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Thread: Take your Genesis audio to the next level - The Mega Amp 2.0 is here!

  1. #196
    Hedgehog-in-Training Hedgehog-in-TrainingSports Talker
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    Well, if you have noise in your circuit, then amping it will only make it louder. Curious, Appears to be a VA0 Model 2, is that right?
    - I see the Mega Amp Pro. I don't have that one nor the schematic for it, but I know there are similarities except for the Sega CD passthrough which it looks like you're working with by the removed resistors and capacitors under the power switch.
    - It appears you have a solder bridge connecting R31 and C55. I'm not sure if that is supposed to be there.
    - Near your Mega Amp board, are the R73 and R72 resistors both removed and replaced with a solder bridge?
    I can't see much else of your board or from this view to guess anything else. I boxed what I can see.

  2. #197
    YM2612 in soul Hedgehog-in-TrainingRoad Rasher Peeteris's Avatar
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    Yes it's a VA0 board.
    AFAIK, R31 and C55 are bridged on the board anyway. I'll try later to remove that bridge and wires and post a results here.
    R73 and R72 are removed and there's bridge soldered.
    If it'll help, I can post a pictures of the whole board.

  3. #198
    YM2612 in soul Hedgehog-in-TrainingRoad Rasher Peeteris's Avatar
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    Update!
    What I gathered so far:
    1.It's not an AV cable, because when I disconnect it and connect 3,5mm audio jack straight to the MegaAmp board, it still hisses and has digital(!) background hiss/noise.
    2. Unbridging R31 and C55 does nothing. Removing wires from there(TR1&TR2 on MegaAmp) also does minimal to no effect.
    3.Maybe this noise can't be cancelled, because YM3438 is integrated and it gathers that noise from inside the chip? But I also tried to add 3,5mm jack directly to YMR, YML and ground pins and noise wasn't there, although maybe I didn't hear it, because volume is way lover than from amplifier outputs. (?)

    Maybe I'm just nitpicking, but if we compare my Model 1 Mega Drive VA6.5 and this modded Genesis model 2, then we can hear the difference (regarding background noise)
    https://drive.google.com/file/d/1jNF...ew?usp=sharing
    00:00 - 01:15 - MD1
    01:15 - 02:36 - Genesis 2 (Mega Amp)

  4. #199
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    Try comparing with Thunderforce II if you have it. That game just seems to pick up logic noise like no ones business.

  5. #200
    YM2612 in soul Hedgehog-in-TrainingRoad Rasher Peeteris's Avatar
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    Ironically, that game is perfectly silent.😀👍
    Also, I soldered nicely 3.5mm jack and audio from there (if connected to some audio system) is actually bearable. Yes, every change on the screen still makes differet bg noise, but at least that terrible hiss is not that prominent.

  6. #201
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    Quote Originally Posted by Peeteris View Post
    Ironically, that game is perfectly silent.😀👍
    Also, I soldered nicely 3.5mm jack and audio from there (if connected to some audio system) is actually bearable. Yes, every change on the screen still makes differet bg noise, but at least that terrible hiss is not that prominent.
    I thought your sound sample was pretty good Peeteris. I hear the faint noise you're talking about. There are so many things to consider. If you're still exploring, you might want to try a re-cap since it appears you have your original capacitors. The only thing is that it may or may not help. I replaced all mine when I did my mega amp(s). The thing is that eventually they have to be replaced anyway. Besides that and not really wanting to recommend a hack, but sometimes you can kill some line noise by placing a couple of resistors on the output lines before connecting the 3.5mm jack. That lowers the volume a little (not much if you use small value resistance like 27ohm) by doing that and you'd have to raise it on your speakers. Just thought to share in case you want to experiment, but overall I think your sound is much better after than before, but I sure don't blame you for nitpicking - because that's exactly what I would do too.

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