SID differences?

[BassGuitari]

I was playing Blue Max on one of my backup C64s last night and noticed that one of the sound channels/voices is slightly different; the sounds of explosions (ex: bombing a building) and crashes are more harsh and "trebly" than on my other system, where they're warmer and have a slightly muffled quality by comparison (I actually prefer this). The other sounds--machine guns, cannon fire, engine, etc.--are the same, or close enough that I can't tell a difference.

 

So, the dumb question:

 

Are there variants of SID chips that are slightly different, or is there something else in the C64 architecture that would account for that difference (and can it be adjusted?)

[+OLD CS1]

Start here:

 

https://www.lemon64.com/forum/viewtopic.php?t=23866&sid=3bffe613d1fcc3556369b3fb9a82fd3e

[BassGuitari]

That answers all my questions. Thanks!

[+OLD CS1]

Cool. Here is a short break-down on some points.

 

The 6581 and 8580 use 12V and 9V, respectively. They both use different filter capacitors and the filter on the 8580 functions slightly different which allows for some new "features" after losing some of the 6581. Changing the volume on a channel of the 6581 caused a slight "pop" which could be manipulated for various purposes.