10 LEDs driven unfiltered to audio signal. LED driver is an LM3915 with a LM324 op amp for signal amplification.
I plan on eventually hooking up 10-20 banks of these with bandpass filters to make a spectrograph. I'm also thinking about having several modes, including summing the left/right speaker signals and maybe even displaying the difference.
![](https://i.ytimg.com/vi/Edup953M7SE/mqdefault.jpg)