopefully) fine tune it to where I’m at. We’ll see how it goes though, lol.

matt_p · August 10, 2017, 7:23am

Hello @Post-Master_Sodium

You can use Garret Mace’s tool to generate a mapping function for just about any possible LED strip combination (https://macetech.github.io/FastLED-XY-Map-Generator/).

Post-Master_Sodium · August 10, 2017, 7:26am

Thanks @matt_p , that’s a very nice tool to have in the arsenal! I’m sure I’ll get much use out of that!

Cristian_Martinez · August 10, 2017, 10:52am

Let me know how it turns out

Post-Master_Sodium · August 10, 2017, 2:02pm

Sure will @Cristian_Martinez