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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-TrainingNameless One
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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
    OPN2 in DNA 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
    OPN2 in DNA 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
    OPN2 in DNA 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.

  7. #202
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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.
    Can you show how you reduced it with a picture?

    My JP MD2VA1 also has this terrible hiss noise which occurs when there is no game sound i.e. Everdrive menu. When I move up and down the menu to filter through games, the volume / pitch of the audio buzz changes.

    I have been reading some old posts on here and some say it is indeed due to the fact that the YM3438 is integrated with the VDP chip, and to put capacitors on the supply lines can possibly reduce it.

    I think Ace also mentioned this audio hiss which comes from all MD2VA0~VA1.8 consoles in his comparison thread.

  8. #203
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    Is anyone on this forum still selling these?

  9. #204
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    Quote Originally Posted by whitezombie View Post
    Is anyone on this forum still selling these?
    I've just designed this board according to Ace and Villahed94's original Mega Amp 2.0 mini design. Still awaiting PCB delivery, and I'm hand assembling but I might be able to put together a couple extra if people are interested.

    Attachment 14922

  10. #205
    Death Adder's minion The Real Phoenix's Avatar
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    Hi all.
    I've just publish my attempt on the Mega Amp 2.0 Pro:


    Here's the depository on Github:
    https://github.com/TRP-Retromods/MegaAmp2Pro

    Edit: adding OSHPark link: https://oshpark.com/shared_projects/HAlIFjbQ

    The version on Github is already with the 330ohms + 47F in series to replace the 220F caps. Also the distortion on the mono output is fixed as Ace asked me to do.

    Cheers,
    Last edited by The Real Phoenix; 05-25-2019 at 06:19 PM. Reason: adding OSH Park link

  11. #206
    Video Game Modder Outrunner segasonicfan's Avatar
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    Quote Originally Posted by The Real Phoenix View Post
    Hi all.
    I've just publish my attempt on the Mega Amp 2.0 Pro:


    Here's the depository on Github:
    https://github.com/TRP-Retromods/MegaAmp2Pro

    The version on Github is already with the 330ohms + 47F in series to replace the 220F caps. Also the distortion on the mono output is fixed as Ace asked me to do.

    Cheers,
    Fantastic!! thank you so much for sharing this. I've been hoping that someone would make a nice open source one for some time. And it even has Eagle files! Way Past Cool.

  12. #207
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    Very nice, indeed. Will definetely try it once I get my hands on a MD again.

  13. #208
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    Hey guys,

    I just finished reinstalling all the caps into my Genesis 2 again. Tried to get the Mega Amp 2.0 Pro to work. I don't know why it is like this but I have 3 PCB's here where R12 is connected to Pin 7 (should be Pin 2) of the TDA. The only thing I could get today was the static noise with white images. Nothing else, no mono, no Stereo, nothing. I am pretty sure everything is installed the correct way for a VA0 version.

    Help me! Anyone tried to use The Real Phoenix`s Rev. 2 PCB?

    FIY: the first tl074 died in smoke cuz I mounted it the wrong way. Rest of my board looks great tho.

  14. #209
    OPN2 in DNA Hedgehog-in-TrainingRoad Rasher Peeteris's Avatar
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    Quote Originally Posted by Vorenge View Post
    Hello there, I have diconnected TR1 & TR2 to the MegaAmp, so the wires to R31/C55 & R28 aren't connected.
    I disconnected them because it decreased noise.
    Now I plan to get MegaSD and this raises questions - are these TR1 & TR2 related to Sega CD, even though I have already connected Sega CD L & R channel wires from corresponding capacitor legs to MegaAmp 2 Pro. Will there be no CD audio if I don't connect wires as seen above in the picture, or can I leve TR1 & TR2 on MegaAmp disconnected?

    Thank you!

  15. #210
    OPN2 in DNA Hedgehog-in-TrainingRoad Rasher Peeteris's Avatar
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    Anyone? About TR1 & TR2.

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