[arcelx]

I’d really love to know how this main detuned bell sound that plays during the majority of the song can be synthesized or recreated.

[Mark Luljak]

It doesn’t actually sound like a bell to me. Not enough ring, even filtered, and the attack sounds wrong. Sounds more like a flute.

Regardless of the basic nature of the patch, there are three things you’d need to do:

1) Create the basic sound.

2) Put EQ on it (notably LPF/HCF, although you may need to season to taste.

3) Put a (probably modulated, so it doesn’t get annoyingly repetitive, so I’d use an LFO) pitch modulation on it. Make that modulation bipolar, and center it evenly around the target of no pitch change. For example, +50/-50 cents. If you need to get even more irregular, you could use a noise waveform for the LFO, if your LFO supports it. Barring that, modulate the LFO with another LFO. Usually once you get two or three LFOs modulating each other, it feels largely random.