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

  1. #1
    Creator of the Mega Amp Raging in the Streets Ace's Avatar
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    Sonic Take your Genesis audio to the next level - The Mega Amp 2.0 is here!

    On January 1st, 2014, myself and Villahed94 released the Mega Amp, a universal replacement audio amp for the Genesis. Three years later, we present to you the next evolution of the Mega Amp...



    What makes the Mega Amp 2.0 different from the original design?
    Due to limitations of the chosen op-amps on the original Mega Amp, volume levels are limited to those of every Genesis made from the VA0 Genesis Model 2 onwards. With new components chosen for the Mega Amp 2.0, you can now blow your ears out with sound even louder than the loudest Genesis Model 1s.
    Every Genesis will now be able to drive headphones, as well. The transistor buffers from the original design are gone, replaced by a TDA1308, a dual op-amp with a built-in headphone driver. It is this chip that is able to bring the higher volume and also simplify the design by integrating a superior headphone driver.
    The Mega Amp 2.0 retains the 3.68KHz low-pass filtering for Genesis Model 1-like audio on the filtered setup, but the unfiltered setup now goes beyond the audible spectrum, filtering frequencies past 24.56KHz for the clearest sound possible.
    The Mega Amp 2.0 is also available in a wider variety of versions. Along with the usual filtered/unfiltered setups, the Mega Amp 2.0 is available in three versions of varying complexity:

    Mini/Base





    This version follows the premise of the original Mega Amp with both Stereo and Mono output from the console. You can also make a Mini version by omitting the entire Mono audio circuit with the TL072, including the two 100ohm mixing resistors and 220uF capacitor.

    Pro





    This is the big one, the full-featured Mega Amp 2.0. It has it all: multiple different filter setups, Stereo and Mono audio, AND the added bonus of Sega CD audio mixing (Sega CD Model 2 or modded Sega CD Model 1 required to take advantage of this). Anyone who owns a Sega CD can choose what kind of audio they want out of their Genesis and Sega CD.

    To sum up the Mega Amp 2.0:
    -An even simpler design over the original Mega Amp (excluding the Mega Amp 2.0 Pro)
    -Filtered circuits deliver the same sound as a VA0 to VA2 Genesis Model 1 minus distortion
    -Unfiltered circuits deliver the full spectrum of the Genesis' audio output
    -The loudest audio levels of any audio amp for the Genesis, including Sega’s amp for the VA3 Genesis Model 1
    -Improved headphone support
    -Sega CD pass-through for the Mega Amp 2.0 Pro for a true replacement audio circuit with no loss in functionality
    -Mega Amp 2.0 Pro can add Sega CD pass-through to the Genesis Model 1

    Now for installation diagrams on consoles most in need of a new audio amp:

    VA7 Genesis Model 1 (use ASIC YM3438 version):




    VA0 Genesis Model 2 (use ASIC YM3438 version):




    VA1 & VA1.8 Genesis Model 2 (use ASIC YM3438 version):




    Note regarding the Sega CD passthrough on the Mega Amp 2.0 Pro with VA0, VA1 and VA1.8 boards: the necessary transistor circuits for the passthrough is already present on all of these motherboards. Do not build those shown in the schematics, instead, directly connect the outputs of U1a and U1b following this diagram:



    Use any of the indicated solder pads; they are all part of the same trace for the left and right audio inputs to the transistor circuits.

    VA2 Genesis Model 2 (use YM2612 version):



    VA2.3 Genesis Model 2 (use YM2612 version):



    VA3 Genesis Model 2 (use ASIC YM3438 version):



    VA4 Genesis Model 2 (use GOAC YM3438 version):





    VA1 Genesis 3 (use GOAC YM3438 version; system not compatible with the Mega Amp 2.0 Pro):





    VA2 Genesis 3 (use GOAC YM3438 version; system not compatible with the Mega Amp 2.0 Pro):




    Installation diagrams for GOAC-based Geniclones will be provided on the post below and diagrams for other official Sega hardware variants will be added to this post at a later date.

    As always, here are the obligatory audio samples. All samples taken using the Mega Amp 2.0 Pro:

    Sample Set 1
    Console used: VA3 Genesis Model 1
    FM chip: Discrete YM2612
    NOTE: This setup is unnecessary, but recommended if you want to add Sega CD audio passthrough on the Genesis Model 1 without using a patch cable.

    Sample Set 2
    Console used: VA0 Genesis Model 2
    FM chip: ASIC YM3438 in Sega 315-5660

    Sample Set 3
    Console used: VA4 Genesis Model 2
    FM Chip: GOAC YM3438 in Sega 315-5960
    NOTE: This console was the subject of a failed Neptune mod and has had much noisier audio since then. Background noise is not representative of what the end result is.

    In these samples, unfiltered audio is taken from the RCA outs of the Sega CD while filtered audio is taken from the console.

    For comparison, here are some samples from some stock Genesis motherboard revisions:

    VA3 Genesis Model 1
    VA0 Genesis Model 2 (LM324 op-amps)
    VA1 Genesis 3

    A PCB design is in progress and will be up for sale by May.
    Last edited by Ace; 10-20-2017 at 09:38 AM.
    HATES ATGAMES WITH A PASSION


    Mega Amp: An all-new audio circuit for your Sega Genesis/MegaDrive and clones.

    Note: If you want to contact me on Skype, identify yourself or your contact request will be rejected.

  2. #2
    Creator of the Mega Amp Raging in the Streets Ace's Avatar
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    Post reserved for GOAC-based Geniclones and other official Sega hardware variants.
    HATES ATGAMES WITH A PASSION


    Mega Amp: An all-new audio circuit for your Sega Genesis/MegaDrive and clones.

    Note: If you want to contact me on Skype, identify yourself or your contact request will be rejected.

  3. #3

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    I think it's finally time for me to pick one of these up.

  4. #4
    Hedgehog-in-Training Hedgehog-in-TrainingSports Talker vash999's Avatar
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    How much cost the mega amp board to va1 módel 2. Mini and pro model and how much shipping to Uruguay thx!

  5. #5
    Creator of the Mega Amp Raging in the Streets Ace's Avatar
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    I will have to assemble some boards to give you a price. Once I get a PCB design done and source the parts, I can give a price for the different versions.
    HATES ATGAMES WITH A PASSION


    Mega Amp: An all-new audio circuit for your Sega Genesis/MegaDrive and clones.

    Note: If you want to contact me on Skype, identify yourself or your contact request will be rejected.

  6. #6
    Outrunner Helder's Avatar
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    Excellent work Ace but there are a few typos on the Notes of the Pro Schematics mainly the filter values of the caps, it says 47pf and on schematic it's 28pf. One thing in the Sega CD Pass through that is a bit confusing is the mention of "U1a and U1b" where is that exactly? and All Pro versions need the A27 and B27 soldered to or is that the transistor circuit part of the schematic you were referring to to avoid for the VA0,VA1,VA1.8?

    The Mini version I assume is like the Original Mega AMP without the Sega CD Pass Through?

    Nice work on the circuit!

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    Road Rasher Chibisteven's Avatar
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    I've noticed with the model 2 is a faint background hum. Where the model 1 it's not there? Any chance on somebody ever fixing that?

  8. #8
    Creator of the Mega Amp Raging in the Streets Ace's Avatar
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    Quote Originally Posted by Helder View Post
    Excellent work Ace but there are a few typos on the Notes of the Pro Schematics mainly the filter values of the caps, it says 47pf and on schematic it's 28pf.
    Whoops, must be left over from an older prototype design. I'll fix that up.

    Also noticed I forgot to put a compatibility notice regarding the GOAC YM3438 Mega Amp 2.0 Pro on the Genesis 3 and other GOAC-based Geniclones with no Sega CD support. That's been added.

    Quote Originally Posted by Helder View Post
    One thing in the Sega CD Pass through that is a bit confusing is the mention of "U1a and U1b" where is that exactly? and All Pro versions need the A27 and B27 soldered to or is that the transistor circuit part of the schematic you were referring to to avoid for the VA0,VA1,VA1.8?
    U1a and U1b are two of the four op-amps in the TL074. Those are used as a preamp for FM, PSG and audio from the cartridge slot, after which the signal branches off into the transistor circuit to be passed into the Sega CD and the TDA1308 for the final output at the console. The transistor circuit is not necessary for VA0/VA1/VA1.8 boards as Sega already put one on the motherboard (you can remove the capacitors and 150ohm resistors, then move the 1Kohm resistors where indicated). For those, you just take the audio directly from U1a and U1b

    Quote Originally Posted by Helder View Post
    The Mini version I assume is like the Original Mega AMP without the Sega CD Pass Through?
    Not just the Sega CD passthrough omitted, but also the Mono mixing circuit. Mini is the bare minimum, which is just Stereo sound with the TDA1308.

    Quote Originally Posted by Chibisteven View Post
    I've noticed with the model 2 is a faint background hum. Where the model 1 it's not there? Any chance on somebody ever fixing that?
    If you're referring to the VA4 Genesis Model 2, it's been abnormally noisy since it was subjected to a failed Neptune mod. That noise shouldn't be there.
    Last edited by Ace; 01-02-2017 at 09:21 PM.
    HATES ATGAMES WITH A PASSION


    Mega Amp: An all-new audio circuit for your Sega Genesis/MegaDrive and clones.

    Note: If you want to contact me on Skype, identify yourself or your contact request will be rejected.

  9. #9
    Road Rasher Chibisteven's Avatar
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    Quote Originally Posted by Ace View Post
    If you're referring to the VA4 Genesis Model 2, it's been abnormally noisy since it was subjected to a failed Neptune mod. That noise shouldn't be there.
    I was referring to VA2 Genesis Model 2 with the Mega Amp 1.0 and that hum is present and noticeable in some samples provided that don't show up in the VA3 Genesis Model 1 stock or Mega Amp 2.0 versions.

  10. #10
    Hero of Algol TrekkiesUnite118's Avatar
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    Quote Originally Posted by Ace View Post
    U1a and U1b are two of the four op-amps in the TL074. Those are used as a preamp for FM, PSG and audio from the cartridge slot, after which the signal branches off into the transistor circuit to be passed into the Sega CD and the TDA1308 for the final output at the console. The transistor circuit is not necessary for VA0/VA1/VA1.8 boards as Sega already put one on the motherboard (you can remove the capacitors and 150ohm resistors, then move the 1Kohm resistors where indicated). For those, you just take the audio directly from U1a and U1b
    I'm a bit confused looking at this as well. So what exactly do you solder to? Any one of those three points? All three points?

  11. #11
    Creator of the Mega Amp Raging in the Streets Ace's Avatar
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    You can use any of the three points or even all three if you prefer a more solid solder joint. They're all part of the same trace on the PCB.
    HATES ATGAMES WITH A PASSION


    Mega Amp: An all-new audio circuit for your Sega Genesis/MegaDrive and clones.

    Note: If you want to contact me on Skype, identify yourself or your contact request will be rejected.

  12. #12
    Master of Shinobi Gentlegamer's Avatar
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    Sweet!

    Someone install this in my Genny plox.

  13. #13
    Framemeister Expert Hedgehog-in-TrainingOutrunner Tower of Power's Avatar
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    This is an amazing project, I just wish it was available in a way that was a bit more accessible and easier to take advantage of for the less technically inclined.
    Last edited by Tower of Power; 01-03-2017 at 10:50 AM.

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    Hedgehog-in-Training Hedgehog-in-TrainingSports Talker vash999's Avatar
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    sorry but i have a question of the schematic of mini amp .. to asic ym3438 Attachment 11930

    The down arrow is the ground signal? On the other hand the tda 1308 chip is 8 pin .. is there a pin "11" that goes to the ground signal? . Pin 4 of the tda 1308 chip goes towards 5 volts? when on the datasheet say it's going to gnd? Thanks for clarifying doubts to a newbie who is eager to try doing this but does not have much idea.

  15. #15
    Creator of the Mega Amp Raging in the Streets Ace's Avatar
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    That's wrong. It seems I erroneously reused the TL074 schematics. It's been corrected.
    HATES ATGAMES WITH A PASSION


    Mega Amp: An all-new audio circuit for your Sega Genesis/MegaDrive and clones.

    Note: If you want to contact me on Skype, identify yourself or your contact request will be rejected.

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