Optimizing Audio on the original Gameboy DMG

[tablebeast]

I'm currently planning a mod project with an original grey Gameboy. I want to make some chiptunes on it. The unit I have is a nice and clean original unit, so of course I need to hack it up! These original models supposedly have the best bass response and the most "authentic" sound of all the Gameboys, but it is a noisy *******! The power supply regulator board is weak, the headphone amp is garbage, and the wiring/routing is not set up for audio quality. Plus, best case scenario, the caps are cheap AND ancient!

Being such a common and well loved device, especially one used by musicians, you'd think there were a lot of these modded for audio use with documentation, but I'm not seeing much. At least not to the level I want to take it. There are a million pages on the web dedicated to vintage gaming and even dedicated to making music with different Gameboy carts like LSDJ, Nanoloop, and mGB. But they all talk about bypassing the headphone amp and call this vaguely a "prosound" mod. "Pro Sound" is a funny way to describe the noises that come out of this toy, but they are interesting enough to me, so I want to get the best audio quality I can out of it, "Pro" or not. So anyway, here is my initial plan for an ultimate DMG Gameboy made specifically for music and performance.

1. Recap the whole thing and bump up the values and quality of the caps in the audio path. (I'll probably roll my own here and avoid using a "gamer" kit)
2. Put in a new regulator board with better filtering and capacity (I'll try to figure out the best kit with the lowest noise, but I'm open to DIY)
3. Backlight mod for the original screen that has the quietest operation.
4. Actually shield the audio wiring.
5. Install a 1/4" output jack (or two) connected directly to the line amp BEFORE the volume pot and headphone amp.
6. ClockxControl mod that replaces the original crystal with an adjustable clock.
7. Convert to a smaller, 6v, rechargeable battery pack.

There will be likely be more mods done to it, like CV/MIDI, but these should get me started. I've included a pic of the insides and the schematic for your perusal.

Anyone else mess with one of these?

 

[tablebeast]

Most of the parts are figured out and ordered now: cart, caps, jacks, screen and clock kits. I just need to figure out a rechargeable battery pack situation. I will need about half of the battery compartment area for the 1/4" output jacks, so I won't be able to install those until I reclaim that space.

 

[tablebeast]

Some of the parts are coming in now! You're looking at orders from Mouser and Handheldlegend:

1. 2x 1/4" jacks, nice and small. These are for the main stereo audio output and will occupy internal space vacated by using a smaller battery pack.
2. 3x 1/8" jacks. These are for tapping the sync in/out and clock connections from the link cable.
3. New volume pot. Because obviously.
4. Bi-vert screen mod kit to improve the newly backlit display.
5. Recap upgrade set. Tiny audio grade Nichicons for the CPU board with increased values in the audio path. A 1000uf filter cap is added to the voltage regulator. Then there are some Kemets for recapping the rest of the display board.
6. Backlight mod kit for original screen. Modding the original screen was chosen over IPS screens because of voltage draw (requiring a new regulator board) and overall noise performance.

Notes:
- I ordered three sizes of 1000uf 10v caps, but none of them fit where I want it to, so that may change.
- The two 100uf caps for the display board are a little too big and don't need to be audio grade anyway, so those will change.
- The size of the jacks I ordered are perfect and the quality has exceeded my expectations. They are made by Same Sky, who I hadn't heard of. I will look for their products again!
- I still need to find the right battery pack and USB charging mod that matches up with all the other stuff I'm doing. This is the last piece of the initial parts puzzle.


.