Yes, real Yamaha OPL3 can be more speed sensitive than clones. And oldest games made for AdLib may not have any delays between writes so even a fast 486 is too fast for them. You can try Midito to add delays . But P2 is too fast for many games even if you get OPL working.

Riikcakirds wrote on 2022-06-19, 17:41:

Is this just a drawback of any card that use a genuine OPL3 v creative CQM chips (which appear not to be speed sensitive).

I have only used my Vibra (with real OPL3) on a Pentium MMX 166 and it had no speed issues there.

However, I did test a (PCI) Yamaha YMF744 on an AthlonXP 1700+ system at full speed, and it worked perfectly. No issues whatsoever with FM synthesis, even on older games from the early 90s.

Joseph_Joestar wrote on 2022-06-19, 19:43:

Riikcakirds wrote on 2022-06-19, 17:41:

Is this just a drawback of any card that use a genuine OPL3 v creative CQM chips (which appear not to be speed sensitive).

I have only used my Vibra (with real OPL3) on a Pentium MMX 166 and it had no speed issues there.

However, I did test a (PCI) Yamaha YMF744 on an AthlonXP 1700+ system at full speed, and it worked perfectly. No issues whatsoever with FM synthesis, even on older games from the early 90s.

What model vibra did you have? So it appears it's not opl3 v cqm but card related. I had heard about this speed sensitive problem years ago but thought it only affected sbpro and very early models (1992) of the sb16. Still, i'm a bit surprised a newer card like the ct2800 has this problem.

Riikcakirds wrote on 2022-06-19, 17:41:

Is this just a drawback of any card that use a genuine OPL3 v creative CQM chips (which appear not to be speed sensitive). Seems a bit odd when there is only 1 year release difference between a CT2800 vs a CT2960.

Yes, OPL3-compatible clones (CQM, ESFM, etc) responds to commands much faster than the real thing.

Riikcakirds wrote on 2022-06-19, 21:29:

I had heard about this speed sensitive problem years ago but thought it only affected sbpro and very early models (1992) of the sb16. Still, i'm a bit surprised a newer card like the ct2800 has this problem.

Early Sound Blaster cards (except SBPro2) used real OPL2 chips, which was even more speed sensitive than OPL3. In addition to this, the DSP was also speed sensitive unlike the SB16 and later Creative ISA sound cards.

Riikcakirds wrote on 2022-06-19, 21:29:

What model vibra did you have?

I have one of those less common SoundForte Vibra varieties. It works fine with the latest SBBASIC.EXE driver from Creative's website.

BTW, check if your BIOS has an option called 16-bit I/O Recovery Time. Sometimes, setting this delay to a higher value can help with speed sensitive sound cards.

Joseph_Joestar wrote on 2022-06-20, 06:29:

BTW, check if your BIOS has an option called 16-bit I/O Recovery Time. Sometimes, setting this delay to a higher value can help with speed sensitive sound cards.

The OP should be looking for the 8-bit I/O Recovery Time option instead, that one actually helps with sound cards having a real OPL3 chip.

Gmlb256 wrote on 2022-06-20, 13:31:

The OP should be looking for the 8-bit I/O Recovery Time option instead, that one actually helps with sound cards having a real OPL3 chip.

Hm, I thought that was for 8-bit ISA sound cards (e.g. SB 2.0), but you might be right.

It won't hurt to check both options and see if either of them helps.