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AY-3-891x or YM2149 detection utility for ZX Spectrum

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We recently discovered that many AY-3-8910 soundchips that currently can be obtained, are actually YM2149 soundchips, but ‘blacktopped’ and ‘remarked’ as AY-3-8910, most probably because of a demand for the AY-3-8910.
YM2149’s are indeed pincompatible and do work just fine instead of a AY-3-8910, but sound a little different (check out this video).

If you want to check that the soundchip on e.g. your sound system is an ‘original’* AY-3-891x (-8910 / -8912 / -8913) or remarked YM2149 chip, you can use this free detection tool: https://velesoft.speccy.cz/other/aydete.zip
Big thanks to George Velesoft for this tool, and Peter Smith for the testing.

* The currently obtainable chips, mostly from China, are often blacktopped and remarked, but under the new layers of paint it might still or may not be be an original chip.
So IT CAN STILL BE SOME CLONE! We can’t tell for sure for all the chips on the market.

This applies to:

  • ZX Spectrum 128K models with integrated AY-3-8912
  • Harlequin / Nuvo / Omni with either AY-3-8912 or AY-3-8910 (later models) or ‘File’-brand clone
  • ZX-AY or other external sound add-on with e.g. AY-3-8912 or AY-3-8910

Some more background info based on our experience and the people we discussed this with:

  • AY-3-8912’s often seem to be legit, and working (we had about 2% defective ones, for which we claim a refund since these chips now cost about €7 each).
  • AY-3-8913’s seem to be fake or semi-defective since the noise generator doesn’t work with *ALL* that we tested, but these might also be some other sound chip that is pin compatible but not sound-equal, costing about €1 only.
  • AY-3-8910’s seem to be remarked YM2149’s mostly: pincompatible, fully working, but sound slightly different. Many people prefer the YM over the AY chips because of improved features, costing about €1 only.

Cheap “AY-3-8910” are actually YM2149’s

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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