Recently we developed a new version of the ZX-AY that will carry a AY-3-8910 instead of the AY-3-8912 chip.
Reason for that is that the -8910 chips is a lot less expensive than the -8912 variant (which costs about 7x more).
When testing the prototypes with the -8910 chip, we discovered sound differences.
It turns out now, after some investigation (thanks to George Velesoft, Peter Smith and others) that these cheap “AY-3-8910” chips, are actually remarked YM2149 sound chips.
You can hear some differences between these ‘fake’ (they are good working YM2149’s, of which some say that those have some benefits over the AY-3-8910) in this video:
Disclaimer: I can’t say for sure that -ALL- AY-3-8910 chips from China are actually YM2149’s.
Maybe both types (AY-3-8910 and YM2149) are mixed and remarked as AY-3-8910’s.
Blacktopping and remarking is a commonly known practice in China.
We have several sources of proof for these chips being YM2149’s.
One is a test tool that clearly detects the chip as YM2149:
Another test we did is measuring / probing the audio output levels:
– An AY-chip should have a DC bias of about 0.2V.
– The YM2149 chips sits at about 2V.
Our test showed the “AY-3-8910” sitting at 2V:
So if you’re here because you’ve been investigating the same, here’s your answer 😉
The differences between AY-891x and YM2149 are described here: https://maidavale.org/blog/ay-ym-differences