Hello Hybris, I made one of the first of these, using 8x 6582. A couple of thoughts I'd like to throw in:
- I didn't use any LED standoffs. Never had any trouble. Just put the LEDs loosely in the PCB, then screw on the front panel ... carefully turn the assembly over and all the LEDs just kind of fall into the front panel holes. Get 'em snug and solder. The leads are fairly rigid and should hold them in place.
- The front panel top-right "L / R" LEDs will collide with top right screw hole in the PT-10 case, so you need to grind a bit of it the plastic away.
- The weakest part of the design (IMHO) is the way the two boards connect together. I used very short flex cables. Others have used individual wires, ribbon cables, or pin headers and sockets so that you can take the two boards apart. But there's very little clearance between the boards, so you will just kind of have to live with two boards that don't come apart. (I would love to lay out a new panel board someday, with all the shift register ICs and resistor networks on it, which would connect to the main board using only about 5 wires.)
- The rear dual-gang feedback pots really can enhance the sound. Do not buy cheap pots for this. Slight movements can change the sound a fair bit, so you want to be sure that the paired-up pots are equal in value and taper. Buy brand-name for this application. I put cheap pots on mine and I regret it because I try to turn them all the way down but the left and right SIDs sound a little different from one another. I may replace mine with 3-position toggle switches (i.e. no feedback, 50% feedback, full feedback). I wish this could be made programmable somehow, using CMOS switches or digital pots or something.
- I have a fan and guard in my case. I couldn't get the motor noise out of my audio, so I disconnected it. That's the extent of my thermal management. It has never overheated.
- As mentioned above, don't use the C64 power supply. I still use one. It works OK, but my MB6582 has chewed through 3 separate Commodore bricks. That's right, I'm on my fourth. Back in the 1980s and 1990s, my C64 probably also outlived 2 or 3 power supplies, so they were never particularly reliable. I understand the European and Australian power supplies are a bit more robust than the North American ones. YMMV
- For the front panel, I did the JB Weld / standoff method as Wilba documented very well. That stuff is amazing. I haven't had a single standoff let go of the front panel, and there are no visible screws. I cleaned, then roughed up the surfaces of the back of the panel AND the standoffs using a wire brush or sandpaper prior to applying the fillets of JB Weld. Not sure if that helps make a stronger bond, but it certainly can't hurt. Also you need lots of clamps, and lots of patience.
- Next time I have mine open (soon, because I've got a flaky encoder or two), I plan to wire the 8 audio outputs so they also appear on the DB25 jack. Eventually I'll be able to use a single cable to connect my external box with 8 VCFs, 8 VCAs, AOUT and active summing and proper volume control (which the MB-6582 lacks). In the meantime I'll be able to use a snake like this: https://www.proaudiola.com/product-p/8-m2932-db-ts-2-p.htm ... Think about that panel mount DB25 connector, and what it can do for you. You can even use it for power if you like.
This is an awesome synth. I hope you have lots of fun with your build, as I did.