I checked the datasheet for YMF704C-S and it says it is "register compatible with OPL3"... i dont know what it means though 😀

But as you only can control it with MIDI (it is a waveblaster card after all) so don't i think FM is used at all, maybe could you please record some examples from that card?

It seems "pin 29" goes to the DAC so it is mixed FM/PCM signal, it could be that some of the synth sounds in GM standard is actually played with the FM synthesis of the YMF704? maybe "synthbass"?

There are two variants of the OPL4 chip, you are referring to the one with the internal ROM.

OPL4/YMF278 - FM+Midi chip with a max of 4MB addressing space. 100-pin SQFP.
OPL4/YMF704C - as YMF278 with 1MB ROM, MPU-401 interface, GM, 24 Voices.
"contains the same sample set as the stand alone ROM which was certified by Fat Labs" (GM sound compatibility)

There are soundcards that use an YMF278 for both the general midi and FM music options. Such as the Audiotrix Pro: When used for FM it acts like a OPL3. I have not yet seen an YMF704C used in that way. Probably because at the time of its introduction most main soundcard chipsets already had their own intergrated FM solution. When the YMF704C is on a midi daughterboard it only has one midi data pin in the 26 pin connector. That connector is unsuitable for communicating FM music data.

The chip should have seperate pins for the FM part, which are left unconnected on midi daughterboards. but I have to check to make sure which ones.

Also, considering the soundcard already has an FM part, it is already connected to it.
At best you need to cut traces and solder several wire bypasses to reroute the FM to somewhere else.

I see, i also wondered why are there so little leads out of the micro chip.

How do you think one would one realize an OPL3 function/out from the chip?

Lacking time here. It is a Yamaha part, you can probably google for a datasheet that says it all.

Well, no problem in getting all OPL IO lines, but how to make something as an Turtle Beach Pinnacle reproduce OPL sounds?
Or even better, SW1000XG (card that has the most crystal clear sound i ever heard).
Or should i just get Miro Sound PCM1 PRO 😀

The professional line of Turtle Beach ISA cards was never game compatible, the SW1000XG is a PCI card that is also not aimed at gamers. If you want a game SB Pro / Adlib interface, you need pair them with a suitable soundcard.

Doesn't matter, if it can playback opl3 when requested its good for me.
I want to use it for AdLib tracker any way. I have OPL3/2 cards.

Stojke wrote:

Doesn't matter, if it can playback opl3 when requested its good for me.
I want to use it for AdLib tracker any way. I have OPL3/2 cards.

Why dont you try to plug the addon, init the turtle beach, disable it's soundblaster parts, delete the "blaster" from the set environment and try your software to detect the chip as an adlib chip at port 388h. Not sure you can do this thru a daughter board, you tell me.

Daughterboards are only accessed through MIDI interface so it will never be Adlib compatible FM interface.

Another story is if it is able to receive some sysex commands to control the FM part directly, but it won't be very fast. I know I can control my external Korg module into some kind of FM-alike tone generating mode.