Interfacing 3V3 signals to 5V chips.

I have built a Teensy 3.2 circuit to replace the rather crappy "Sound-To-Light" circuit built into my DMX Stage Lighting Controller. There's a thread all about in the forum Analog & Mixed-Signal Design, called "LM358 circuit help needed"

I am outputting a digital pin (3V3 High) on my Teensy, going low on the beats for 5mS, which better than replicates what the original analog circuit...

Interfacing 3V3 signals to 5V chips.