Hi again, i promised i would return soon with another newbie question
I am not having any luck finding a c64 psu and i was wondering if a can use a standard ATX pc power supply (which has seperate 5V and 12V outputs).
By the way i’m using 6581 so i need 12V instead of 9V. Theoritically i could connect the 5V output to the core module and the 12V output to the SID module.
Am I missing something? Will this work? I am not sure because I haven’t seen this idea implemented in any existing MBSID… ???
Thanks again and sorry if i’m being too stupid with my questions
The slightly more detailed answer is that while you will get the right voltages from this PSU, you’ll also get a lot of noise and ripple on the supply lines.
This noise will be clearly audible on the SID’s output.
Where do you live? I have several C64 PSUs, but I live a long way from most people. (Australia).
The thing that gets on my nerves most of all is that i used to own a C64C when I was young and sold it! So, now I have to search all over the world to find the SIDs (thank god i found 'em) and the PSU… It would have been a lot easier if I had my C64… :-\ anyway. Back in reality:
It makes perfect sense that an ATX PSU isn’t at all audio-optimized, but then again how do these professional PCI soundcards have such a perfect audio output? Isn’t there any power optimization circuit known? (like the one that minimizes noise on the C64 PSU)
some years ago I build a MB SID with AT PC Power Supply - the noise was terrible. After I replaced the Power Supply the annoying noise was gone. Just my experience.
Another point: the 12V supply is only stable by reference to the 5V. The 12 in a PC is for disc drive motors, fans etc. Not optimised for running audio. The soundcards usually have their own sub-regulators and lots of decoupling.
A final thought. On some cheap PC supplies the 12V can ‘glitch’ on power up, hitting 20V or so, not good for the delicate audio stuff.
