Dual Detuned SID (Arkanoid, direct capture)
A direct capture of an experiment I wanted to try. What happens when two SIDs are put into a Commodore 64, but with one running off its own clock? The expectation was the SIDs would play slightly detuned from each other, and that's exactly what happened. It can be used in mono to make the sound thicker (as shown here) or in stereo to give a stereo separation effect.
The music starts at 1:16. Sorry for it being in monochrome, I'm afraid my VIC-II isn't very well. My joystick didn't want to work either so it took me a bit to start the game.
The crystal oscillator runs at 1MHz. My PAL Commodore 64 is clocked at 0.98MHz. This is approximately a 2% increase so all sounds will have a corresponding pitch shift. A variable oscillator could be used instead of a crystal oscillator, which would give a pitch bend, fifth, octave, or any other interval effect depending on how it's used.