NeX
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Hi all, i just finished my SP pro sound and i thought i would share it all with you.

when the SP first came out i rejected it straight away, nintendo went and took the hard core gameboy and put an easy to break hinge on it. my experience with laptops taught me that hinges are the first to go.

but i bought one of ebay for the sake of trying out every gameboy nintendo have to offer, and recently i went back to it. now i have fallen in love with it! and like every new loving relationship i straight away started to hack and butcher my SP with dremals and other power tools.

first thing i noticed when opening it was the total lack of space. this gave me mixed feelings, i was glad nintendo were using all the space they could, but it left out all the moding posibilities. but i like a challenge so it was still a positive thing to see.

first of all i had to pick a space for the jack. as with all my mods i don't want to loose any features of the gameboy, so taking out parts is a no go, it must work exactly as it did before but better!

so i picked a spot just below the volume control but there was a stupid little capacitor in the way (goes between true ground and audio ground, it helps with heavy bass by acting as a power buffer)
so that had to be moved out the way.

then i needed to mod the case to fit the jack socket in. i used the jack socket from a pocket gameboy as i had it lying around, and it has a mute switch built in.

then i wedged in the socket, it has a nice fit so that it doesn't need gluing or anything and its still strong.

then a bit of wiring.

this was the real bitch. i found the pro sound points easy enough, they are even labled, but getting the internal speaker to mute was near enough impossible. the problem is that its not like a pro sound on a DMG, where the audio from the CPU is put through a parallel pot, it is run straight to the amp, and then the amp drags everything to ground when you turn the volume down. so it cant just be wired to the back of the pot because it doesn't work that way, and it cant be taken at the CPU because they are still attached to the amp and so the volume pot, and cutting the traces would loose the internal speaker.

the first contacts i wired to gave me pro sound, but it was still wired to the volume control so if i turned down the internal speaker it took the pro sound with it. so i chose some points a bit further back which were much louder but they took too much power (before the cap so no buffer) and it caused distortion on the screen. i might try again and see if i can adjust the power to the screen to make that a bit better,

so i had to use the first contacts again, but i now needed a way to mute the internal speaker, but the internal speaker mutes when the switch is connected to ground, where as in the older gameboys it was disconnecting from ground that caused the internal speaker to mute, and i am using a pocket headphone jack.

so i decided that because the pro sound is before the amp, i don't need the amp when using the pro sound. so i ripped up the ground pins on the amp and connected them to the internal switch in the headphone jack. that way everything acts as normal when there is no jack in there, but when the jack is inserted it breaks the contact from ground which cuts power to the amp, and in tern the internal speaker.

but this does give a weird effect where the pro sound is quiet until you turn the volume down on the SP, then the volume goes up on the pro sound. i think it has something to do with how the amp mutes by dragging everything low.

the final socket.

an-cat-max
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astral cat

that's amazingly clean looking!

NeX
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thanks! its wedged in there pretty good, i worked out there was space to fit it and drilled all the holes and then forgot how i was actually going to get it in. in the end i had to use a bar of metal to bend the plastic just enough to push it in, now its held there pretty solid without glue or anything like that

an-cat-max
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astral cat

that's great, looks like it was always meant to be there smile

arottenbit
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Milan, Italy

Yay. Awesome. Very clean!
..but really too hard soldering points for me.. tongue

Have you compared the sound output using the headphone adaptor and this mod?
Is it a real prosound (less hiss, hum and stuff) or it's just an (awesome) integrated jack output?

NeX
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arottenbit wrote:

Yay. Awesome. Very clean!
..but really too hard soldering points for me.. tongue

Have you compared the sound output using the headphone adaptor and this mod?
Is it a real prosound (less hiss, hum and stuff) or it's just an (awesome) integrated jack output?

yea i know, i dropped a blob of solder on the chip, it took ages to clean!

i am still waiting for my headphone adapters to arrive in the post so i haven't had a chance to check it yet. i want someone else to give it a try and see what they think. to me it sounds pretty clear, except for a small distortion on high notes, but from my tests, that seems to be the best that the SP can do as it is the same with the internal speaker.

in theory it is a true pro sound, the audio is taken raw before it enters the amp. this is where it picks up noise, when you have power and audio together (like in an amp) you get interference, and because this amp is so small, they had to sacrifice audio quality for size. so the idea is to take the audio before it goes through the amp and put it through a proper amp which will make it a lot cleaner.

but all i have is computer speakers at the moment to test it with. it does sound great, but it has about as much distortion as a gameboy pocket, which is more than the DMG so the DMG is still the best for crystal clear sound.

i suppose in the end its don't to personal preferance and if its acceptable.



COME ON someone give it a go i want feedback! lol

phib3r Optik
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Charlotte

Thats epic! I have been wanting to see someone do that! haha

low-gain
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Milwaukee, Wisconsin USA

OK.. I'm going to drop in and be mr. negative only because i've been down this road already and didn't bother with the mod because of it..

There's no room in this thing to mount the jack w/ the necessary components to make the output a safe one.
Taking directly off the IC like that isn't the ideal thing and it's far from "Pro Sound". It's leaving the chip vulnerable to the outside world.

You need 2-3 things..
series R, R to ground and and output electrolytic cap.

They might also help w/ your distortion issue.

Besides the fact that i dont like this mod being done to the SP... your jack installation is very clean and nice.

If you get creative with SMT parts you might get some better results with your audio signal.

I'd try to first reverse engineer the output circuit. And see what it looks like and see what could be done to reduce the noise.
I would think perhaps some extra filtering would help with the high frequency crap that usually comes off the output.

low-gain
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Milwaukee, Wisconsin USA

One other thing i'd recommend..

Just figure out the pinout on the output jack slot and do all your hardwiring internally and use the connector like normal.

That is of course if you can get the SP to sound better w/ modificaitons. if you can't... what's the point of doing the mod to begin with?

NeX
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low-gain wrote:

OK.. I'm going to drop in and be mr. negative only because i've been down this road already and didn't bother with the mod because of it..

There's no room in this thing to mount the jack w/ the necessary components to make the output a safe one.
Taking directly off the IC like that isn't the ideal thing and it's far from "Pro Sound". It's leaving the chip vulnerable to the outside world.

You need 2-3 things..
series R, R to ground and and output electrolytic cap.

They might also help w/ your distortion issue.

Besides the fact that i dont like this mod being done to the SP... your jack installation is very clean and nice.

If you get creative with SMT parts you might get some better results with your audio signal.

I'd try to first reverse engineer the output circuit. And see what it looks like and see what could be done to reduce the noise.
I would think perhaps some extra filtering would help with the high frequency crap that usually comes off the output.

honest negative coments can be more productive than positive ones wink

there is two resistors between the audio lines and ground, the points that i took the pro sound from are after these two resistors, i did try directly from the CPU and it had more volume but caused distortion in the screen (and as you said left the CPU vunrable)

there is also a capacitor to ground on the audio ground (ironically the one i had to move to fit the jack) so the components are there, the sound distortion seems to purely be a problem with the CPU from the start, though when using normal carts over the USB carts (tested with tetris and the gameboy camera) the sound is a little bit better,

i think the built in array of noise filters is on the other side of the pre amp, which i chopped out of the loop, though if you plug it in to a decent mixer it should have filter options built in.

the SP is a pain in the ass to work with and in a way i don't like it, its a good unit as standard, and the ability to play all gameboy games and comes with a backlight is very useful, but maybe its guts would be better in a DMG for space, and that retro feel that we all love wink

anyway, still waiting on other opinions of the pro sound quality,

NeX
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low-gain wrote:

One other thing i'd recommend..

Just figure out the pinout on the output jack slot and do all your hardwiring internally and use the connector like normal.

That is of course if you can get the SP to sound better w/ modificaitons. if you can't... what's the point of doing the mod to begin with?

a well, the main reason was i have plans for those extra pins on the standard connector, a few more mods i want to try on the SP, plus everyone has a 3.5mm jack, but not everyone has the adapter, so at a show etc all you need is the SP which is why i added the socket,

i still belive this sound is better than the stock sound, but by how much and if its worth the effort....not sure, i only did it to see if it could be done. i don't make music good enough anyway lol

low-gain
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Milwaukee, Wisconsin USA

well like i said, you need to add protection to the output.


and as for the adapter... i carry at least 5 of them on me at shows.. anyone who performs w/ SP's should know better wink

arfink
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Minneapolis

Huh, I think there's a good chance this could be fiddled with to the point of actually working. You'd need to get very creative with placement, but I believe there IS room in there to do it right. With SMT's is almost a given though.

And you're totally right Low-Gain, hauling that line outside the case with no protection circuit is just begging to fry the CPU with some lovely ESD or adding the possibility of more interference.

EDIT: Low-Gain has a good point though- if an improvement in sound ultimately cannot be made, then internalising the jack is merely cosmetic. A very nice cosmetic plastic surgery, don't get me wrong. smile

Last edited by arfink (May 22, 2010 5:36 am)

NeX
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ok i will double check what i have done, but like i said i am pretty sure there is the components needed to protect the CPU and i am pretty sure the sound is over all better than the original, no hissing or buzzing, its crystal clear, its just a slight distortion, which could actually just be the drumkit i used on LSDJ, because all the other channels sound fine.

and again, i want someone else to give it a try, report back, i only did this for fun, i need someone who really knows their stuff when it comes to sound quality to go over and check what i have done.

there is plenty of space to put a couple of SMD resistors and a capacitor on there too, in fact i did try a 100uf SMD electrolytic cap from true ground to audio ground, but this seemed to created more interferance. i really do think that when nintendo tried to make the SP so small, (in some ways its even smaller than the DS internal free space wise) that they had to loose some sound quality in the process, they are a big company producing cheap handhelds for kids, sound quality is not an issue for them.

arottenbit
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Milan, Italy

ok.
I've got a broken GB Poket (for the jack output) and a GBA SP without backlit (used to mod a GBC).
I'm going to try this mod this afternoon. smile

edit:
i need to know the soldering points.

Last edited by arottenbit (May 22, 2010 9:52 am)

NeX
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arottenbit wrote:

ok.
I've got a broken GB Poket (for the jack output) and a GBA SP without backlit (used to mod a GBC).
I'm going to try this mod this afternoon. smile

edit:
i need to know the soldering points.

awesome, pin outs are here:
http://8bitcollective.com/images/NeX/ga … +prosound/