32X PWM sound

[Joe Redifer]

Owners of the model 1 Genesis & Sega CD have always been able to simply lower the volume slider on the Genesis to isolate any sounds that the Sega CD is making. This is very entertaining for the curious, like me. But you can't do that with the 32X to see what sounds the extra hardware is providing to the extreme gaming experience that accompanies each and every 32X game. Well I've recorded a few examples for you using the space-age "MP3" format from the future. The Genesis audio has been stripped away, and only the 32X's PWM sound remains.

All audio recorded from real hardware:

After Burner (http://www.joeredifer.com/32X_PWM/afterburner.mp3) - 1.2MB
After Burner is perhaps the most impressive use of the 32X's sound capabilities EVAR! It makes nearly every sound heard except for some bass in the music and **maybe** some other backing instrument.

Space Harrier (http://www.joeredifer.com/32X_PWM/spaceharrier.mp3) - 463KB
The Genesis does most of the main melody in Space Harrier while the 32X does part of the music and nearly all of the sound effects. This is actually pretty impressive for the Genesis sound chip since the game sounds exactly like the arcade in every way. Hope you like drum 'n bass!

Virtua Fighter (http://www.joeredifer.com/32X_PWM/virtuafighter.mp3) - 816KB
The 32X does about what you'd expect it to do in this game, but for some reason the PWM chip buzzes a little (that's not my audio connection). Sometimes it turns the buzz off.

Knuckles' Chaotix (http://www.joeredifer.com/32X_PWM/chaotix.mp3) - 452KB
Yup, just the drums. The 32X also does just the sprites on the graphics side. The Genesis does far more with this game than the 32X does.

Blackthorne (http://www.joeredifer.com/32X_PWM/blackthorne.mp3) - 492 KB
The 32X seems to do almost every sound heard in this game.

Kolibri (http://www.joeredifer.com/32X_PWM/kolibri.mp3) - 332 KB
Part of the music and most of the sound effects are handled by the 32X.

Doom (http://www.joeredifer.com/32X_PWM/doom.mp3) - 152 KB
Yeah. Not much going on here.

It is interesting to note that the Genesis does all of the sounds (including the voices) in 36 Great Holes and Shadow Squadron. The 32X does only 1 sound in Virtua Racing, and that's during the Sega logo. All of the music and voices are 100% Genesis.

[Iron Lizard]

Thanks Joe. I have always been curious about what the 32x could actually do.

[evildragon]

Ahh, so you finally got B1 and B3? ;)

[Zebbe]

Owners of the model 1 Genesis & Sega CD have always been able to simply lower the volume slider on the Genesis to isolate any sounds that the Sega CD is making.

Genesis you mean. Or maybe you don't?

It was very interesting to listen to this. I've always thought the Mega Drive to be good enough to handle the Space Harrier sound, it seems I was almost right. I don't think it does much of the Sarah theme from Virtua Fighter though. Could you check it out?

[Joe Redifer]

Ahh, so you finally got B1 and B3? ;)
Yeah, I've been too lazy to take my Genesis apart and tape wires to the bottom until last night. I made my recording and now it's all been removed. By the way B1 is left and B3 is right.

I don't think it does much of the Sarah theme from Virtua Fighter though. Could you check it out?
Most of the other stages the 32X only does the drums, voices and sound effects. In her stage it is likely just the drums.

[Aarzak]

Wow, thanks a lot Joe. I too agree that "After Burner" makes the aural use of the 32X hardware as I've mentioned before. The stereo music and sound just SCREAM through my headphones. I don't mind the slowdown present in it and "Space Harrier" either, though AF32X is the only game that my PC can't run at full-speed on Kega Fusion. That includes all other Genesis/32X/Sega CD games, so I wouldn't know how AF32X looks at full speed.

Perhaps the portions of Genesis music/sfx in 32X games were of higher quality than normal (they sounded like it to me) by uh, being slightly boosted or helped out by the 32X sound hardware? That's just my theory, in terms of sample rates to be specific.

Also, I'm impressed that the Genesis handled the brunt of the work for "Knuckles Chaotix", but that's a compliment for the Genesis, and a strike against the 32X. Makes me wonder if cart versions of "Knuckles Chaotix" and "Sonic CD" (minus FMV, CD music and other SCD-strong features) could've been pulled off relatively well on vanilla Genesis hardware.

[Joe Redifer]

Sonic CD is technically the poorest performing Sonic game. It stutters a lot when scrolling and is full of weird quirks like that. I'm not sure why it's like that. Knuckles' Chaotix would have probably needed to sacrifice some BG colors to use for the sprites had it been a Genesis-only game. I'm fairly sure that the Genesis-generated graphics in that game use a combination of sprites + BGs to get the most colors possible. Turn off the 32X video and you'll see the Genesis is creating over 40 colors on the BGs, which is more color than the BGs are allowed to create.

[Aarzak]

Don't forget the "tosh", uncooperative and amateur hacker-esque level design. And the old, dusty Sonic 1 sprite? What gives?

[Tweaker]

The interesting thing about Knuckles Chaotix is that it uses the standard SMPS engine for its music, but literally just hacked to allow for PWM. By using the PWM for the drums, they were able to use all 6 FM channels on the YM2612, making the music a lot fuller. It probably also could have used sample hi-hats to free up the noise channel on the PSG (leaving the last tone available for use), but everyone has their limits, I guess. =P

Virtua Racing DX and Shadow Squadron also use the SMPS engine. This is probably why they use the DAC rather than the PWM for sampled aspects of the music.

[Genesis Knight]

That's a pretty neat rundown. Good job, Joe.

[megadriveworld]

Definitely interesting. Thanks.

Was always curious to see how they got the AfterBurner music to sound pretty much identical to the arcade.

[lilmul123]

I sure wish these weren't deleted; I'm pretty interested in hearing them.

[Dirt Ball Gamer]

Wow shadow squadron has nice music too, thats impressive its mostly genesis

[Joe Redifer]

I reuploaded to a new server. Try downloading them again.

[evildragon]

i know that buz joe.. 60hz hum, and it's in your doom sample too..

happens when the screen is whiter in some areas, your computer is merely picking it up from the VDP.

[MN12BIRD]

I always thought the SFX in 32x DooM where good yet the music blows. Now its clear why!

[evildragon]

The Genesis could have properly did the music, had they properly ported the music for the OPN2 (YM2612), and not the OPL2/OPL3...

[lilmul123]

What makes the sound chip in the 32x different from that in the genesis?

[evildragon]

What makes the sound chip in the 32x different from that in the genesis?
Uh, that's like asking why a CD is different than a DVD.

Genesis: PSG, FM, and DAC
32X: PWM
Sega CD: CDDA, PCM

[lilmul123]

Okay, let me rephrase that. How does PWM work for sound? I've never heard anything like that before.

The sound it seems to create is higher quality than FM, but it sounds scratchy...as if it was pre-recorded and brought down to 11025 Hz.

[evildragon]

Okay, let me rephrase that. How does PWM work for sound? I've never heard anything like that before.

The sound it seems to create is higher quality than FM, but it sounds scratchy...as if it was pre-recorded and brought down to 11025 Hz.
You should compare PWM to DAC, PCM.. FM is highly different..

PWM, just do a wikipedia search on it..

[Joe Redifer]

Most of those examples I posted sure don't sound scratchy to me. Tempo does sound like ass for some odd, incomprehensible reason, though.