I’ve tried to assemble the synth that powers LMNC’s SID bass, the one with the design found here.
My build works with my nano SwinSID chip, but I can’t get it work with the original 6581 or 8580 chips (I have established that these chips are functioning).
When I try the 6581 or 8580, the sound is almost inaudible, with channels 1-3 able to output only brief gurgles. Channel 4 works a little better, but is still quiet and abrupt in its decay.
I’ve repeatedly gone over the schematic and compared my build to Brian Peters’s youtube videos, but I can’t find discrepancies.
Can anyone who has built this verify that the schematic worked for them without modification?
In the off chance that anyone could provide pictures of their build from more than one angle, this would also be helpful.
Thanks!
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Did you ever get this thing working? I’m having problems, too. It’s possible I got a bum chip off eBay. Wouldn’t be the first time, but then again the seller had a high rating and said it was tested and working. I went through the connection list and the schematic, double checked everything, and still got very little sound, and what little I did get was distorted and horrible. I took screen shots of Brian Peters’ synth and noticed there’s 3 resistors connected to ground that are not in the schematic or the connection list (pictured below, lower right hand side, all bunched up together). Huh? At any rate I hope I didn’t fry anything putting this together. Oddly enough the Teensy 2.0 still works fine, so that’s good. Oh well, I am a noob at this. I built the Little Scale Quad SN76489 recently and was so filled with confidence. This stuff is so far beyond my knowledge I was amazed I got it working. I had to build more, but as soon as I went with a project that threw a battery into the mix things headed south pretty quickly. The problem is likely the battery, too, because I replaced the 8580 with a SwinSID and it worked just fine, most likely because the SwinSID doesn’t require 9 volts to run. What can you do? I’ll get it eventually, right after I burn through my life’s savings in SID chips. That or I’ll have a 100% working SwinSID nano synth, which kind of sucks because the SwinSID nano is truly horrible.
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Welcome @CobraCommander! (Incidentally my elite pilot name back in the 80‘s)
This is not my area at all and im having all sorts of ideas about reference voltage and the ideal power set up for a SID. When in doubt I dig out the data sheet and look at working examples to see what I’ve done "differently. " keep going. You’ll get there!
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Cool, thanks for the encouragement! Ugh, why couldn’t I just be satisfied with my MSSIAH cart and my working breadbin Commodore 64? Because you can never have too many SID chip synths, that’s why!!! I mean, to be fair, you can take one look at mine and realize right away why it doesn’t work. Mom’s spaghetti! Look at that giant test hook clip! Why? And jeez, does this guy even know how to cut his own wire so all his jumpers aren’t three feet longer than they should be? What an amateur! To all of that I say I’m having fun, and that’s what matters. So what if my breadboard synth has tentacles and looks like something out of an H.P. Lovecraft novel? Will my SID chip synth ultimately be held together with popsicles sticks and chewing gum? You know it will be! It’s already the finest SwinSID synth ever built out of a ball of yarn!
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@CobraCommander still no luck here.
The three resistors on the bottom right seemed to have been set up in parallel to serve as the 330 kohm resistance for the EXT IN pin (follow the white wire).
But one resistor that doesn’t appear in the spec is the one on the top right of your screenshot. Looking at the red wire it’s connected to, (let me move your screenshot to the left)
it seems like Brian connected the negative side of the audio output capacitor to ground with a 1kohm resistor in addition to the positive side (which is already connected to ground with a 1kohm resistor as shown in the diagram). I tried adding a resistor with this placement, but it just reduced the volume slightly in the case of the nano SwinSID and did nothing in the case of the 8580. Seems to have no effect. I don’t know what else that resistor could be doing.
One strange thing I noticed while trying the 8580 is that I can unplug the 9v power source and still get the same crappy sound with only Teensy’s power source connected, just quieter. I wonder if this says anything about the circuit…
For now, I’ve resorted to getting a Hong Kong knock off Sammich SID kit from ebay for my c64 needs, but I haven’t assembled it yet.
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I took a screenshot of the other side, too! Makes me feel a little bit better and a little less inept knowing I’m not the only person who had problems. I was up last night looking for a solution and almost pulled the trigger on an ArmSID. I held off because it has an “auto-detect” feature that sets it to whichever C64 it’s been plugged into. Lord only knows if it can recognize that it’s supposed to be an 8580 when it’s plugged into this circuit. At this point I’d be 90% satisfied with the ArmSID but I’d have to read the specs a bit more to be sure. Ugh, SwinSID Nano. The filters on it are horrible! You’re better off just plugging it into an external filter. It’s not a C64 at that point but hey, better than nothing. On the plus side the drum samples slap, so at least there’s that. Really hoping to find the secret sauce that makes this thing functional! Also hoping I didn’t destroy my SID chip in the process. Is it possible we both got bum chips? I’ve gotten bogus SN76489’s before. It happens. Edit I also ordered polystyrene capacitors. Feeling not-so-environmentally-friendly at the moment and it probably won’t make a difference, but hey, at least I’ll be following this to the letter!
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