i don't know the chips well in the two newer consoles this initial version comes with, but certainly the infamous SID/MOS 6581 has numerous variations. People

i don't know the chips well in the two newer consoles this initial version comes with, but certainly the infamous SID/MOS 6581 has numerous variations. People have been slowly collecting recordings of and characterizing them. There are 2-3 main revs of the chip, plus variations within a batch, from batch-to-batch, and also the two filter capacitors on peoples' motherboards vary. Remember that note only was MOS/Commodore innovating in the logic and multimedia design of the chips, but they also invented the PMOS process IIRC and were steadily developing it. Note only does that result in variations in cutoff/center frequency of filters, but when the caps overlap in value, for example, a tighter resonance is achieved. Many SID tunes are known to have been overfitted to the composer's machines, and some people even evince the characteristics of the composers' machines and configure their emulators to sound like the composer's computer.