View Full Version : Sega CD audio waveforms (graphical comparison)

Joe Redifer
12-04-2007, 12:32 AM
OK I decided to see how various methods of connecting the Sega CD degraded audio quality. I recorded a clip from the first stage of Earnest Evans through the various ways using my model 1 Sega CD and model 1 Genesis:


The first image is the raw CDDA ripped straight from the disc. It cannot get any better than that, ever.

The second one is the music playing from the sound test of the game, and only the Sega CD RCA outputs are connected. The mixing jack was not used at all. Here you can see that the audio is substantially quieter and the dynamic range is decreased. I have always noticed this about the Sega CD... it is a very quiet CD player which forces you to turn the volume knob up a bit.

The third image is the system hooked up the same way, but the mixing jack and cable was used to connect the Genesis 1 to the Sega CD, and the volume slider is at 100% on the Genesis console. As you can see, there is no appreciable loss of sound quality and very, very little noise is added.

The final image (before the GIF loops and starts over) is with the mixing jack not used and all audio sent through the Genesis and out the headphone jack at maximum volume. You can see here that the dynamic range is even further limited and it is ever-so-slightly quieter as well.

Well, there you go! Have a fantastic day.

12-04-2007, 02:26 AM
Thanks for these. The 'genesis headphone jack' gif shows evidence of clipping. Maybe I should post some RMS noise graphs for each of my Genesis' afterall. BTW, what audio program did you use for those graphs?

Joe Redifer
12-04-2007, 03:19 AM
It's called Soundtrack Pro. It's part of Final Cut Studio on the Mac.

12-04-2007, 03:54 AM
So the best way to listen to Sega CD music while playing is to use the RCA jacks and mixing cable?

Joe Redifer
12-04-2007, 03:56 AM
Yes. That also allows you to lower the volume of annoying (and often way-too-loud) sound effects in games like Lord of Thunder and Lunar 1.

12-04-2007, 04:12 AM
MCD needs a sound mod... but I haven't any to mod....... everything needs some extra work on the sound circuits...

12-04-2007, 06:45 AM
Yes. That also allows you to lower the volume of annoying (and often way-too-loud) sound effects in games like Lord of Thunder and Lunar 1.

Yes. And the blipping arrows and commands in Road Avenger. The rest of the sound is quite awesome, so it must be done.

01-21-2008, 09:42 AM
I keep getting some fuzz and noise when I use the mixing cable/RCA method. I thought it was the audio on the cd, so I played it in my cd player and it sounded fine. What's happening? It just sounds...fuzzy. You can even hear it on the Sega CD loading screen. The mixing cable is just a regular 3.5mm stereo cable right? That is new and gold plated. The RCA cables are pretty new and clean. perhaps I should clean the RCA's out of teh sega cd?