[stella] Interesting Music problem...

Subject: [stella] Interesting Music problem...
From: cybergoth@xxxxxxxx
Date: Tue, 25 May 2004 11:21:44 +0200 (CEST)
Hi there!

So when I wrote the Seawolf tune using Z26, it always sounded brilliant and crystal clear.

So I was realy shocked when I loaded it into the Cuttle Cart for the first time last week and it sounded horribly distorted. The voice-line "vibrated" very annoyingly, totally ruining the tune.

First I suspected a bug in my driver but after analysing it for hours and reading pages of the tracelog, to my surprise the driver did precisely what I wanted it to do.

I then experimented a lot and found this:

Each channel playing on his own sounded fine!

Then I found, I can even "destroy" the voice channel completely by once starting a single note straight after CLEAN_START:

LDA #$3A
LDA #$06
LDA #$0F

Very weird I thought.

I finally found a cure:

Turning the volume down. When the Seawolf tune is played with the voice on volume 10 and the bassline on volume 8, it is sounding acceptable.

Now I'm somewhat clueless about the whole thing. I'm suspecting something goes wrong in the monofying process on PAL consoles, when using voices 6 and 12 simultaniously. Could it possibly be that the waves distort or partially nullify each other or something like that?

Or is it more a volume thing, so both channels at highest volume will "override" (#1) the signals?
I assume worst case would be when the monofying process would simply sum up the amplitudes?

Anyone else ever run into something like this?


#1: No clue if this is the right term. I mean when the high peaks of the amplitude are getting truncated. Like when you turn up the volume too much when recording to an audio cassette... 

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