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So after picking up a JP Master System I finally had the chance to try my Monaco Master game on real hardware, and ran into an issue with the FM music. Basically its heavily distorted presumably from being too loud. I've tried a couple of different AV cables and TVs (and yes I've tried turning the volume down lol) but the issue still persists. Now I could manually edit all of the music tracks in MoonBlaster but that leads me to another issue in that I have no idea how to change the volume of the percussion! Is it even possible to do that in MoonBlaster? Similarly, does MBMLib have any way to reduce the volume of playback?

Apologies for asking multiple questions in a single post, but this issue is really bugging me and I want to get it fixed. I also noticed that a couple of other games occationally have distortion/clipping such as the Sonic 1 FM hack and Aleste. Is this normal on real hardware or is there something wrong with my system causing the output to be louder than it should be?

Oh yeah I should probably add that PSG music sounds fine across the board (both in my game and retail games)

Louis The SEGA Nerd wrote

does MBMLib have any way to reduce the volume of playback?

No. But I don't think you should get heavily distorted FM audio. It may be louder then the PSG one, or softer, but heavy distortion is not expected.

sverx wrote

Louis The SEGA Nerd wrote

does MBMLib have any way to reduce the volume of playback?

No. But I don't think you should get heavily distorted FM audio. It may be louder then the PSG one, or softer, but heavy distortion is not expected.

Ah no worries. I'll record some footage if I get chance tomorrow to demonstrate the issue. Another bizarre thing is that when recording footage I have to lower the volume level in OBS to around -40db instead of the -3db I use when recording other systems such as a Famicom or PS1.

So here's some footage from the sound test to demonstrate the issue:

For comparison purposes I also recorded some gameplay from Super Racing directly after using all of the same recording settings and the only distortion heard in that game is a bit from the start light sounds and lap completed sound:

Are you using some kind of custom instrument that does crazy things? Even then, there shouldn’t be any distortion at all. Usually, FM music actually sounds quieter than PSG, so it’s a bit worrying, that you have to turn the sound down so much.

Regarding the volume of the drums, you can change it in the drum menu (F8), for each drum individually, although those that share a channel might be affected by each other. If you want to play the same drum at different volumes, to give your drum track a little more dynamic, you can't do that. You can apply a workaround, though. Moonblaster lets you define three different drumsets. Just define identically sounding drumsets at different volumes, and instead of changing the volume in your drum track, you change the drumset.

Kagesan wrote

Are you using some kind of custom instrument that does crazy things? Even then, there shouldn’t be any distortion at all. Usually, FM music actually sounds quieter than PSG, so it’s a bit worrying, that you have to turn the sound down so much.

Regarding the volume of the drums, you can change it in the drum menu (F8), for each drum individually, although those that share a channel might be affected by each other. If you want to play the same drum at different volumes, to give your drum track a little more dynamic, you can't do that. You can apply a workaround, though. Moonblaster lets you define three different drumsets. Just define identically sounding drumsets at different volumes, and instead of changing the volume in your drum track, you change the drumset.

I'm not using any custom instruments at all! I think it might just be a case of lowering the volume of EVERYTHING which is gonna be a bit of a pain but as long as it solves the issue it'll be worth it. Ah, the joys of massively outdated trackers ey?

I’m not sure it’s an issue of the tracker. Even when having all channels at full volume at the same time, there should be no distortion, and I think it’s unlikely that you’re even doing that.

Could you try downloading my "Sunny the Mermaid Intro" from the homebrew section, and maybe the ACP test program v2 too? Those definitely play flawlessly on my setup, as does ValleyBell's Sonic FM hack.

My guess is that there’s something not quite right with the FM audio output of your system, but I know nothing about electronics, so it’s up to others trying to guess what it could be.

Louis The SEGA Nerd wrote

Another bizarre thing is that when recording footage I have to lower the volume level in OBS to around -40db instead of the -3db I use when recording other systems such as a Famicom or PS1.

-40dB is quite some attenuation.
Does this also apply to when the console is playing PSG sounds, or is it only when it's playing FM sounds?

willbritton wrote

-40dB is quite some attenuation.
Does this also apply to when the console is playing PSG sounds, or is it only when it's playing FM sounds?

I have to set it to that for both FM and PSG yeah. Honestly it's probably because my capture card is one of those really cheap easycap things that has a ton of white noise regardless of the system. It generally sounds fine on a regular TV.

Anyway, I reduced the volume of ALL of the music (both FM and PSG) by 3 clicks so the max volume of any FM instrument is 12/15. This has fixed the issue thankfully and I'll post the new .sms file in the Monaco Master thread (the update is already available on itch.io)

Monaco Master V2.91.zip (1.29 MB)

Kagesan wrote

I’m not sure it’s an issue of the tracker. Even when having all channels at full volume at the same time, there should be no distortion, and I think it’s unlikely that you’re even doing that.

Could you try downloading my "Sunny the Mermaid Intro" from the homebrew section, and maybe the ACP test program v2 too? Those definitely play flawlessly on my setup, as does ValleyBell's Sonic FM hack.

My guess is that there’s something not quite right with the FM audio output of your system, but I know nothing about electronics, so it’s up to others trying to guess what it could be.

So I just tried your sunny the mermaid intro and it sounds completely fine (it has a really cool sound might I add :D)

I discovered the same problem a while ago - here is the thread for that issue: https://www.smspower.org/forums/18086-NeedSomeFMSoundEnthusiastsJPSMSFMSoundIssue#112188.

Since then, I bought yet another JP Master System and, surprise, it still has the distortion. So, now I have two systems, both with heavy distortion on a certain FM channel. Seems like it only affects one or a small number of FM channels on the chip.

I currently run under the assumption that most (maybe all?) JP Master Systems are plagued by distortion on the FM circuit. Re-capping the system will not help.

It would be great if someone who has knowledge of these circuits could take a good look at it to determine what could be going wrong.

Author	Message
Louis The SEGA Nerd Joined: 30 Jan 2023 Posts: 56 Location: Manchester, England	FM distortion / clipping on real hardware Posted: Thu Jul 06, 2023 1:07 pm
	So after picking up a JP Master System I finally had the chance to try my Monaco Master game on real hardware, and ran into an issue with the FM music. Basically its heavily distorted presumably from being too loud. I've tried a couple of different AV cables and TVs (and yes I've tried turning the volume down lol) but the issue still persists. Now I could manually edit all of the music tracks in MoonBlaster but that leads me to another issue in that I have no idea how to change the volume of the percussion! Is it even possible to do that in MoonBlaster? Similarly, does MBMLib have any way to reduce the volume of playback? Apologies for asking multiple questions in a single post, but this issue is really bugging me and I want to get it fixed. I also noticed that a couple of other games occationally have distortion/clipping such as the Sonic 1 FM hack and Aleste. Is this normal on real hardware or is there something wrong with my system causing the output to be louder than it should be? Oh yeah I should probably add that PSG music sounds fine across the board (both in my game and retail games)

sverx Joined: 05 Sep 2013 Posts: 3941 Location: Stockholm, Sweden	Posted: Thu Jul 06, 2023 1:29 pm
	Louis The SEGA Nerd wrote does MBMLib have any way to reduce the volume of playback? No. But I don't think you should get heavily distorted FM audio. It may be louder then the PSG one, or softer, but heavy distortion is not expected.

Louis The SEGA Nerd Joined: 30 Jan 2023 Posts: 56 Location: Manchester, England	Posted: Thu Jul 06, 2023 1:39 pm
	sverx wrote Louis The SEGA Nerd wrote does MBMLib have any way to reduce the volume of playback? No. But I don't think you should get heavily distorted FM audio. It may be louder then the PSG one, or softer, but heavy distortion is not expected. Ah no worries. I'll record some footage if I get chance tomorrow to demonstrate the issue. Another bizarre thing is that when recording footage I have to lower the volume level in OBS to around -40db instead of the -3db I use when recording other systems such as a Famicom or PS1.

Louis The SEGA Nerd Joined: 30 Jan 2023 Posts: 56 Location: Manchester, England	Posted: Fri Jul 07, 2023 2:44 am
	So here's some footage from the sound test to demonstrate the issue: For comparison purposes I also recorded some gameplay from Super Racing directly after using all of the same recording settings and the only distortion heard in that game is a bit from the start light sounds and lap completed sound:

Kagesan Joined: 01 Feb 2014 Posts: 895	Posted: Fri Jul 07, 2023 5:57 am
Kagesan Joined: 01 Feb 2014 Posts: 895	Are you using some kind of custom instrument that does crazy things? Even then, there shouldn’t be any distortion at all. Usually, FM music actually sounds quieter than PSG, so it’s a bit worrying, that you have to turn the sound down so much. Regarding the volume of the drums, you can change it in the drum menu (F8), for each drum individually, although those that share a channel might be affected by each other. If you want to play the same drum at different volumes, to give your drum track a little more dynamic, you can't do that. You can apply a workaround, though. Moonblaster lets you define three different drumsets. Just define identically sounding drumsets at different volumes, and instead of changing the volume in your drum track, you change the drumset.

Louis The SEGA Nerd Joined: 30 Jan 2023 Posts: 56 Location: Manchester, England	Posted: Fri Jul 07, 2023 8:15 am
	Kagesan wrote Are you using some kind of custom instrument that does crazy things? Even then, there shouldn’t be any distortion at all. Usually, FM music actually sounds quieter than PSG, so it’s a bit worrying, that you have to turn the sound down so much. Regarding the volume of the drums, you can change it in the drum menu (F8), for each drum individually, although those that share a channel might be affected by each other. If you want to play the same drum at different volumes, to give your drum track a little more dynamic, you can't do that. You can apply a workaround, though. Moonblaster lets you define three different drumsets. Just define identically sounding drumsets at different volumes, and instead of changing the volume in your drum track, you change the drumset. I'm not using any custom instruments at all! I think it might just be a case of lowering the volume of EVERYTHING which is gonna be a bit of a pain but as long as it solves the issue it'll be worth it. Ah, the joys of massively outdated trackers ey?

Kagesan Joined: 01 Feb 2014 Posts: 895	Posted: Fri Jul 07, 2023 9:10 am
Kagesan Joined: 01 Feb 2014 Posts: 895	I’m not sure it’s an issue of the tracker. Even when having all channels at full volume at the same time, there should be no distortion, and I think it’s unlikely that you’re even doing that. Could you try downloading my "Sunny the Mermaid Intro" from the homebrew section, and maybe the ACP test program v2 too? Those definitely play flawlessly on my setup, as does ValleyBell's Sonic FM hack. My guess is that there’s something not quite right with the FM audio output of your system, but I know nothing about electronics, so it’s up to others trying to guess what it could be.

willbritton Joined: 06 Mar 2022 Posts: 697 Location: London, UK	Posted: Fri Jul 07, 2023 9:29 am
	Louis The SEGA Nerd wrote Another bizarre thing is that when recording footage I have to lower the volume level in OBS to around -40db instead of the -3db I use when recording other systems such as a Famicom or PS1. -40dB is quite some attenuation. Does this also apply to when the console is playing PSG sounds, or is it only when it's playing FM sounds?

Louis The SEGA Nerd Joined: 30 Jan 2023 Posts: 56 Location: Manchester, England	Posted: Fri Jul 07, 2023 9:45 am
	willbritton wrote -40dB is quite some attenuation. Does this also apply to when the console is playing PSG sounds, or is it only when it's playing FM sounds? I have to set it to that for both FM and PSG yeah. Honestly it's probably because my capture card is one of those really cheap easycap things that has a ton of white noise regardless of the system. It generally sounds fine on a regular TV. Anyway, I reduced the volume of ALL of the music (both FM and PSG) by 3 clicks so the max volume of any FM instrument is 12/15. This has fixed the issue thankfully and I'll post the new .sms file in the Monaco Master thread (the update is already available on itch.io) Monaco Master V2.91.zip (1.29 MB)

Louis The SEGA Nerd Joined: 30 Jan 2023 Posts: 56 Location: Manchester, England	Posted: Sat Jul 08, 2023 7:47 am
	Kagesan wrote I’m not sure it’s an issue of the tracker. Even when having all channels at full volume at the same time, there should be no distortion, and I think it’s unlikely that you’re even doing that. Could you try downloading my "Sunny the Mermaid Intro" from the homebrew section, and maybe the ACP test program v2 too? Those definitely play flawlessly on my setup, as does ValleyBell's Sonic FM hack. My guess is that there’s something not quite right with the FM audio output of your system, but I know nothing about electronics, so it’s up to others trying to guess what it could be. So I just tried your sunny the mermaid intro and it sounds completely fine (it has a really cool sound might I add :D)

Glimlocker Joined: 25 Mar 2020 Posts: 20	Posted: Sat Jul 29, 2023 7:04 pm
Glimlocker Joined: 25 Mar 2020 Posts: 20	I discovered the same problem a while ago - here is the thread for that issue: https://www.smspower.org/forums/18086-NeedSomeFMSoundEnthusiastsJPSMSFMSoundIssue#112188. Since then, I bought yet another JP Master System and, surprise, it still has the distortion. So, now I have two systems, both with heavy distortion on a certain FM channel. Seems like it only affects one or a small number of FM channels on the chip. I currently run under the assumption that most (maybe all?) JP Master Systems are plagued by distortion on the FM circuit. Re-capping the system will not help. It would be great if someone who has knowledge of these circuits could take a good look at it to determine what could be going wrong.

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