A) LM386 as a gameboy sound amplifier.
try using a LM386 amplifier in your gameboy to get a brighter and higher sound output.
you can use any speaker above .5W - the above diagram was tested with a .5W and worked great.
this diagram is a product of my own experimentation and research, and so far, it works for me.
1. 1 x lm386 chip, preferably from a good brand, I have found that generics add some noise.
2. 1 x 10k resistor.
3. 1 x .5W (at least, I have also tried 1W and worked fine as well) mini speaker.
4. 1 x 470uF electrolytic capacitor.
5. 1 x 223k ceramic capacitor.
6. 1 x 224k ceramic capacitor.
WARNING - there is a downside in this configuration:
as soon as the gameboy powers up, you'll hear no sound coming out.
in order to make it work, you need to turn the volume up to the maximum...and wait for 5-10 seconds until sounds starts coming.
sound will start coming out distorted - don't worry. so, once this happens, you'll need about 5-10 more seconds to get it clear and nice.
given this, it's quite likely you won't hear the nintendo bell when the gameboy starts...be warned.
it sounds like the electrolytic cap needs to charge before actually being able to amplify and get all output.