05849: sg1000m3, smsj, sms1krfm: FM sound volume much lower than PSG's

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
05849	Sound	Minor	Always	Feb 16, 2015, 17:58	Jan 26, 2023, 05:46

Tester	enik	View Status	Public	Platform	MESS (Official Binary)
Assigned To		Resolution	Open	OS	Windows XP
Status [?]	Acknowledged			Driver	sega/sms.cpp
Version	0.158	Fixed in Version		Build	I686
		Fixed in Git Commit		Github Pull Request #

Summary	05849: sg1000m3, smsj, sms1krfm: FM sound volume much lower than PSG's
Description	The volume of the FM sound, generated by the YM2413 chip, is much lower than volume of the PSG sound, generated by the SN76489 PSG chip. On real hardware, FM volume seems to be a bit lower than PSG's, IMO. Official games in general support only one chip even when the two chips are available, so the user may adjust the volume at OS/hardware level as a workaround, but a correct sound balance becomes important for homebrew hacks like the one produced by ValleyBell, that changed the Sonic 1 ROM to add FM music and use PSG for sound effects.
Steps To Reproduce	Play a game that supports FM sound (when available) on a driver that only supports PSG sound (like sms1) and play again the same game on a driver that also supports FM sound (like smsj). Compare the volume of both emulated sound chips with the following video, that is a comparison of the PSG sound and FM sound of a modded Brazilian sms1 console with the FM sound of a Japanese sms console:
Additional Information	These are the relevant lines that set the sound balance in the current src/mess/drivers/sms.c file: static MACHINE_CONFIG_START( sms_ntsc_base, sms_state ) (...) /* sound hardware / MCFG_SPEAKER_STANDARD_MONO("mono") MCFG_SOUND_ADD("segapsg", SEGAPSG, XTAL_53_693175MHz/15) MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 1.00) (...) MACHINE_CONFIG_END static MACHINE_CONFIG_DERIVED( sms1_ntsc, sms_ntsc_base ) (...) MACHINE_CONFIG_END static MACHINE_CONFIG_DERIVED( sms1_kr, sms1_ntsc ) (...) MACHINE_CONFIG_END static MACHINE_CONFIG_DERIVED( sms1_krfm, sms1_kr ) MCFG_SOUND_ADD("ym2413", YM2413, XTAL_53_693175MHz/15) MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 1.00) MACHINE_CONFIG_END For comparison, these are the lines that set the sound balance for Sega Mega Drive, that has the same PSG chip, but with another Yamaha chip variant: File src/mame/machine/megadriv.c: MACHINE_CONFIG_FRAGMENT( md_ntsc ) (...) / sound hardware / MCFG_SPEAKER_STANDARD_STEREO("lspeaker", "rspeaker") MCFG_SOUND_ADD("ymsnd", YM2612, MASTER_CLOCK_NTSC/7) / 7.67 MHz / MCFG_SOUND_ROUTE(0, "lspeaker", 0.50) MCFG_SOUND_ROUTE(1, "rspeaker", 0.50) / sound hardware / MCFG_SOUND_ADD("snsnd", SEGAPSG, MASTER_CLOCK_NTSC/15) MCFG_SOUND_ROUTE(ALL_OUTPUTS, "lspeaker", 0.25) / 3.58 MHz / MCFG_SOUND_ROUTE(ALL_OUTPUTS, "rspeaker",0.25) / 3.58 MHz */ MACHINE_CONFIG_END
Github Commit

Flags
Regression Version
Affected Sets / Systems	sg1000m3, smsj, sms1krfm

Attached Files

No.11469 enik Tester Feb 19, 2015, 20:41	The Sega System E is a more direct derivative of the Master System, and the newly added code to support FM sound on MAME's fantzn2 driver sets the sound balance as: MCFG_SPEAKER_STANDARD_MONO("mono") MCFG_SOUND_ADD("sn1", SEGAPSG, XTAL_10_738635MHz/3) MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 0.70) MCFG_SOUND_ADD("sn2", SEGAPSG, XTAL_10_738635MHz/3) MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 0.70) MCFG_SOUND_ADD("ym2", YM2413, XTAL_10_738635MHz/2) MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 2.00)
No.11678 enik Tester May 25, 2015, 02:33	The patch to add FM support for the Sega System E driver was invalidated because the hardware doesn't have that support. As stated before, most ROMs with code for the FM chip just play FM sound when the hardware has support, else just play PSG sound. Most of them don't make use of both sound chips. For the record, these are the exceptions: - instructional screen of the Japanese SMS BIOS; - games with FM sound that plays sampled audio, because it requires the PSG (After Burner, Alex Kidd: The Lost Stars, Alien Syndrome, Altered Beast, California Games, Captain Silver, Space Harrier 3-D, some sports games, etc); - the Sonic 1 ROM hacked by ValleyBell to include FM together with PSG effects; - maybe future homebrew projects. I tried to fix the sound balance of the SMS drivers using videos found on the web as reference, but didn't come to a conclusion because haven't found a reliable source. I was looking for good quality videos recorded directly from original/official hardware and have PSG and FM sound played in separated moments, but with same capture settings, as input volume, without any sound effect applied. Videos of any game with FM sound that also plays sampled audio are good examples, as FM and PSG aren't played at same time. The preferred hardware is the Japanese SMS, because it has the FM chip built in, what avoid loss of gain due to additional connection of the FM unit. By using the comparisons I performed, with the FM volume kept to 1.00 on MESS, the PSG volume seems to be more faithful when set to 0.25 or 0.30, sometimes even 0.35, depending of the video sample. What also affect the comparisons are differences in the sound output that seems to be caused by inaccuracies of the YM2413 chip emulation.
No.21044 newiln2 Tester Jan 26, 2023, 05:46	The sound balance is reasonably close in 0.251 when the PSG volume is set to 0.35 as enik suggested, but the Japanese BIOS' rendition of the Space Harrier theme still sounds slightly off, almost as if certain channels were cutting out. This is the recording I've been using as reference: