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  • Joined: 06 Sep 2015
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Instrument changing
Post Posted: Wed Apr 08, 2020 4:09 pm
So I've been using the Mod2PSG2 program to compose music for my Game Gear games. I was just wondering if there are any other instruments I can get that the Game Gear can play and if so, where to download them.
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  • Joined: 01 Feb 2014
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Post Posted: Tue Apr 14, 2020 3:59 pm
I'm not sure I know what you mean. The PSG sound chip doesn't have different instruments like the FM chip does. All it can do is produce square waves and noise.

Nevertheless, trackers targetting the PSG do have instrument editors, but the 'instruments' those produce are little more than volume envelopes. MOD2PSG2 is no exception, although it does let you add a bit of vibrato to your 'instrument' if desired.
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Post Posted: Wed Apr 15, 2020 4:42 pm
There is some odd tricks that involve chords, or harmonics (ie. playing two channels at the same note, an octave apart, to get an odd hybrid between a 25% Pulse Wave and a Sawtooth), but Kagesan is right - the SN76489 PSG is terribly limited as a soundchip.

There's also some trickery involving the Noise channel, but that's also quite inflexible.

I would enjoy seeing a guide written describing how various composers achieved their specific sounds. I feel like a lot of this sort of thing isn't obvious without explaining why it works - which can involve an innate understanding of how harmonics and reverb also work.
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Post Posted: Fri Apr 17, 2020 12:31 am
OK, I just thought that there might have been different types of tones (since the mod2psg2 instructions talk about different 'instruments') that the Game Gear could play, but I guess not.
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A module has 16 instruments, numbered 0 to 15.
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Post Posted: Fri Apr 17, 2020 6:02 am
- 50% square
- 6.25% square
- White noise

Those are the three different tones the PSG is capable of. Each of them has 16 volume values and 1024 frequency values. You can create different sounding instruments as a result of experimenting with volume values and frequencies.

In Mod2PSG2 editor the noise channel emulation is fine for the preset noise frequencies but messes up anything more complex. You might try different things in the editor and discard them thinking they sound bad when in reality that's not how they sound on hardware.
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Post Posted: Fri Apr 17, 2020 2:44 pm
Gamegearguy wrote
A module has 16 instruments, numbered 0 to 15.

These 'instruments' are the aforementioned volume envelopes. You can define a bunch of them, then use them at will.
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