Introducing the Mega Amp - The universal Genesis audio circuit

[segasonicfan]

I have yet to get to the point of installing a Mega Amp in my own CDX, but I will have a look after I record all the necessary samples from the stock amp. A CDX could definitely benefit from a Mega Amp since the original circuit has bizzare filtering and lower sound output than any other Genesis I've ever heard.

Come to think of it, regardless of this, I should open my CDX since the laser looks to be failing and the lid can no longer stay open. When I get to this, I'll be sure to retrace the audio points.

Awesome. See my post here, it will save you a lot of work:
http://nfggames.com/forum2/index.php?topic=3719.40

Note, the 4 ply PCB is difficult to trace on, but with some patience I was able to do it pretty well.

[BlockABoots]

Thanks for the update info in the first post.

Have a question about the filtered variant of the mega amp, whats the point of the filtered version?, the unfiltered version sounds so much more cleaner and clearer compared to the filtered version??

[villahed94]

The filtered MegaAmp was created to replicate the sound of a Model 1 Genesis/MD on any Genesis-spec console. Ace prefers that setup and was the original way the MegaAmp was designed back in 2012.
I then came in and tweaked the circuit to make it work unfiltered and filtered without distortion.

[Chibisteven]

The sound that comes out of the model 1 is generally a warmer type of sound.

Some games benefit from being unfiltered, buts others sound like someone turned off the de-emphasis filter of an analog FM radio and sound kind of tinny or awful (fatigue inducing).

I say go with filtered unless you want a clearer sound, sharper than what was typical of that period in history.

[BlockABoots]

So there no way to have a switch with allows swapping between filtered and unfiltered?

[villahed94]

So there no way to have a switch with allows swapping between filtered and unfiltered?

Yes. A DPDT should do the trick. what should be done is as follows:
Disconnect or desolder one end of the capacitor, and add the other value. The switch will then swap between each capacitor.
This has to be done on each channel.

[Helder]

My board has both options on it and you just bridge 4 points to swap between the 2. I had one customer tell me he was going to use a 4 poll switch to connect to the solder bridge locations so he can go from one to the other easily.

[Kumagai]

Hi!

I have a clone of the asian Mega Drive model 1, with the A/V cable the vídeo quality is as good as an original one, but the overall audio quality in any of the audio outs are terrible...

How can I figure out if this clone is capable of a Mega Amp installation?

Thanks!

PS: Some pics of the console and his PCB:

MD09.JPG

pcb001.jpg

[ComradeOj]

I have a model 2 VA 2.3 that I just installed one of helder's unfiltered mega amps into.

The only problem is, I'm not getting any audio out of the right channel. Not even PSG.
I made sure all connections were good, but I still cant get any right audio out, even direct from the mega amp board.

Here is some images of my install from before, and after. http://imgur.com/a/ggP8K

Here is a sound sample I recorded from the second track in comix zone's sound test.
https://drive.google.com/file/d/0B-u...it?usp=sharing

Helder suggested I try asking in the Mega Amp thread.

[Chibisteven]

I have a model 2 VA 2.3 that I just installed one of helder's unfiltered mega amps into.

The only problem is, I'm not getting any audio out of the right channel. Not even PSG.
I made sure all connections were good, but I still cant get any right audio out, even direct from the mega amp board.

Here is some images of my install from before, and after. http://imgur.com/a/ggP8K

Here is a sound sample I recorded from the second track in comix zone's sound test.
https://drive.google.com/file/d/0B-u...it?usp=sharing

Helder suggested I try asking in the Mega Amp thread.

It's there pulsing on the right at a very low volume level (around -40 dB). You have a bad connection or component somewhere.

Try reflowing everything that effects it connection wise.

Also check things with a multi meter if you own one.

Change the wire? Last ditch effort of course.

Hopefully no traces are broken anywhere on any of the boards.

[ComradeOj]

It's there pulsing on the right at a very low volume level (around -40 dB). You have a bad connection or component somewhere.

Try reflowing everything that effects it connection wise.

Also check things with a multi meter if you own one.

Change the wire? Last ditch effort of course.

Hopefully no traces are broken anywhere on any of the boards.

I guess I'll start by testing continuity on the board. I tested the wires I used, and they're all good. There doesn't seem to be any audio coming off my Mega Amp's "RIGHT" solder point at all.

I also tested after burner on 32x to see if 32x PWM was working. It was, but again nothing came out on the right side.

[villahed94]

I guess I'll start by testing continuity on the board. I tested the wires I used, and they're all good. There doesn't seem to be any audio coming off my Mega Amp's "RIGHT" solder point at all.

I also tested after burner on 32x to see if 32x PWM was working. It was, but again nothing came out on the right side.

Please take a pic from the MegaAmp pcb to see if everything's ok.

[ComradeOj]

Please take a pic from the MegaAmp pcb to see if everything's ok.

Here are the pics of the front and back before install, as well as the front after install.

http://imgur.com/a/ggP8K

I have the higher res versions too, if you need them. Imgur scaled them down a bit.

[Helder]

I checked all traces where the output and op amp where on all the latest boards but might have missed yours. Anyways like I said if it still can't be fixed then I will exchange it for a known working one. I will provide the wiring for the left and right channels to help in troubleshooting the problem.

[ComradeOj]

I checked all traces where the output and op amp where on all the latest boards but might have missed yours. Anyways like I said if it still can't be fixed then I will exchange it for a known working one. I will provide the wiring for the left and right channels to help in troubleshooting the problem.

Thanks for the response, Helder!
Hopefully it is possible for me to just make a fix to the Mega Amp I already have.

If it's any help, I uploaded the original photos I took to my google drive, since Imgur lowers the resolution and uses more compression.
You can take a look at them here. https://doc-0k-as-docs.googleusercon...626&e=download