Molom Posted June 11, 2017 Report Share Posted June 11, 2017 After nine months of patiently sourcing components from around the world and several nights of soldering (and desoldering), I'm happy to say my MB-6582 is more or less finished. It's my first (working) diy synth, and I'm very satisfied with the results. Big thanks to TK, Wilba, and Smash TV for making this possible. It's populated with six 8580 R5s and two more are on their way. Things still left to do are: install the feedback pots and expansion port connector drill holes for the bottom vents and the 6.5mm audio jack eventually upgrade the cheap plasticky knobs install a display window install low profile heatsinks (can anyone point me to a source for these?) I also have one small issue - the filter cutoff value seems to jump around a bit when I change it, especially if I make slow adjustments. I've kept the detention on all my encoders. Is this behaviour normal? Quote Link to comment Share on other sites More sharing options...
jaytee Posted June 14, 2017 Report Share Posted June 14, 2017 Bravo! Looks awesome. Glad you got it working. Quote Link to comment Share on other sites More sharing options...
Molom Posted June 14, 2017 Author Report Share Posted June 14, 2017 Thanks Jaytee. Like you, I also had the problem that my LCD backlight wasn't dimming, but thanks to your thread earlier this year I learnt about the workaround with jumping B+ and B- with an LED. I'm already thinking about upgrading to an OLED. In addition to my question about the jumping filter cutoff values, I'm also wondering what exactly are the feedback pots supposed to do? I've used dual-gang 100K pots, but as far as I can tell all they do is mute the channel when turned hard one way. Am I missing something obvious here? Quote Link to comment Share on other sites More sharing options...
jaytee Posted June 15, 2017 Report Share Posted June 15, 2017 If you turn on the external input and route it to the filter, the feedback pots should introduce overdrive and additional resonance, especially in bandpass mode. I don't think it should ever go mute. Check your wiring, you can't go directly from the three pins of the pots to the three header pins. Quote Link to comment Share on other sites More sharing options...
Molom Posted June 16, 2017 Author Report Share Posted June 16, 2017 On 15/06/2017 at 4:44 PM, jaytee said: Check your wiring, you can't go directly from the three pins of the pots to the three header pins. Now I'm really confused. In all the pics I've seen it looks like the three pins of the pots are wired directly to the three header pins. Is something further necessary? Apologies for the noob questions, I'm just trying to understand how it works. Quote Link to comment Share on other sites More sharing options...
jaytee Posted June 19, 2017 Report Share Posted June 19, 2017 See here: The middle pin of the header is not the same as the middle pin on the pot. Quote Link to comment Share on other sites More sharing options...
Molom Posted June 19, 2017 Author Report Share Posted June 19, 2017 Ah! *headslap* I've seen that photo before, but I failed to notice the wiring at the pot. Thanks so much! Quote Link to comment Share on other sites More sharing options...
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