Because no one else has done this, I wanted to do it. The idea of the piggy backing a YM3438 on top of a YM2612 was my idea, however the method of how the pins are to be wired are not my idea. TmEE did the recommendation of tying /RD of the YM3438 to VCC and disconnecting it's /TEST pin. The reason for this mod, is that there are some bugs in the DAC of the YM2612, that make it more distorted that it needs to be, as it acts like it's less bits than it really is. The DAC in the YM3438 is good, but has a timer bug that causes problems with a few games, (either wrong tempo or no sound at all). So what this mod does, is use the YM2612 for timers, and the YM3438 for music. http://www.youtube.com/watch?v=8uEUiOzE294 Also the output of the YM3438 is different, so I had to from scratch come up with a plan on that, which is why it has the capacitor and resistors on it.
Do you have any before and after immediate examples? While what I'm hearing sounds good I don't know what it sounded like before.
Yes, though they are in game sound clips.. YM2612, the original chip: http://www.mediafire.com/?vo33cxci6s4euap YM3438, the new chip: http://www.mediafire.com/?j9scynj7kmll9n1 I think the biggest thing you'll hear is crisper "rings" sounds, and at the end, the last sound it plays before going silent, the extra life jingle, if you listen carefully, the quantization of the sound is different. Sadly though, the DAC channel, on the "SEEEEEGGGAAAAA" logo sounds scratchy on the YM3438. That can be fixed with better audio mixing, but I don't have the time for that. Ignore the extra cpu bus noise in the background on silent sounds, the YM3438 was breadboarded when those were recorded.
Hmm, here's a better A/B comparison. As I posted on another forum: First though, here's a rough AB comparison between the YM2612 and YM3438, with no music, select sound effects only. Ignore the noise levels please, I used a VA4 Japanese Mega Drive for the YM2612 test, and it has better filtering from VDP noise, as the one that's customized right now is a VA3, which isn't as good in VDP noise filtering. Also, since this VA3 Genesis is also overclocked, I turned off the overclock and had it running at stock speed. YM2612: http://www.mediafire.com/?9ioimgqx88rrgo0 YM3438: http://www.mediafire.com/?y19jpqfbdjazl4u YM3438 playing Mystic Cave Zone: http://www.mediafire.com/?ikoosno8gzr7npk The MP3's are constant bit rate, 320KBps and true stereo. Oh, and that stereo separation? If you use Audacity, you'll find I was telling the truth, as it's right in the wave form. YM3438 is better at stereo. YM2612: YM3438: Enjoy!
Mmm sounds very good indeed. Do we have a chance to get you doing (and telling us! ) better audio mixing to fix that scratchyness?
I honestly can't hear the difference, maybe I'm a lazy listener though. I did find it interesting that the YM3438 is already inside the TeraDrive of all things! Good old U44!
Don't do such a atrocity ! Replace the chip (take the YM2612 out and pop in the YM3438). Just need to change a tad the audio circuit (change the resistors as the YM3438 has different output circuitry). Besides that they're 100% equivalent circuit wise.
Late to reply, but no they aren't. You can't just "drop in a YM3438" into a model 1. I already tried it, it has bugs in the model 1 hardware. It NEEDS the YM2612 to do the responding, the 3438 is not 100% equivalent. Besides, the YM2612 I used had problems with it's audio outputs anyway, I didn't butcher an innocent chip. http://www.youtube.com/watch?v=8hqVWYwbZH8 http://www.youtube.com/watch?v=VBEkqSqgOL8 You will in my videos here why this is the case.
This is a very cool Mod, I have done it and puts the Model 1 in the top place over model 2 or 3 for having the best and most easily customizable audio.
