High Pitched Noise Coming From GBC Speaker? Try This!

The Game Boy Color is absolutely notorious for sound issues. It's system is somehow too quiet AND too noisy at the same time. I have seen a lot of mods floating around on the Internet showing how to make the system louder, but none showing how to fix the audio quality issues. The GBC's high-pitched hissing sound can even be heard in some DIY-upgrade videos through the microphone. I'm not sure if ALL GBC's have this issue, but I know for sure that mine did. Here is how to fix it:

What we are going to be doing is installing a low-pass filter across the speaker of the GBC. Here is what you will need:

1 20-22uf Capacitor. (Preferably a lower voltage one for space)

1 1Ω Resistor

Thin gauge wire - preferably braided

PCB prototype board

A GBC-compatible tri-wing screwdriver

A soldering iron

Solder

Flush Cutters (recommended)

A replacement speaker (optional)

Flux (optional)

Starting out I would like to point out that there are many combinations of resistor and capacitor you can use to make this project work. Technically speaking, you could also use an inductor in a different configuration if you felt so inclined, but don't worry about that right now. I would highly suggest that you order a variety pack of capacitors and resistors off of Amazon. That said, if you are bound by the parts you have lying around, you can use this website to figure out a balance of capacitor and resistor to suit your needs. We are shooting for a cutoff frequency of about 7-10khz. (Retro games rarely use frequencies above 5khz.)

The circuit:

So here is what you are gong to want to do:

- Take your PCB prototype board and place the resistor and capacitor. Solder these together. Start in the middle of the PCB to give yourself room for when you trim it.

- Take a ~.75 inch wire and solder it to the positive terminal on the capacitor.

- Before moving forward, make sure to de-solder the speaker from your GBC. Leave the wires hanging on the board for later.

- The stock GBC speakers tend to degrade over time, so you may consider replacing it all together in this mod.

- Take your flush cutters and trim your PCB down. Leave a hole on either side of the resistor to connect from the GBC to.

- Take the wire hanging off of your freshly-trimmed board and connect it to the right-most terminal on your GBC speaker.

- Take the top hanging wire from your GBC and connect it to the right-most terminal on the speaker. There should be two wires connected to this point now.

- Solder the bottom hanging wire on the GBC to the Vin side if the resistor.

- Finally, connect the Vout side of the resistor to the left-most terminal on the resistor. Make sure all your solder joints are in order, and presto! You have implemented the circuit!

The Implemented Circuit:

For ergonomic reasons, Nintendo left plenty of open-space behind the speaker in the GBC. We will be taking full-advantage of this and using it to house or circuit. Take the circuit and use the wires to float it above the speaker like so:

Normally it is considered poor practice to float a board with wires, but it is the most simple and effective option here. Finally, put the shell back on, and viola! You are done.

Note that this mod should also work with the sound amp mod; just make sure to use the amplifier output instead of the board's signal output. You could also try running the low-pass filter before amplification, but in this context I think it would be more effective after. You still may have a few minor audio flaws after installing this mod if you put the speaker right up to your ear, but this should reduce at least 90% of the unwanted noise coming out of the speaker. Also note that the circuitry here is universal! This mod would also work in a GBA or DMG if you had issues in those systems.

I would like to shoot a video on this mod, but that is contingent on me acquiring another GBC by the end of the month, as I am moving across the country. At any rate, I will update this thread with a video if I get around to it. Anyways, hope this helped you guys. Cheers!