That is so cool! Im currently working on building a modular synthesizer out of my old ddj 1000 flight case! Id love to learn more how you worked on the project in more detail. I dropped my email in the form!
There is many amateur arduino-programmers doing amazing stuff. There is a ton of Arduino nerds on the internet that have learnt from scratch by chatting with other nerds on the internet, downloading manuals showing how to build your own synths. There was magazines about how to build analogue synths in the eighties when I was a kid, kindof the same thing. If I tried the same thing I would have earn´t the money to buy a Juno before I´ve even finished the project itself.
Your problem with the analogue is from charge sharing between inputs. Give a little longer for each input to settle, put small capacitors to ground from each input(I.E.10Nf), and use lower resistances on your ADC inputs to combat the charge sharing. It puzzled me for a bit too, back around 26 years ago!
Long before the internet, Google, and CZcams, in the amateur radio community, we had the concept of an "Elmer". This was a benevolent individual who offered their knowledge to help new "hams" to kick-start sometimes daunting entry into the hobby. I applaud your tenacity and will to learn and meet your goal. Great work, and I'm sure you learned more than you may have expected. I hope you had your own "Elmer" to turn to for advice. As you mentioned, many times, even with professional designers (and in many fields), it can be quite easy to paint yourself into a corner. An extra set of eyes can oftentimes get you back on track after you have looked at it for the thousandth time. Best of luck to you, and keep on! You're doing great!
This is such a niche thing, I love it. You might be tapping into a specific subgroup of synth heads and homebrew engineers with this content such as I. Would like to see you build more synths!
If you want some places to start: I learned a lot about the software from Prajwal Mahesh, also Notes and Volts when I was getting started in hardware. (link at bottom) For i2c, this video helped me a lot: czcams.com/video/IyGwvGzrqp8/video.html And for designing pcb I learned a lot from just importing praj's board into Eagle (free with student license), and zooming in to see how he did stuff. Here's a short playlist that you can follow along czcams.com/play/PL_vPxziaK2fkAHkkC08F1jBsdSDWrQhph.html After trying a bunch of different ICs for input expansion (multiplexer, i2c gpio expanders), I feel like praj's method is still the best. He essentially bought the ATMEGA4809, the CPU from the Arduino nano, and then wrote his own firmware to use it to read inputs. It only costs $2 (at his time of build), and has 48 pins, so a lot more cost effective. It can also read interrupts which is good for rotary encoders, and it's a lot easier to debug since you can just run your code on a full ardunio. The firmware part sounds pretty intimidating, but once you learn i2c (and get a good gpio library), it's pretty doable (probably some examples online you can copy too). Good luck!!!!! tag me when you're done www.youtube.com/@prajwalmahesh90 www.youtube.com/@NotesAndVolts
Awesome, not only did you get a great synth, you got a great new pile of knowledge! And you shared it for other people to learn from. Super impressive and enjoyable to see.
you're braver than all! crazy challenge you achieved! i have looked into electronics when i started modular...i gave up when i grasped the amount of complexity layers. this is incredible what you achieved from scratch.
Dude, your ability to keep with it and work through your problems in public is awesome. Please keep documenting your journey, so inspiring for music peep and electronics alike. Let's go!
Rather misleading title. This isn't the equivalent of a $2000 Juno-106, it's the equivalent of a $60 Tal-U-No-LX licence (although in a very nice box).
So far well done, especially with little experience! You have a bounce problem and for the multiplexers you probably need to add some deadtime to make sure you are reading the signal from the pot or switch you intent to read from. On the bright side, for 99,9% sure it is all fixable by changing the software. Read pin, set multiplexer, WAIT, read next pin, etc...
Really impressed that you where able to recreate an expensive and complex midi device with off the shelf parts for under $200.00. What you did is not something typically taught in a University environment. Beyond that, I feel that your keen awareness to share this journey online with others here is priceless. I hope you continue to innovate and share future creations here for us to enjoy. Time for me to pull out my old Teensie and see what midi accessory I can reproduce. . .
@@HowToShopGreenthe oscillators are fully analog, they're just digitally controlled. not exactly the same thing as midi, as the original juno 6 didnt even have midi but still had digitally controlled oscillators. (DCOs) so while there is definitely a digital component, this device is more accurately described as an analog synth rather than a midi device.
@lorelei of the mist I understand your point about this being an analog synth. Like you said though, the original did not even come with a MIDI interface . At the end of the day be it analog, digital and MIDI based is a huge feet for under $100 and it works well. The synth I bought that had anything close to analog cost $600.00 which was a Casio XW-P1.
A quick search confirms that the Juno-106 has analog oscillators - and also has MIDI. Even “fully analog” synths can be controlled via MIDI via a MIDI-to-CV converter. @edwrdw, I gather that your home brew version uses digital oscillators? Once you get your hardware issues worked out, you can delve into virtual analog modeling in order to more accurately model the characteristics of the Juno’s oscillators and filters - not all are created equal! Awesome project 👍🏼👍🏼
Thank you for your explanation of multiplexing! I have always wondered what the process was, and your simple explanation was most helpful. Your progress through this project inspires me to start my own!
damn i love this so much. ive been through similar processes in diy hardware/software projects but i love the perseverance and the end result sounded sick too! good shit
I appreciate this video so much, as one attempting to build models like these on a much more grandiose scale, this is the most chock full informative video I've seen yet
This video and your efforts are so awesome in so many ways. Thank you for sharing not only your successes...but also your trial and tribulations. Looking forward to building your synth...and hope JLCPCB gives you some love when I order.
Super cool DIY project. Makes sense as something to do for fun and just to be able to say you made your own Juno 106 lol. Would love to see an analog version tho! Seems doable and even though you might not be able to get all the same components, you may end up with something even cooler!
Talk about an accelerated learning curve; so impressed my Canadian friend. Looking forward to any updates if you decide to polish this and squash the input bugs that appeared. Wonderful stuff.
I think the instability is coming from not having pull-down resistors on the multiplexer inputs. I've made a MUX circuit before to read a bunch of ultrasound distance sensors and the signals I was getting were all over the place,until I put some high-value (>10k as far as I can remember) resistors between each input and ground. You could bodge wire them to the pins of the THT parts so you don't have to solder to the fine-pitch IC, although you get extra cred if you do that :D
really cool man, well done getting it to where it is! in regards to the switches + keycaps, a standard keyboard layout is a 19.05mm grid, you can follow the cherry spec (and get the 3d models for a cherry switch) and in terms of keycaps, a typical rule of thumb is that they're 18mm (x/y), however some keycaps can be offset to that from manufacturing. If you're gonna build a case for this, ensure that you give your switches enough room from the edge of the case, that is typically 1mm, otherwise they will scrape against the case
“bluh bluh but its VIRTUAL analog” yeah and its still like a third of the price of the dang Roland Boutique. didn’t know teensy audio was so comprehensive, might look into making my own synths with this now 🤔
Yo thank you for acknowledging how much freaking work it takes to get over the CAD/PCB design part of circuit building. I feel pretty stuck here because it feels like you need to become pretty well versed in a lot of details from component libraries (both in your CAD and in your mental database of what's what) to CAD and 3D design to PCB layout. It's absurd and whenever I see a video of someone who went from knowing nothing to designing a PCB like it's no big deal I roll my eyes, so thanks for being forward about that part.
Sounds pretty far away from a Juno 106, but don’t let that take away from the fact that this is a amazing show of determination, The end result is fantastic, it’s Junoesque, so I’d say it was an absolute success.
Insanely cool project! I hope to eventually build something like that someday, though probably 10% of the complexity of this project. Impressive how far you got starting kind of from zero.
This is exactly the reason to get into a new field you don't have experience in like hardware/electronics/programming. You want a thing to exist but can't get it, so you make your own. A passion fueled relatively affordable project. Awesome stuff!
I'm making a guitar pedal form scratch and have run into many issues, tolerances, funky wiring to the IC, wonky footprints with small holes. 2 revisions later I still got the input and output jacks inverted. It sounds awesome so at least it's playable. I can't imagine trying to recreate a whole synth, great job!
For debouncing you can use a passive low pass filter placed between the button and pin as a hardware deboumcer. It's a cheap and easy solution that saves processing cycles on your microcontroller.
From the board to the editing, I love the homebuilt vibe to this video! For future iterations, I recommend trying to build and test subcomponents on a breadboard first. That way you can confirm each part works without errors. Only after should you try integrating it onto a PCB
Fantastic! The Juno was my first synth....... I took 12th grade highschool off, in order to go to a music store and buy one. Anyway........ I just wanted to say, this is the best video I have ever seen on this/these sorts of subject matter. Remember........ I am older than dirt. Old enough to have bought a Juno new. I have been studying this stuff since then. That is a long enough time span for me to have at least learned what a good instructional video Is. Congratulations Thank you
Bro the last thing i expected from watching this video is you triggering a core memory of fucking skylanders. That game was GOLD. I remember playing it so much as a kid and now i want to cry. Thanks bro 🤧. Also, amazing synth!
great vid, and brave you. as tube recording equpmt DIYer build past for over 300 machines, starting is harder than anything. want something badly helps you overcome that. you did it. not many can do, they only talk, ignore them. great work.
Nice video ^_^ The technical-creative side of sound design is definitely a niche-hitting section with not much competition. I've had a small interest in learning up these things, but first, I have to learn coding language :P Thinking about C++ and Python, although the homies down at Image-Line use Delphi, so I may have to look into that as well ' Which coding language are you using? :o
The issue with the mux's might be propegation delay. They take some time to update, and so you may be reading the value from the previous port if you change the selector input and read immediately? Might just need to change your polling function to read from the current port, then change port, so by the time it "ticks" again, the newly selected port is ready to read.
I was thinking about his mux problems and it might be due to handling 3 truth tables? Also thanks for this "change your polling function to read from the current port, then change port, so by the time it "ticks" again, the newly selected port is ready to read" I never actually cross my mind that you can change the polling rate, I'll use it in my gardener project :D
I'm very very impressed. I built a synth from a kit of parts and a PCB many years ago. It didn't work and I lacked the talent to resolve what was probably a myriad of issues. I enjoyed the process though.
I have built a few pcb's they can be a real pain to route properly. Auto route works sometimes but often not well. Especially with audio frequency on pins. To do this well is hard. But you definitely did something correct because it at least didn't smoke when you turned it on!! Cool project and congrats. Maybe V2 will be better? Also did you do a copper pour for the ground? One funny thing happens with pcb design often is capacitance along near by traces. Often 2 traces next to each other will act like a capacitor and one will build up a charge when the other is on or has frequency on it which sounds like may be what has happened to you there. The amount ok knowledge it takes to make a pcb is impressive.
Drop your email address for updates about this synth + new one (that's way cooler)
forms.gle/ntrVC7fAiz4T71zp9
Smart kid.
That is so cool! Im currently working on building a modular synthesizer out of my old ddj 1000 flight case! Id love to learn more how you worked on the project in more detail. I dropped my email in the form!
Hey mate, dropped my email on your list and am keen to see your updates = )
You can buy a Juno but you can’t buy the engineering talent to make everything in your home from scratch, you are on point little bro
if you all want is the sound then you can reproduce that if you know what you are doing
@@3dmaxuser lol that's what they just said
Except this is a programming based digital emulation.
There is many amateur arduino-programmers doing amazing stuff. There is a ton of Arduino nerds on the internet that have learnt from scratch by chatting with other nerds on the internet, downloading manuals showing how to build your own synths. There was magazines about how to build analogue synths in the eighties when I was a kid, kindof the same thing. If I tried the same thing I would have earn´t the money to buy a Juno before I´ve even finished the project itself.
@@LimneticVillains Still a very cool project tho.
Your problem with the analogue is from charge sharing between inputs. Give a little longer for each input to settle, put small capacitors to ground from each input(I.E.10Nf), and use lower resistances on your ADC inputs to combat the charge sharing. It puzzled me for a bit too, back around 26 years ago!
Long before the internet, Google, and CZcams, in the amateur radio community, we had the concept of an "Elmer". This was a benevolent individual who offered their knowledge to help new "hams" to kick-start sometimes daunting entry into the hobby. I applaud your tenacity and will to learn and meet your goal. Great work, and I'm sure you learned more than you may have expected. I hope you had your own "Elmer" to turn to for advice. As you mentioned, many times, even with professional designers (and in many fields), it can be quite easy to paint yourself into a corner. An extra set of eyes can oftentimes get you back on track after you have looked at it for the thousandth time. Best of luck to you, and keep on! You're doing great!
This is such a niche thing, I love it. You might be tapping into a specific subgroup of synth heads and homebrew engineers with this content such as I. Would like to see you build more synths!
same dude, this was a delight to stumble onto
Shit, as a software developer, I’ve always wanted to do something like this, so thanks for sharing your process 😁
you can do it!!!!! i believe in you!!!
If you want some places to start:
I learned a lot about the software from Prajwal Mahesh, also Notes and Volts when I was getting started in hardware. (link at bottom)
For i2c, this video helped me a lot: czcams.com/video/IyGwvGzrqp8/video.html
And for designing pcb I learned a lot from just importing praj's board into Eagle (free with student license), and zooming in to see how he did stuff. Here's a short playlist that you can follow along czcams.com/play/PL_vPxziaK2fkAHkkC08F1jBsdSDWrQhph.html
After trying a bunch of different ICs for input expansion (multiplexer, i2c gpio expanders), I feel like praj's method is still the best.
He essentially bought the ATMEGA4809, the CPU from the Arduino nano, and then wrote his own firmware to use it to read inputs.
It only costs $2 (at his time of build), and has 48 pins, so a lot more cost effective. It can also read interrupts which is good for rotary encoders, and it's a lot easier to debug since you can just run your code on a full ardunio. The firmware part sounds pretty intimidating, but once you learn i2c (and get a good gpio library), it's pretty doable (probably some examples online you can copy too).
Good luck!!!!! tag me when you're done
www.youtube.com/@prajwalmahesh90
www.youtube.com/@NotesAndVolts
Awesome, not only did you get a great synth, you got a great new pile of knowledge! And you shared it for other people to learn from. Super impressive and enjoyable to see.
That's a serious deep dive for a "starter" project ! I love the spirit.
you're braver than all! crazy challenge you achieved! i have looked into electronics when i started modular...i gave up when i grasped the amount of complexity layers. this is incredible what you achieved from scratch.
Thanks Edward 4 sharing your process and experiences! I really appreciate.
Dude, your ability to keep with it and work through your problems in public is awesome. Please keep documenting your journey, so inspiring for music peep and electronics alike. Let's go!
Rather misleading title. This isn't the equivalent of a $2000 Juno-106, it's the equivalent of a $60 Tal-U-No-LX licence (although in a very nice box).
So far well done, especially with little experience! You have a bounce problem and for the multiplexers you probably need to add some deadtime to make sure you are reading the signal from the pot or switch you intent to read from. On the bright side, for 99,9% sure it is all fixable by changing the software.
Read pin, set multiplexer, WAIT, read next pin, etc...
this is so awesome man the demo sounds so incredible!!
Really impressed that you where able to recreate an expensive and complex midi device with off the shelf parts for under $200.00. What you did is not something typically taught in a University environment. Beyond that, I feel that your keen awareness to share this journey online with others here is priceless. I hope you continue to innovate and share future creations here for us to enjoy. Time for me to pull out my old Teensie and see what midi accessory I can reproduce. . .
The Juno is an analog synth, not a midi device but, yeah it’s cool
You are correct in saying the Juno is an analog synth. It is also a complex midi device since it’s an analog synth with digital oscillators.
@@HowToShopGreenthe oscillators are fully analog, they're just digitally controlled. not exactly the same thing as midi, as the original juno 6 didnt even have midi but still had digitally controlled oscillators. (DCOs) so while there is definitely a digital component, this device is more accurately described as an analog synth rather than a midi device.
@lorelei of the mist I understand your point about this being an analog synth. Like you said though, the original did not even come with a MIDI interface . At the end of the day be it analog, digital and MIDI based is a huge feet for under $100 and it works well. The synth I bought that had anything close to analog cost $600.00 which was a Casio XW-P1.
A quick search confirms that the Juno-106 has analog oscillators - and also has MIDI. Even “fully analog” synths can be controlled via MIDI via a MIDI-to-CV converter.
@edwrdw, I gather that your home brew version uses digital oscillators? Once you get your hardware issues worked out, you can delve into virtual analog modeling in order to more accurately model the characteristics of the Juno’s oscillators and filters - not all are created equal! Awesome project 👍🏼👍🏼
nothing but love
Thank you for your explanation of multiplexing! I have always wondered what the process was, and your simple explanation was most helpful. Your progress through this project inspires me to start my own!
damn i love this so much. ive been through similar processes in diy hardware/software projects but i love the perseverance and the end result sounded sick too! good shit
Ooo! Looks like a fun build. Doesn't hurt that it sounds awesome!
I appreciate this video so much, as one attempting to build models like these on a much more grandiose scale, this is the most chock full informative video I've seen yet
This video and your efforts are so awesome in so many ways. Thank you for sharing not only your successes...but also your trial and tribulations. Looking forward to building your synth...and hope JLCPCB gives you some love when I order.
Such an awesome video. Really impressive that you've managed to go from zero to hero. Would love to see more of this content from you!
Super cool DIY project. Makes sense as something to do for fun and just to be able to say you made your own Juno 106 lol. Would love to see an analog version tho! Seems doable and even though you might not be able to get all the same components, you may end up with something even cooler!
This is awesome and rad on you for releasing your work.
Awesome, thanks for sharing and explaining the way you did!
Well done, thanks for taking the time to document it. :3
Talk about an accelerated learning curve; so impressed my Canadian friend. Looking forward to any updates if you decide to polish this and squash the input bugs that appeared. Wonderful stuff.
I hope you are inspired to keep making synths. Excellent work!!
This is so cool. I’ve been wanting to make my own synth for a while so this was really inspiring!
the outro is amazing. big fan. rewatched with one hand on loop
Yeah this is super inspiring! Thanks for this video and showing your talents!
Loved the demo! Great video!
Dude, nice build! Props for jumping into the deep end as a beginner.
Very nice project. I'd love to see the hardware documented once you get a chance to do a second revision of the board.
linked eagle files in desc
@@edwrdw Thank you :)
I think the instability is coming from not having pull-down resistors on the multiplexer inputs. I've made a MUX circuit before to read a bunch of ultrasound distance sensors and the signals I was getting were all over the place,until I put some high-value (>10k as far as I can remember) resistors between each input and ground. You could bodge wire them to the pins of the THT parts so you don't have to solder to the fine-pitch IC, although you get extra cred if you do that :D
really cool man, well done getting it to where it is! in regards to the switches + keycaps, a standard keyboard layout is a 19.05mm grid, you can follow the cherry spec (and get the 3d models for a cherry switch) and in terms of keycaps, a typical rule of thumb is that they're 18mm (x/y), however some keycaps can be offset to that from manufacturing. If you're gonna build a case for this, ensure that you give your switches enough room from the edge of the case, that is typically 1mm, otherwise they will scrape against the case
this is badass thanks for making this video and sharing your work
“bluh bluh but its VIRTUAL analog” yeah and its still like a third of the price of the dang Roland Boutique. didn’t know teensy audio was so comprehensive, might look into making my own synths with this now 🤔
Nice job. For not doing any of this before, you nailed it!
Well done 👏 I’ve always wanted to do this exact project!
Dude this was so rad, you snapped
Yo thank you for acknowledging how much freaking work it takes to get over the CAD/PCB design part of circuit building. I feel pretty stuck here because it feels like you need to become pretty well versed in a lot of details from component libraries (both in your CAD and in your mental database of what's what) to CAD and 3D design to PCB layout. It's absurd and whenever I see a video of someone who went from knowing nothing to designing a PCB like it's no big deal I roll my eyes, so thanks for being forward about that part.
Don't know why youtube recced this, but glad it did. Very cool video
The prices are so insane. I remember getting my 106 for like $350 in the late 2000's.
Sounds pretty far away from a Juno 106, but don’t let that take away from the fact that this is a amazing show of determination,
The end result is fantastic, it’s Junoesque, so I’d say it was an absolute success.
Insanely cool project! I hope to eventually build something like that someday, though probably 10% of the complexity of this project. Impressive how far you got starting kind of from zero.
Awesome!! Thanks for sharing this video, inspirational!
This is exactly the reason to get into a new field you don't have experience in like hardware/electronics/programming. You want a thing to exist but can't get it, so you make your own. A passion fueled relatively affordable project. Awesome stuff!
Overall great video, learnt some stuff, and you also recognized where you may have gone wrong which is great to hear
Love the turtle scene at the end. Encouraging video, thank you for your time invested.
I'm making a guitar pedal form scratch and have run into many issues, tolerances, funky wiring to the IC, wonky footprints with small holes. 2 revisions later I still got the input and output jacks inverted. It sounds awesome so at least it's playable. I can't imagine trying to recreate a whole synth, great job!
For debouncing you can use a passive low pass filter placed between the button and pin as a hardware deboumcer. It's a cheap and easy solution that saves processing cycles on your microcontroller.
nice man, the demo sounds cool !
Love this sort of stuff, and appreciate the detail. Subbed here!
From the board to the editing, I love the homebuilt vibe to this video! For future iterations, I recommend trying to build and test subcomponents on a breadboard first. That way you can confirm each part works without errors. Only after should you try integrating it onto a PCB
Dope tech. Thought I was done with the video but glad I stayed for the outro. kek
Amazing my dude. Inspirational
Whoaaaa amazing work 😲🤘🏽🔥
awesome video dude would love to see more!!
The fact that you've been able to do this much, is very impressive, keep your chin up.
You are truly a genius!
I really admire your work.
Sounds pretty amazing
Have you considered making your own Teensy Eurorack modules? I'm sure you could figure out something interesting to do or a multifunction module.
Amazing work, and you have turned it into a game of "Lights Out" !!!
Fantastic! The Juno was my first synth....... I took 12th grade highschool off, in order to go to a music store and buy one.
Anyway........ I just wanted to say, this is the best video I have ever seen on this/these sorts of subject matter.
Remember........ I am older than dirt. Old enough to have bought a Juno new. I have been studying this stuff since then. That is a long enough time span for me to have at least learned what a good instructional video Is.
Congratulations
Thank you
Fascinating video, you're very talented.
Great information, I used to solder PCB making MIDI stuff. Respect, SUBBED.
so sick, ive been thinking about making my own sequencer
great work man.
Bro the last thing i expected from watching this video is you triggering a core memory of fucking skylanders. That game was GOLD. I remember playing it so much as a kid and now i want to cry. Thanks bro 🤧. Also, amazing synth!
the outtro is so epic
I like how it sounds
Awesome man! New subscriber ✌🏻
sounds fantastic
beautiful work ❤
You have a lot of patience Edward!
This is insane, very cool
Great job!
Wow, I'm pretty impressed you were able to figure that all out by yourself. Most of that I had to be taught.
This is fire 🔥
Thanks
great vid, and brave you. as tube recording equpmt DIYer build past for over 300 machines, starting is harder than anything. want something badly helps you overcome that. you did it. not many can do, they only talk, ignore them. great work.
Whoaaaa that sounds WAY better than I'd expected. Followup video?
Nice video ^_^ The technical-creative side of sound design is definitely a niche-hitting section with not much competition.
I've had a small interest in learning up these things, but first, I have to learn coding language :P
Thinking about C++ and Python, although the homies down at Image-Line use Delphi, so I may have to look into that as well '
Which coding language are you using? :o
c++ in PlatformIO, very similar to Arduino Language but you get to organize it a lot better (class, templates, etc.)
That is a huge first hardware project
pretty cool project, thanks for sharing!
Very cool thanks for the awesome video.
More sounds, please. Amazing project. i like to have juno 106 too.
mad respect, mate
Awesome video, as an engineer and a synth nerd myself this is really cool to see.
Also I see you have a GCVI sweater, I went to Ross!
This is amazing m8
Great job my man! :D
The issue with the mux's might be propegation delay. They take some time to update, and so you may be reading the value from the previous port if you change the selector input and read immediately? Might just need to change your polling function to read from the current port, then change port, so by the time it "ticks" again, the newly selected port is ready to read.
I was thinking about his mux problems and it might be due to handling 3 truth tables?
Also thanks for this "change your polling function to read from the current port, then change port, so by the time it "ticks" again, the newly selected port is ready to read" I never actually cross my mind that you can change the polling rate, I'll use it in my gardener project :D
Agreed. The timings will be in the datasheet for the mux chip.
I'm very very impressed. I built a synth from a kit of parts and a PCB many years ago. It didn't work and I lacked the talent to resolve what was probably a myriad of issues. I enjoyed the process though.
I have built a few pcb's they can be a real pain to route properly. Auto route works sometimes but often not well. Especially with audio frequency on pins. To do this well is hard. But you definitely did something correct because it at least didn't smoke when you turned it on!! Cool project and congrats. Maybe V2 will be better? Also did you do a copper pour for the ground? One funny thing happens with pcb design often is capacitance along near by traces. Often 2 traces next to each other will act like a capacitor and one will build up a charge when the other is on or has frequency on it which sounds like may be what has happened to you there. The amount ok knowledge it takes to make a pcb is impressive.
I think you should document this for future reference. Also, you might think about getting together with a vendor to assemble and sell! looking good!
Dude that turtle at the end is dope.
You can’t really make a 106 using just a Teensy since it’s an analog synth with DCOs. However, I applaud your effort, this is a fun project.
Thanks for sharing
I've thumbed up at 0:29 ! you've earn it, man ! teensy at it's best !