Software-Emulated Amplifier: Cracking while change Volume I'm developing a software emulated analog synthesizer in the style of Euro Rack Modules. I have a problem with the volume amplifier.
Whenever I control the volume button via mouse/hand/manually rapidly (fast low and up, or fast from low to middle), I hear lots of little cracks while changing the volume. The confusing fact is, when controlling the button via automatism, like via LFO (Low-Frequency Oscillator), all is fine.
I already checked if all values are within the valid ranges (floating between -1 to 1).
Does anyone have an idea why this occurs and what I could do to avoid this?
Here's a short demonstration:
https://youtu.be/5PXcoTd32RM
I’ve heard it called popcorn noise before.  Think of the output signal as the product of the input signal and the volume signal. A discontinuity in the volume signal causes a discontinuity in the output signal. The solution is to limit the bandwidth of the volume signal.  The most common implementation I’ve seen is to limit how fast the volume can change.  Another option would be to feed the volume signal through a low pass filter.  Note that the output of an LFO is already (pretty much) band limited, which explains why you wouldn’t hear any noise in that case.