@nkogliaz Actually I've had a solution to the problem for a while by using Live's EQ to cut out the high pitches. So really this thread is just trying to figure out why there are there and alternatives other than that. It'd be nice, for instance, to have a portable solution. On that note, I am curious why a real analog low-pass filter wouldn't work? It cuts frequencies above a threshold, no? I know there is a roll-off going on there but it should hit 0 or close to it by the time it gets to the high pitches I'm trying to filter out?
"Filter" is a loaded term because I wasn't thinking of using an actual low-pass filter, with resonance and all that. Really just a regular low-pass, similar to turning down a the treble knob on a mixer. Feel free to correct me here, but using some large input capacitors along the audio chain would basically do what I would want?
What I can hear, though, is some constant high pitched bus whine, and also some lower frequency zipping noise when using an envelope. The latter noise has some high frequency content, too, which is very obvious and quite annoying. Maybe this is what you are hearing?
I'm definitely hearing high pitched aliasing when playing notes off the squares. I only hear it when actively playing something. The GameBoy does have a high pitched whine in some cases, but that seems to be different from what I am hearing. This sounds like jingling your keys on your keychain, just at a much higher pitch.