I'm trying to locate the source of this noise. As soon as I put a small signal like low freq on this output, it is gone. it is only there with no input signal. I programmed a volume slider before the output and it's still there.
first I thought it was limit cycles of the cross-over filter and I changed it to double precision. both peaks are 116 Hz apart and centered at at 19848 hz. my xtal clock is 12.288 Mhz. it's down in the noise, and not audible, but i'd like to find the root cause of it.
my initial thought go towards limit cycles of the DACs, lack of dithering ..
comments welcome !