ihatemornings
Active member
I’m working on a drum machine where the Teensy is triggering analog drum circuits, then the audio is fed into the Teensy (audio board line in) for processing. The drums with big transients are distorting.
I simplified the audio code to route the input directly to the output, and recorded the audio at line in and line out (input top, output bottom):
The audio input is coming from a TL072 op amp connected directly to the line in pin on the audio board, and the transients measure around 0.2V peak to peak (I reduced the gain a lot to see if that made a difference, but it doesn’t). The op amp has +9V/-9V supply, biased to the Teensy’s audio ground.
I’ve tried adding a series resistor between the op amp and the Teensy with a capacitor to ground from the line in pin (tried 100ohm/47pF and 1k/4.7pF). It changed the sound slightly, but the distortion is still there.
I feel like I need to add more protection against the peak current of the transients, but not sure how! Any ideas?
I simplified the audio code to route the input directly to the output, and recorded the audio at line in and line out (input top, output bottom):
The audio input is coming from a TL072 op amp connected directly to the line in pin on the audio board, and the transients measure around 0.2V peak to peak (I reduced the gain a lot to see if that made a difference, but it doesn’t). The op amp has +9V/-9V supply, biased to the Teensy’s audio ground.
I’ve tried adding a series resistor between the op amp and the Teensy with a capacitor to ground from the line in pin (tried 100ohm/47pF and 1k/4.7pF). It changed the sound slightly, but the distortion is still there.
I feel like I need to add more protection against the peak current of the transients, but not sure how! Any ideas?