Cheap “AY-3-8910” are actually YM2149’s
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
Ben
My guess is that if they were in short supply of 8910s then they’d use an equivalent sound chip. Also if they were being pressured to keep the cost down then they’d go with cheaper chip. 10 if a$=”supplier” and b$=”available8910s” then goto 20
20 if b$<=a$ then goto 30
30 a$ supplies equivalent chip
Proper YM2149 chips (and the related family of similar sound chips) were manufactured by or on behalf of Yamaha. The Atari ST range uses a Yamaha YM2149F. In many respects the Yamaha version is a bit better.
The manufacturer that developed and produced the AY-3-8910 range of sound chips was bought my Microchip a long time ago. Not long after, production of these chips was discontinued. So there are no new AY-3-8910, no new AY-3-8912 or any other new chips in the same range.
On trading sites, any hard to get chips are often cleaned up ‘pulls’ taken from old equipment. They are reworked to clean up and re-tin the pins. The old markings are either cleaned off, sanded off or painted over. Then new screen printed markings are applied, often to give the impression that they are new chips. Never mind that they have been out of production for many, many years (in some cases over twenty years).
There is no guarantee that what you get will even be a working chip. Some EEPROM chips have been found to be un-programmable and some so called new CMOS Z80 and CMOS 65C02 processors have found to be slower older NMOS processors!
So buyer beware!
Mark