Is the whine at around 9250Hz? Both of mine and my gf's emit the same pitch, I think it's normal to be there in some degree, and it's such a specific frequency that you can take it out of recordings with a parametric EQ and not affect anything else. Dunno how you'd fix it in a live situation though

For what it's worth, I went ahead and gave one of my DMG-001's (the noisest one) a cap kit and, to my surprise, it didn't seem to improve things music. That said, I listened to your recording and I don't hear anything abnormal except that noisy bit right before the square. I think that might not be much to worry about.

By contrast, my GameBoy emits a high pitched whine that is independent of the volume knob and it drives me nuts! My other DMG has that same high pitched noise but it's much much quieter. It's a bummer since that's also my GB with the backlight mod.

In any case, I would try yours out with LSDJ, which has an option to control power save mode and can give you a better idea of how noisy things are. In lieu of that, if you have a game that has spare music or music at a lower volume, you can better judge things.

I would grab a cap-kit from Kitsch and give that a try. I have one ready to go for one of my GameBoy's but haven't sat down and done it just yet since I have another GameBoy I use for recording anyway. Between those two, the difference is massive. The bad one has a really annoying high pitched whine that is difficult to fix in post, whereas the other sounds like silk. Well, ok, it too has a very very slight whine but it seems to be at a different pitch and seems to be basically inaudible when I record it after EQing.

sorry, just remove dot
http://8bc.org/items/images/DMG%20prosound%20mod.jpg

404, on the link bud

haven't pro'd my either of my dmgs, probably should some day but i don't see it as a huuuuuge deal yet

Hello men, i have following experiences: I purchased original Gameboy DMG-01 in great condition without any mods or accessories, waited some weeks for my copy of LSDJ with EMS USB 64M card (ordered from Nonfinite Electronics) and V3 backlight. I installed backlight and card into DMG and noticed little noise and some ghosts during editing. Some days later i found AC Adapter in out local store which have negative polarity and 6 V, when i removed AA batteries and switched-on DMG i noticed in LSDJ some low volume, high frequency whistling. So i did some research in Pro Sound mods and found this great pic: http://8bc.org/items/images/DMG%20prosound%20mod.jpg. After this modification signal is crystal clear and without any "ghosts".

Chainsaw Police: That's something different. That just means that you're getting bad contact for a short while when you move it around. The same would happen if the same plug was attached to a battery pack.

Same. Maybe it's because mine isn't an officially-manufactured unit, but whenever I move the power cable around or push it back in, the DMG's headphone jack (not sure about prodound) makes a scrunchy noise.

I the feedback I get on my gameboy but that's most likely because 1 I have accepted the fact that no matter how many different ways I record it it still has the hiss on it and 2 I have tried everything to hide it and finally I said screw it and I leave it in. Kind of lets people know I record directly from a Gameboy (DMG 1) or  a pocket or a color. Plus it doesn't hurt when you write noisey chipthrash.

Oh, yeah! The "source" of the noise, so to speak, is the CPU, but as far as I understand, it "happens" in the headphone amplifier, depending on how much other parts of the whole circuit can attenuate it. So prosound should still make a huge difference. Also, not all noise components are the same. The power supply itself will also still output a certain amount of noise, even without the help of the CPU.

nitro2k01 - Thanks.  Very helpful info.  The noise is definitely CPU-dependent, because it changes depending on what it's doing.  It reminds me of the interference I used to hear between a video card and Sound Blaster back in the DOS days...

InactiveX - I'm using fresh batteries.

I guess I'll break out the soldering iron and see what happens.

Are you using a PSU or batteries? I find using a PSU adds noise.

It appears to be a bit on the noisy side, yes, but you can always expect noise from the headphone jack of the DMG. From what I understand the most of this noise comes from the headphone amplifier and there are two distinct noise source.
1) "Transistor noise". This is the noise inherent to all semiconductors in different degrees. This is white noise. Not much you can do in the way removing it.
2) Power supply fluctuations/interference. This is just my understanding of it which is hopefully correct. For various reasons, the internal power supply line can fluctuate slightly. This carries over into the headphone signal. When the power supply ducks slightly, so does the signal, and you end up with interference.
This happens because the DC/DC power converter can't always keep up the pace with the changes in load by the CPU.

It gets worse if the batteries are almost dry. (Get new ones, or recharge if they are rechargeable)

It gets worse if certain capacitors are dried out. The cause for this problem is usually dodgy components. Game Gear was notorious for this for example. This is not a known problem for Gameboys, but might still have happened for example if the unit has been stored in in a moisture.

It gets worse when power save mode is on in LSDj as that turns the CPU on and off all the time. In newer versions of LSDj, the power save mode is hardcoded to auto. That's what pixls is describing.

But this noise is always there to some degree in the headphone jack. In my experience, prosounding always gives a nice and clean sound, so I would recommend you to actually do that.

e.s.c. - That link is exactly what I'm comparing to.  The first non-modded DMG audio file on that page (the "play it loud" one, since the very first one is a broken link) is much, much quieter than my sample: -53 dB before the song plays, versus my -24 dB. That's a big difference.

If modding it will make this difference moot, I'm happy with that, I just want to have an idea before I start.

the gameboy is noisier sitting idle than actually playing notes from what i've found.

in general I mean, on most gameboys