Possible Williams ADPCM Sound Board Emulation Issue

kirishima · Post by **kirishima** » 2017-12-01, 0:42:31

Specifically the games that use the YM2151, OKI MSM625 adpcm, DAC combo

This is more likely a mame issue rather than a vgm, but there could potentially be a volume balance issue between the 3 chips with that sound board with either the dac or oki being too loud and fm not loud enough.

There has been discussion about Mortal Kombat's volume balance being off but since there is no direct pcb footage, it was never really taken seriously. I ended up finding potential pcb footage of a game that should run on the same hardware setup as Mortal Kombat, NBA Jam. I say "potential" because the description says "recorded from jamma board" rather than outright confirming that it's not emulation.

https://www.youtube.com/watch?v=ogkuVQoUZ8Q

Current mame emulation sounds similar to this:

https://www.youtube.com/watch?v=uQz5fYnRQZ4

kirishima · Post by **kirishima** » 2017-12-02, 0:37:54

Just a post to apologize for the potentially misleading title. I just read it and realized how it could be perceived and changed it immediately. Also, anyone know if it's possible to embed videos here(and how) so others won't have to go to another site just to watch it?

ctr · Post by **ctr** » 2017-12-02, 8:56:49

All the current Williams/midway packs already have an extra header, so changing the volume balance won't be hard. I didn't have a real hardware recording when doing the packs so I just guessed what the balance was supposed to be.

To change the DAC volume, edit bytes 0x10f-0x110 with the desired volume. The current value is 0x8280 (shows up as 80 82 in the hex editor, this is little endian for 2.5, keep in mind bit 15 must be set), to change to 1.0 change it to 0x8100 and so on.

I don't want to go back and forth with changing values and getting feedback, so I think it's best if you figure out the best values. Please submit a fixed pack in the pack update thread in the submissions forum. Or you can just tell me the correct values and I'll update the packs.

kirishima · Post by **kirishima** » 2017-12-17, 2:14:58

Is there any way to change the fm volume? I did some playing around in mame with the williams.cpp sound driver, and in the current settings, the fm volume is set to 0.10. Changing it to 0.15 seems to better match the video's fm volume. Otherwise the setting 1.0 (80 81 ?) setting might be the correct volume.

Here are some test vgms I used for checking: https://www.dropbox.com/s/3pzfqbv10n2wj ... ms.7z?dl=1

On a side note, the mamedevs have since lowered the volume of the oki adpcm output. The fm and dac are still the at the initial settings, however, so that should probably be taken into consideration if deciding to change the volume.

UPDATE: Here are a couple recordings from the modded mame.exe with the fm volume adjusted from 0.10 to 0.15 for comparison:

nbajam: https://www.dropbox.com/s/q8cza28yxa656ul/nbaj.mp3?dl=1

mk: https://www.dropbox.com/s/z8mde4yp3voef ... o.mp3?dl=1

Edit: I forgot to mention I muted the adpcm channel in the mk recording after the "Kano" callout, so as to hear the dac and fm better since that usually what's used for music. Didn't do so with NBA jam because there no vgm for that yet afaik and to compare with the video recording.

talent · Post by **talent** » 2022-05-28, 10:44:08

Thank goodness I came across this thread.

I noticed the same volume mixing issue in the NBA Jam thread: viewtopic.php?p=14403#p14403. Will try and follow ctr's advice and if I come across any issues with editing the hex values, I'll ask for some help.

Update: Here's a recording of the "Game Start" theme from NBA Jam's Sound Board Test menu - https://anonfiles.com/jagbEak4y0/NBA_Ja ... _Start_mp3. (Was ripped with MAME to .wav and I converted it to mp3.)

Compare this to the NBA Jam "Attract & Player Setup" VGM track rip and the mixing is definitely off.