145 Reply by m00dawg

(35 replies, posted in Nintendo Handhelds)

It's interesting you mentioned that because I was coming up with the same conclusion (about aliasing). I found this while looking up the various different dithering mods used when downsampling and it turns out that the noise when opting not to use any dithering options is similar to the results I was getting from the DMG.

I'm not sure why though - there wouldn't be any reason for the DMG to increase the bit-depth of the original source but I do find it a bit suspicious. I assume the CPU itself is generating the tones and, if so, I don't think it can be easily avoided without using a lowpass filter (and thus reducing some of the highs you do want). If the DMG uses some sort of DAC though maybe there's a chance smile

I don't know enough about the DMG's audio pipeline to really say, though the down-sampling just wouldn't make any sense to me and is not something I noticed on the NES so *shrug*

Maybe it is just an interesting coincidence smile

EDIT: Actually in thinking about this more, vgx already mentioned the GB has some aliasing so that's probably what I am hearing. I'm not sure what causes that with the GB internally yet but that seems to be the likely candidate.

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146 Reply by m00dawg

(35 replies, posted in Nintendo Handhelds)

Curious as to if it has high pitch noise after the mod, but I guess only time will tell. If it does, I wonder if I can beat that with some filtering caps. I used larger than necessary input caps for my NES audio mod and I think that may be one reason why the high frequencies taper off a bit, though it's just a theory (I need to record it from the original line out and compare which I may try out tomorrow).

It's not an insurmountable problem, though one I can fix outside of my DAW's EQ would be preferable of course. That solution seems to work just fine, however, though it does cut some of the highs I actually want in the recording.

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147 Reply by m00dawg

(35 replies, posted in Nintendo Handhelds)

Here they are:

GameBoy, NES.

The NES actually goes up in to the higher frequencies than I thought, but tapers off nicely. The GB starts to taper off and then it just flattens out into the higher ranges. I think what I am hearing is probably more so those erratic spikes than the higher registers themselves perhaps.

Some of that, to me, looks like noise, so I'm hoping that perhaps the Pro-Sound mod can get rid of some of that. I suspect I will still have to EQ the GB to filter out those highs, though.

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148 Reply by m00dawg

(35 replies, posted in Nintendo Handhelds)

It's not hum in this case, though I know what you are referring to there. It's more like an overtone than a hum - it can only be heard when playing a note. It's definitely more faint than the actual note itself and starts at 7-10kHz according to Ableton Live (using the EQ and spectrum analyzer). I was able to defeat most of it by setting up the 8-band EQ and using a roll-of at about 4kHz (haven't been able to setup a tight rolloff in Live...hurhmm).

I suspect you are right in that it has to do with the GB itself. I tried it on my DMG-CPU-02 and 06 units and they both produce the same high pitched results in this case. It affects the PW channels too so it's not the WAVE bug in this case. I haven't tried the noise channels but they are sort of a different animal I suspect.

I looked at the results of some of my NES recording and the high pitch rolloff is much steeper than I'm getting on my GB. I should probably post screenshots but it's a bit late over here so perhaps I will tomorrow if anyone wants to see the difference.

I assume it's just the nature of the beast but thought I would check to see if anyone else noticed it.

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149 Topic by m00dawg

(35 replies, posted in Nintendo Handhelds)

Sort of on the heels of this post, silly me, I figured out the whole wave thing but now I've noticed that sounds from the GameBoy seem to have high pitched overtones I didn't notice before.

I didn't notice it at first until I made a simple sine wave for the WAVE channel in LSDJ. But after looking at that, I listened to the squares and they do the same thing too. So it sounds inherent to the GB - just trying to figure out where.

Is this something the Pro-Sound mod solves or am I just going to have to EQ things or run things through a slight low-pass filter?

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150 Reply by m00dawg

(2 replies, posted in Nintendo Handhelds)

*oh* Hah it was in the "PLAY" menu item. Got it. Wow I was so close yet so far ;P Thanks for the super quick response!

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151 Topic by m00dawg

(2 replies, posted in Nintendo Handhelds)

I've been at this for awhile and haven't made much progress. The problem is that I just really want to play a single wave on the WAVE channel. In this case, just a sine wave.

I didn't see a setting in the synth or instrument menus to do that, however. Since the wave patterns are cycling, I get clicks which can be quite clearly heard when using a sine-wave as the waves are cycled. Since the sound isn't really changing, the clicks are just getting in the way.

I know you can slow down the speed that the cycling occurs in the instrument menu - is there a way to just turn it off altogether?

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152 Reply by m00dawg

(9 replies, posted in Nintendo Handhelds)

This guide should help - specifically this image.

Pre-pot = no volume control for the pro-sound mod, but you can still use the GB speaker using the volume knob as you normally would. A bit louder.

Post-pot = Volume controls the pro-sound mod and GB speaker (so you might want to disconnect the speaker or figure out a switch). Less loud than pre-pot though still louder and cleaner than headphone out.

Note that I haven't done this mod myself so don't hold me to that (hold Kitch to it instead smile )

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153 Reply by m00dawg

(9 replies, posted in Nintendo Handhelds)

Cool, that's perfect! Thanks Kitsch!

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154 Topic by m00dawg

(9 replies, posted in Nintendo Handhelds)

I've been reading up on the Pro-Sound mod and most of the documents I have found call for wiring it up after the pot (so you can control the volume). But that seems a bit odd to me if the purpose is for recording, because the output should be controlled by your mixer or in post?

I noticed ASM mentioned in another post that you can connect the wires before the pot, which makes the most sense to me.

The question I had was if wiring it up before the pot ends up causing any distortions or any undesirable affects? Otherwise it seems like the way to go (can keep the GameBoy speaker connected this way too).

?

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155 Reply by m00dawg

(15 replies, posted in Nintendo Handhelds)

Thanks for the info all! For some reason I wasn't getting e-mail updates on this thread (that reason being I forgot to click subscribe hmm) but some good stuff here thanks! ASM mentioned to me off-list that it might be a bit cumbersome to replace all the caps so it might be a "do it if you have to" thing.

@2Player, I do indeed have a DMG-02, but I was also able to score an 06 (oh man did that make a difference!) that's in better shape overall I think. That'll be the one I do all the mods on I suspect.

@Kitch - thanks and you're welcome! (Saw the mention on the Twitterverse) I'll likely be grabbing these up at some point soon! Looking forward to the NES one as well (I replaced a few already but not all the ones in the RF module since I don't know of a good way to get that sucker off) and it made a noticeable difference.

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156 Reply by m00dawg

(6 replies, posted in Nintendo Handhelds)

Indeed it was! Sorry to see but hey the schems are available so who knows!

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157 Reply by m00dawg

(31 replies, posted in Nintendo Handhelds)

One thing that bugs me about the NiMH is that, if they produce 1.2V for most of their discharge time, that only ends up being 4.8V. 1.5V advertised by Akalines (although from what I've read, they too can drop to 1.2V after some time) ends up being 6V which is also the input voltage when using the adapter.

Doesn't seem to be as though anyone is worried about it much, and the DMG seems to work fine but I'm curious as to what is going on electrically in this case. I was under the impression that the DMG stepped 6V down to 5V for everything but the LCD. I assumed a regulator was used for that, but a linear regulator would not work in cases where you were already under the output voltage, no?

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158 Reply by m00dawg

(31 replies, posted in Nintendo Handhelds)

I was a bit worried about the lower voltages of NiMH rechargeables, but so far I haven't had any problems. I have a rather nice charging station though that lets me control how fast/slow to charge batteries, has a discharge feature, among other things. I think the negative feedback I see from rechargeables is due to crappy chargers and/or poor handling.

That said, I've been wondering about creating an external battery pack using lithuim batteries. SparkFun has some nice offerings that should make it pretty easy to do, I would think.

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159 Reply by m00dawg

(6 replies, posted in Nintendo Handhelds)

herr_prof wrote:
kitsch wrote:

i sent off an arduinoboard design to the fab house 2 days ago.


!!!

Haha yes, agreed! I'm likely go grab up whatever Kitsch ends up making, though I was likely going to move forward with this design, in part for fun, and also so I can have something up and running in case it takes Kitsch a while to end up having a solution.

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160 Reply by m00dawg

(6 replies, posted in Nintendo Handhelds)

I hadn't thought of moving the MIDI connections out and flipping them actually, that's a good idea.

In regards to the layers, I originally tried to keep it as a single layer though I had to make a few bridges. I got stuck on one connection and since I was already thinking about using BatchPCB for this board I ended up just going with a two-layer.

I did go a bit crazy with the layers, mostly on the LED section. I figured "why not?" and I thought that staggering the traces would help with interference (as if there would be enough to mess up simple signals, but I mean if I was going for a 2-layer anyway).

I was also trying not to expand the shield out more than I had to which was proving to be a challenge since I kept running into cases where I would have to wires along the top of the header to avoid using a bridge or a 2nd layer.

In hindsight I think a standalone board might be a better option, although I was unaware that the cable didn't supply 5V by default, doh so that kinda tips the scales back over to a shield style design.

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