Posted By
Chicken
on 2009-10-12
10:13:15
 |  Yape 0.84 / Request for SID-card sample playback fix
While checking out Aefro-Mix I noticed that someone added a note "Needs a 6581 SID-Card!". This was a bit misleading because Solder's SID-card uses a 8580. However, it applies a simple "fix" so that samples can be heard. Only in emulators you should use the 6581 setting for now.
Gaia...
Could you please add SID digi playback to Yape for the 8580? Because that's what we get with a real SID-card anyway 
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Posted By
Gaia
on 2009-10-13
15:31:24
| Re: Yape 0.84 / Request for SID-card sample playback fix
Heh, thanks Chicken. It's been on my todo list for ages now, just never had the motivation to implement it. Perhaps now...
(actually, I do not know exactly how Solder's card implemented digi support either, so I figured as long as it's digi, it doesn't matter if it's a 6581 or a 8580  )
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Posted By
TLC
on 2009-10-13
15:42:04
| Re: Yape 0.84 / Request for SID-card sample playback fix
He implemented it by pulling the Audio In pin of the SID low(ish) using a resistor (see http://solder.dyndns.info/pub/files/commodore/plus4/hardware/SID-Card/Schematic_SID-card.gif). That puts a constant voltage level on the mixer... he might have taken that hack from C64 where it had been a problem that "new" C64s (8580) didn't play digi for long (they had already invented that method by then).
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Posted By
Gaia
on 2009-10-13
15:48:48
| Re: Yape 0.84 / Request for SID-card sample playback fix
Thanks, TLC. I suspected it was some DC added "somewhere" so it became the Audio In (what else) I figure you are referring to that 180 kOhm resistor. How does its level compare to that of the 6581 I wonder?
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Posted By
TLC
on 2009-10-13
16:07:14
| Re: Yape 0.84 / Request for SID-card sample playback fix
Evil knows that . It might have been selected empirically (similar digi volume level to 6581).
I suspect it might also contribute a fair amount of DC distortion to the end result (due to pulling the mixer's middle signal level from optimum) but I'm not sure yet (...and it's probably irrelevant here anyway).
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Posted By
Chicken
on 2009-10-13
16:53:35
| Re: Yape 0.84 / Request for SID-card sample playback fix
Yes, that "fix" was published in magazines like 64'er almost as soon as the new SIDs showed up.
Bionic, if I remember correctly, mentioned that it's a major source of distortion. Still, I can take those if I can have digis
Gaia,
it's not THAT important but if it has been on your list anyway...
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