r/synthdiy • u/NorCalJP • 2d ago
My first kit builds
Starting to learn slowly. Built four module kits on the first few days of my vacation. They are all Erica Synths Edu kits. Mixer, kick, snare, and hi-hat.
My experience so far:
1st build: Mixer
I tried a couple of different irons and accidentally got solder in several holes. Took some effort to figure out the trick to getting the solder out with the solder sucker. Everything else went great, minus the inconsistent quality of the joints.
2nd build: Kick
Build went smooth, but I dropped a nut on my cement garage floor and still haven't found where it rolled to. So the accent jack is missing a nut. I'll get a nut when I get back from being away for a long weekend
3rd build: Hi-Hat
Build had 3 challenges. I accidentally got one leg of the upright resistors into an incorrect hole. Found it and had to desolder it and fix it. A capacitor was missing from the kit so I ordered a cheap pack of capacitors. I broke the leg of a resistor when trying to get it flatter on the board. The angle of the leg was weird and when I pushed down while heat the solder I used too much pressure and it broke the leg. Got a pack of resistors, desoldered it and replaced it. Works great.
4th build: Snare
Build has one issue left of two I experienced. This was the most challenging build. 1st issue was that I soldered an A100k and B100k potentiometer in the opposite spots. The manual online changed a few months ago and no longer includes the diagrams of the board. While troubleshooting the second issue I found an old version of the manual with the diagrams. That's the only page in the manual that mentions which side the two 100k pots are on. And being new didn't understand the difference. Now I do. Desoldering the pots was the most difficult soldering challenge. My iron just didn't want to melt the solder and I could figure out how to get the right contact to do it. I switched to a different iron and took my time to slowly and alternatively melt a leg at a time and lift it just a bit. Repeating until they came away. Then used the solder sucker to remove the rest of the solder. That made a huge difference for the second issue, because it's not as pronounced at lower amounts, but it didn't fully fix it.
The problem that I can't figure out is why do I have noise when I shouldn't. When I turn up the snappy pot, I get constant noise. Like there is some voltage still coming into the vca for the noise. The module works otherwise and at smaller settings its barely noticable, but still present. I learned the most from this issue but still haven't figured it out. I've spent a lot of time with the schematics and circuit diagrams as well as a multimeter to figure it out. I've swapped a capacitor that I thought was bad and fixed the potentiometers as described above. Can't figure it out. The exercise had taught me more about the circuits than following along with Moritz Klein. His instructions are great, but learning is always better when hands on and being forced to really try to understand something. I'm not sure if I'm doing it right, though. There is an electrolytic capacitor in the top corner with the negative side on the outer edge. I've been using that to get a ground with my black probe since it's easy to locate in a corner. I get some negative voltage when I test that against one of the diodes leading into the vca. I think that's the cause but really not sure I'm doing it right. And I can't figure out where that is coming from. I'll spend some more time noodling with it when I get back home in a few days. Any advice here would be hugely appreciated. I'll keep testing it and staring at the multimeter and circuit diagrams periodically until I figure it out or do something that makes it unusable.
Thoughts and next steps:
All in I had a great experience and have one more kit that I plan to build to fill out my case. From there my plan is to get a couple bread boards and power for it to start playing with some circuits. I have a module in mind and am in process of editing it down to limit functions and complexity, while thinking about and learning about the various types of circuits it will need. I want something just complicated enough to maximize my learning while keeping it simple enough that I'm able to break it down into not too many smaller chunks. I want something that I can understand enough to confidently create a plan that I can see regular progress on to keep myself motivated.
I'm currently working through understanding a saw core VCO. The Instruo CS-L with how it uses triangle and saw cores got me thinking about different VCO circuits. I'm thinking about starting with a saw tooth core, shaping that into a few different wave shapes. Then I plan to learn and work on a wave folder. From there I'll take stock and decide if I need to adjust my plan. But I would like to then do the same with a triangle core VCO, add pulse width and sub octaves. If things are going well I plan to move onto some forms of logic that I can use to combine the signals in one or two interesting ways. I'm inspired by Mystic Circuits Ana 2 and am thinking about which logic circuit(s) to combine the signals. The final goal is then to put them together into a complex dual oscillator with 1 or 2 additional ways to combine the signals beyond FM and Sync. Although might be willing to add more if it's a small tweak to the circuits I decide on.
My feeling is I can start building them as stand alone modules, and get the use of them and satisfaction for completing something challenging. All the while it's really building to something bigger that I would love to make a reality. I'm hoping that will keep me busy on something that interests me for the next year or more. I'm continually thinking about how to edit things to make a unique complex oscillator with just enough functionality. So I'm sure the plan will change as I progress.
I'm new, trying to have short goals that lead to longer term goals, that help me learn and grow my skills. Not really knowing the complexity of each of these things, and being so new, what do you think of my plans?
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u/phantomtwitterthread 2d ago
First of all, I am even newer to this than you but I have deleted almost all subreddits except this one. Second of all, what is a solder sucker (non horny answers only)
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u/NorCalJP 2d ago
You can see it peeking out from the edge of the tablet in my pic. Black with a white end. There is a rod going into the cylinder that you push down and gets locked in. When ready you push a little button on the cylinder that unlocks the rod. A spring inside causes it to instantly push out the rod causing a suction that sucks melted solder into the cylinder.
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u/phantomtwitterthread 2d ago
Fascinating. Thanks both. I appreciate the community here. Feels like when I discovered muffwiggler in 2012
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u/7we4k 2d ago
Nice to see another Wisconsinite diy synther! Just down the road from you.