Buzz on null sound stream (F32)

commi

Member
I hope this is the correct place to post this.
I found a strange situation with the OpenAudio F32, where a null sound stream still produces a low continuous buzz from the amplifier connected to the teensy (4.1+ teensy audio).

My setup:
I’ve (with an AI help) updated the fade filter to fit to the F32 audio.
I connect the Teensy to a big guitar amplifier using its high gain input.
I made a simple code to make sure that the fade in/out works.
I found that when the fade out input is >150 ms, the constant sin wave goes to 0 and there is no sound from the amplifier.
But for some strange reason, that I cannot understand, when the fade out is 30ms, there is a constant buzz from the amplifier! I’ve added a peak filter after the fade, and I see that the exit from the fade is 0, but still there is a low noise from the amplifier!

As I only have one Teensy I don’t know if it’s some issue with my hardware or some issue with the Teensy.

The process to duplicate this:
  • Run my code. A constant sin would be sound.
  • Type “2” in the serial monitor input line. A 3000ms fade out would start. At the end no sound is heard.
  • Type “1” to get a fade in and the sine sound back on.
  • Type “w” for 30ms fade out. The sine sound get lower, but a small buzz continues until you shut the Teensy off.
    the peak print out says that there is no input to the OutI2S1

Could you duplicate this issue?
 

Attachments

  • effect_fade_f32.cpp
    3.5 KB · Views: 56
  • effect_fade_f32.h
    2.4 KB · Views: 55
  • Fade_Test.ino
    1.8 KB · Views: 50
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