2 of 2 found this helpful:

Everyone knows what this thing is for - and it works as advertised. If you want a spectrum analyzer without doing all the fancy math in-code, get this thing.

Beware, however, of noise and input sensitivity. I had this champ hooked up to an Arduino with the BOB-09964 microphone and COM-12999 addressable RGB LEDs.

First, the LEDs turned on and permanently burned my retinas. Once I could see again and adjusted the brightness, the "output" was still all over the place. This is due to the sensitivity of the microphone - the chip was just doing its thing. So taking the raw-input from the MSGEQ7 and subtracting 127 eliminated most of the noise. Except for the 63Hz band.

I fought this for hours. Replaced the chip three times, turned off my TV, radio, fans, everything I could think of, but the 63Hz band kept flickering even in the quietest room I could make it.

While sitting there, cooling off from frustration, I hear the soft click of my refrigerator's compressor turning off - which was in the other room. The 63Hz band light stopped flickering.

Moral of the story - just because you can't hear it that well, doesn't mean your device will have the same problem.