Even though no one responded to my last post, I hope someone knows something here.

Basically I just wanted to know what the sound limitations of the GBA are and I'm just talking about the (Direct Sound) channels for the most part but in some areas channels 1 through 4 might get mentioned.

Question 1 (this might be the easiest question)
Are the Direct Sound channels considered to be sample channels?

Question 2
What determines the amount of samples that can be played at a single time?

Question 3
What determines the amount of MIDI tracks can be played at a single time?

Question 4
When a sound effect plays why do only certain instruments cut out and not others?

Question 5
What does the note off with Noise do in the Sappy Instrument editor (cause it doesn't seem to do anything when I turn it on or off.)

Thanks in advance for anyone who responds here

London, UK

There might be some useful titbits in here/he might be a good person to try and talk to?

London, UK

also; … -in-sappy/


Last edited by Duck (Apr 22, 2020 11:08 am)

London, UK

but I think the answers to 1 is "yes" and 2 is "there are two channels", so two mono or one stereo?
You could of course combine samples to have them play as one sound.

London, UK

edit - this was not the answer!

Last edited by Duck (Apr 22, 2020 1:46 pm)

Bratislava, Slovakia … 20765.html

Here is something, btw why you are so interested in GBA? I have my GBA almost 20 years (since 2001) but i don't use it at all, maybe only once i inserted LSDj cartridge to hear differences from original DMG-01.


There are two channels of digital audio. You can use them one-shot to play two samples at a time or you can play continuous stereo sound and do everything in software. In that case, the number of samples, synth voices, effects etc is limited only by cpu power and your programming skills.


What do you mean by CPU power, I thought the samples were controlled via software so their shouldn't be a limit to the amount of samples that could be played at one time. And to answer your question Martin_demsky my fascination came with the difference in sound hardware between the SNES and GBA; originally I thought the GBA had 6 sample channels and that was it, but when I found out that 4 of those channels were legacy channels and the other two were sample-ish channels I was surprised and confused because up till that point I had been working on NES and SNES music and each sound channel could only play one note/sound at a time. That, and trying to find information that's useful and not over my head has sort of fueled my curiosity do to the lack of available information that I can understand without knowing arm assembly.

Last edited by biolizardshadow (Apr 24, 2020 5:09 am)

Bratislava, Slovakia

Aha, for example our team Cypronia back in time started that realtime strategy Command & Destroy on GBA, but was finished later as DS title, in the beginning coder asked me to compose ordinary 4-channel mods (respectively converted to s3m). If you read that northern sounds article, then you will know that Factor 5 company released MusyX editor (i know from Factor 5 Chris Huelsbeck, they also released some tool for Sega Genesis, afaik it was also on Chris' music CD Sound Factory on 1st data track.

According to that CPU power, GBA have classic Sharp Z80-clone for compatibility with DMG-01, and RISC CPU arm7tdmi, in the past i was familiar with Z80 assembler (learned that in 4 years at high school) and with little stuff like coding diskmags on Amiga (MC 68000), so i also looked at arm7tdmi, but this is another league, so good luck with risc asm.

But GBA sounds classic, i remember game Breath of Fire, this sounds like General MIDI songs, so maybe in BIOS is some midi implementation and little set of samples (of those 128 gm instruments and one drumkit).

Last edited by martin_demsky (Apr 24, 2020 5:46 am)


I think its actually software cause different games use different number of samples but I do agree that the GBA has some great sounds. I've seen people on other forums trashing the GBA sound cause samples tended to sound horrible and they would blame it on the 8bit DAC when in actuality the samples were compressed just to save on space and nothing more. The GBA can actually put out some high quality audio when cartridge space isn't an issue. Its still an issue that still plagues portable consoles but not to as much of an extent as it used to.

Last edited by biolizardshadow (Apr 24, 2020 3:39 pm)