The Hearts of the Super Nintendo (2024)
fabiensanglard.net
fabiensanglard.net
Was it that important to have an exactly 32000 Hz sample rate? They could have used a divide-by-21 to get within 0.2%, which would have been more accurate than that ceramic resonator. Or keep the existing divider and run resample all the audio to 27.97 KHz, which IMO would have been acceptable.
Or someone just really cared about sound quality (see also: the metal box).
Another bit of evidence for that: While they merged all the audio chips into a single S-APU chip, and both PPUs and the CPU into the 1CHIP, they never went the final step of merging the APU, PPU and CPU into a single chip. And they never shrunk the PCB to move the two chips closer.
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My other theory is that if the audio clock was derived from the video clock, then it would have a different sample rate on NSTC and PAL consoles; By giving it an independent crystal, they can make sure both models have the same audio sample rate.
It's probably a combination of many of these small factors prevented them from ever going to the effort of trying to make it work from a single crystal.
Recent related repost: The Super Nintendo Cartridges (2024) (171 points, 30 comments) https://news.ycombinator.com/item?id=47906161
..At it's time (548 points, 153 comments) https://news.ycombinator.com/item?id=40111274