Hey all!

So I recently modded my GBC, and while I'm very happy with the results, I'd like to add a bit more umph to the low end.

I saw this: http://chipmusic.org/forums/topic/7723/gbc-bass-mod/

Although the issue I have with this is that the tutorial availible only uses external jacks, while I have an internal prosound mod that runs through the original headphone jack.

How can I do the bass mod with the internal prosound? I'd imagine it would only require wiring the capacitor(s) to the appropriate audio out on the back of the board, but I'm lost as to if that's the case or not...

Any input or help would be greatly appreciated.

Thanks!
-Sam

I've done this using 4.7uF caps and 100 ohm resistors in series, per nitro2k01's comment here: http://chipmusic.org/forums/post/212249/#p212249

In your scenario, if you've added additional wiring for your internal prosound mod, split those wires and add cap and resistor in series there.

If this doesn't make sense, maybe post a pic of what mod you've already done.

Knife Crimes wrote:

If this doesn't make sense, maybe post a pic of what mod you've already done.

Yeah I'm afraid idk.

Here's pics of what I got going on. Purple wires are the only ones you really need to pay attention to.

No diff. Continue on with your mod.

Jazzmarazz wrote:

No diff. Continue on with your mod.

So do I desolder both points (the post-pot and 2/3 for the jack) and just add the capacitors to where 2 and 3 are on the back of the board? Will I be able to control the volume level with the wheel this way? Or is this pre pot?


Or can I just add the capacitors to 2 and 3 and call it a day?

Last edited by nanode (June 26, 2016 5:06 pm)

Shit just did some research and it's pre pot. Any way to get it to work with post pot?

nanode wrote:

Shit just did some research and it's pre pot. Any way to get it to work with post pot?

Yeah. The only difference between pre- and post-pot are which side of the pot you solder to. The rest of the circuit remains unchanged.

Jazzmarazz wrote:
nanode wrote:

Shit just did some research and it's pre pot. Any way to get it to work with post pot?

Yeah. The only difference between pre- and post-pot are which side of the pot you solder to. The rest of the circuit remains unchanged.

So I just need to solder the capacitors to the L/R of the audio jack and keep the wires that I have soldered to post pot where they are?

nanode wrote:
Jazzmarazz wrote:

Yeah. The only difference between pre- and post-pot are which side of the pot you solder to. The rest of the circuit remains unchanged.

So I just need to solder the capacitors to the L/R of the audio jack and keep the wires that I have soldered to post pot where they are?

Audio jack? No. The new caps need to replace two of the original surface mounted caps. Your audio jack just connects directly to the pot.

Jazzmarazz wrote:
nanode wrote:

So I just need to solder the capacitors to the L/R of the audio jack and keep the wires that I have soldered to post pot where they are?

Audio jack? No. The new caps need to replace two of the original surface mounted caps. Your audio jack just connects directly to the pot.

Ok, so I just desolder those two caps like I did with EM2/EM3 and just solder the 47uF's in their place?

Sorry for my constant questions haha

Thats what scannerboy says.
You're talking about this here right:
http://chipmusic.org/forums/topic/7723/gbc-bass-mod/
I also found this
http://chipmusic.org/forums/topic/14184 … oto-guide/
and he does it a little differently. You mentioned connecting the caps to external jacks, which they only do in that second link.

Yeah I was looking at both. tongue

Probably why I got super confused haha

Will stick with the first one in that case

In that case, you will remove the surface mounted capacitors and solder the 4.7uF caps in their place. This modifies the low-pass filter.
He also says "socket and voila.

He also says: "It's super easy if you already have a prosound mod."
Thats because you only need to do the caps and touch nothing else.

Jazzmarazz wrote:

In that case, you will remove the surface mounted capacitors and solder the 4.7uF caps in their place. This modifies the low-pass filter.
He also says "socket and voila.

He also says: "It's super easy if you already have a prosound mod."
Thats because you only need to do the caps and touch nothing else.

Nice! I'll be ordering those caps to do the mod!

sorry for the necro-bump, didn't want to start a new thread for this one stupid question:

I have an external post-pot pro-sound jack. do I need to remove caps on the board before adding the  4.7uF caps? katsumbhong's tutorial shows pre-pot only, and doesn't mention removing any caps, so if so, which caps do I need to remove?

Last edited by urbster1 (October 21, 2016 7:15 pm)