Sorry for double posting,

I actually bought two dehum capacitor kits from retrosix and installed in one of my GBAs plus performed that internal amp bypass/prosound mod that scannerboy suggested from a thread here on the forum (See Photo).

Unfortunately I can’t say that I’m very happy with the result. It could very much be my lacklustre soldering skills, but I felt that I did a rather decent job.

Maybe someone with more knowledge in electronics could tell whether the internal prosound mod could cause the noise and mess with the capacitor de-noise mod?

I’ll update this post with photos and sound recordings tomorrow.

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UPDATE 2020-11-15
Sorry, didn't get to do this earlier. I'm gonna upload some photos too!
The GBA without the dehum capacitor mod has its' amp bypass routed from the points from behind the PCB.
Don't think there should be any difference compared to the points next to the a and b button pads from the front side of the PCB but your knowledge may vary.

GBA w/ ProSound Mod/Amp bypass (without the dehum capacitor kit)

Booting Nanoloop 2.8.2
Extract from song

GBA w/ ProSound Mod/Amp bypass with the dehum capacitor kit
Booting Nanoloop 2.8.2
Extract from song

Thank you for sharing this. It might be something I'm gonna have a look into
I especially found this very interesting:

PriMieon: I did like this on a 32 pin GBA: soldered the positive capacitor leg to the power switch pin with a C above it and the negative to the ground pad to the right next to the switch.

I guessed which holes to use (close to the ones on the 40 pin instructions) and traced them to the power switch with a multimeter. Not 100% sure it’s correct but it reduced the noise a bit I think. If this is wrong please let me know, see it as an experiment for now .

Here is another method that I think seems better, haven’t tried it though. https://support.retrosix.co.uk/support/ … -gba-audio

Since 32 pin and 40 pin GBAs are different does anyone know what holes to use with the 32 pin board? I included a pic of the boards. Upper one of 40, lower one is 32.

works fine for me with a big one. I just removed some plastic of the shield.
The noise is acceptable now.

I went to the electronics shop today and they actually had some 1000uf 16v caps, but I've just tried to fit them in the case and they are physically too large.  I'll have to go back and see if I can find some smaller 5v ones that will hopefully fit better.

Yeah I went to radioshack here in the US and thought the dude handing me the 50v was a joke because it was so big.... so can confirm 50v is close to the size of your thumb!

anything above 5v should be ok. 50v is probably too big in size.

will it fit into the casing?

I can only find a 1000uF  50v locally.  Is 50v too big?

it's 1000uF = 1F, generic model should be fine.

Thank you so much for this oliver! Could you maybe share a link to where you'd recommend to buy these capacitors ? Would any generic 100uF 16v capacitors from like amazon be sufficient ?

Well, it may depend on the unit, I'll try it with my other one, too. On this one, the difference is quite noticeable. The hum is still there, but at a much lower, SP-like level.

Did you use full 1000uF? Smaller capacitors don't work.

I tried the mod and to be honest I heard only a little to no difference depending on the unit