From what I understand, OPL3 has a few extra registers/channels over OPL2, but not very many games supported them for some reason.

So are you saying that a game which was designed for only OPL2 will sound the same on OPL3? I think there's more to it than registers. From what I've been reading, the sound is different.

The OPL3 is intended to be fully backwards-compatible to the OPL2, which means an OPL2 app should sound exactly the same on an OPL3. If you don't use the new features, it behaves like an OPL2.

The OPL3 was not widely supported before 1992 because few sound cards had it (first appeared on later SB Pro revisions, I think). Sid Meier's Civilization for example had a special driver for OPL3 cards added at the last moment (or probably as a separate download, don't recall exactly), and indeed, the music sounds more richly with it.

If the actual silicon produced different sounds due to analog side-effects is unknown to me, but that is hardly intentional.

What track are you testing with? Maybe it is programmed/composed for just OPL2?

It's the Tenebrae music from Ultima 8, FWIW. Like I said, from what I'm told, it shouldn't make a difference which chipset the music was programmed for. Someone who seems to know what he's talking about says that even though OPL3 is backwards compatible, the sound isn't the same.

This page has Microsoft's take on the differences between OPL2 and OPL3:

http://support.microsoft.com/kb/89877

They should say "stereo" (with the quotes), as it isn't true stereo. Anyway, I can't find anything suggesting OPL3 sounds any better than OPL2 if the enhanced capabilities aren't being directly used.

Angus wrote:

It's the Tenebrae music from Ultima 8, FWIW. Like I said, from what I'm told, it shouldn't make a difference which chipset the music was programmed for. Someone who seems to know what he's talking about says that even though OPL3 is backwards compatible, the sound isn't the same.

"seems to know" seem the right words here. I have never heard anyone claiming this, nor have I heard it myself. Both OPL2 and OPL3 produce a digital output, and I'd be very surprised if the OPL3 in OPL2 emulation mode (or, for that matter, in native mode using the same 'instruments') produce a different digital output. I think the person that 'seems to know' there's a difference is confused by either the fact that the digital output must be converted to ananlogue by a D/A converter, and hence the actual sound depends on the type of D/A converter used, or (more likely) he confuses the real OPL3 with the not-so-good emulation present in the later sound blaster derivatives (like AWE64 and Live). See also this thread: Authenticity of AdLib sound

JAL

differences between OPL2 and OPL3 not documented in Yamaha datahasheets:
- sinus table is a little different: the negative part is off by one...
- in order to enable selection of four different waveforms on OPL2
one must set bit 5 in register 0x01(test).
on OPL3 this bit is ignored and 4-waveform select works *always*.
(Don't confuse this with OPL3's 8-waveform select.)
- Envelope Generator: all 15 x rates take zero time on OPL3
(on OPL2 15 0 and 15 1 rates take some time while 15 2 and 15 3 rates
take zero time)

- channel calculations: output of operator 1 is in perfect sync with
output of operator 2 on OPL3; on OPL and OPL2 output of operator 1
is always delayed by one sample compared to output of operator 2

differences between OPL2 and OPL3 shown in datasheets:
- YMF262 does not support CSM mode

Jal:

Did you notice who started Authenticity of AdLib sound? Needless to say, I've been through it.
The web site where I discovered Mr Seem To Know is http://www.yvan256.net/soundcards/. He doesn't discuss the differences between OPL2 and OPL3 on that page, but it does explain how he got his name.

Harekiet:

So what are you saying? The chips are different? Significantly different? Starkly different? Different in about 1 in 1,000,000 tones? Different only to people with very very sharp ears?

I have no idea how that will affect music, probably only in very specific cases and even then the difference might be neglible, will just have to find some clear examples probably. But i guess if there really were big differences people with newer cards that had opl3 chips would have complained more if their old stuff didn't sound the same.

Angus wrote:

Did you notice who started Authenticity of AdLib sound? Needless to say, I've been through it.

Not until now I didn't 😀.

The web site where I discovered Mr Seem To Know is http://www.yvan256.net/soundcards/. He doesn't discuss the differences between OPL2 and OPL3 on that page, but it does explain how he got his name.

Yeah, I know that page. He has a picture of the same AdLib card I have now, but it's different from the one I once owned (that was a merrier shade of green).

JAL

opl3 can do more notes that opl2, so if the music has great polyphony the chip would not cut some music

=zum= wrote:

opl3 can do more notes that opl2, so if the music has great polyphony the chip would not cut some music

Cutting music is entirely handled in software, you make it sounds as if it's handled in hardware. Presumably you mean MIDI emulation through the AdLib card. In that case you are right, as long as 2-operator mode is chosen on the OPL3.

JAL