About 2 years ago I decided to try and build a synthesizer. Where I would circuit bend and frame my synth around this. However, I decided against this due to practical reasons. Every circuit board has a different shape. I also realized power requirements can conflict drastically.
It can be done, but building a bit closer to scratch is better. I also decided against the big box transformer. I was able to get it to work. It required a 5amp fuse. Anything below this would burn from the secondary and its defualt start up.
Recent Events
A big break through has been finding mentors in piano and hammond organ repair. Basically a family who repair instruments. The wife does strictly piano repair. The husband does electronic instruments. His prefered stuff are the vacuum tubes. However, he has been upgrading hammonds to more modern circuitry when its just not possible to fix. As in lack of available parts.
I was taught beginning with the power supply testing. Via seeing if the voltage values are correct. Then the output circuitry and so on. Basically trying to find parts not functioning as they are supposed to. Leaky caps, reverse voltage issues on diodes, and loose wires.
With this I faced my fears with traditional transformers. After a few very basic experements with eBay purchased transformers I felt confident to wire up and solder the variable psu. The same one from MFOS. Other than calling in an electriciam for grounded outlets I felt several times more confident and safe.
The New Build
I still want to build a synth with the patch bay seperate. I also plan on it being fully pachable and modular. However, this means ribbon cables will connect io’s to their respective modules. With the exception of kits where its a bigger hastle to change then to leave be and designate areas specifically for them. Plus it will be multiple cabinets.
I spent a few all night sessions to keep a pace. Tonight I sort of did’t get arround to the “Synth Voice,” video. I really want to take it with me to my parents house to show it off. Which means it needes covers for all the empty spaces. Here is a few photos so far.
In the bottom right corner is a buck converter for a 5v rail. I used a bridge rectafier same as the MFOS variable supply. Then added diodes infront of the input. With capacitors to smooth out the AC to DC it works perfectly.
My Christmas gift I got is a midi to cv module. Which is why I wanted to get enough completed before I arrived to my parents house. An hour and 15min drive. However, the last hours of work on Christmas Eve morning was well worth it. I completly forgot my tool box, so I was only able to do adjustments.
I repaired the power distrobution board. A few bent wires was messing up two vco’s I had. After fixing I braved pluging in the brand new module. After the quick stuff of adding the Buck dc to dc converter for the 5v rail.
I did test it on a trusted Eurorack modular power supply first to rule out any problems to occure. Other then a very soft crackle sound in my cabinet it worked perfectly without to trusted psu I use mostly for debuging.
My Thoughts
I with there was a switch on the front for each cv and trigger group. There are jumper pins on the back with selecter pieces. Yet, it looks like you need a computer to change the functionality over all. However this is not a big deal.
I mostly wanted this to jumpstart my “cv,” type pannels. With this it should be a whole lot easier to build module and get to making patches right away. I will wait for a good day to fine tune this module.
Eventually I want to design and build a retro-modular comptuer for converting digital protocalls. Byte down on the programming and learn C/C++, ASM, and Python. “For easy number conversions,” before I insert the the groups of maping into the lower level code. I love descrete logic, but the programming has been time consuming to learn. When I really want a synth playable via a midi controller.
Lastly
A picture for the layout. My idea is to have wires and ribben cables to be neatly zip tied. Patch bays and seperate tile like pannels to make for easier access from the inside out.
As pictured one has mixing volumes via external patching. Then a dual synth voice with only right and left control. I cant fit two seperate volumes. So, adjusting both to ground on the center pin makes this easier.
Perhaps the downside to a patchbay is how much time it takes. Your doing every possible patch point possible. On pannel A of this cabinet “258,” is the magic number. I did not calculate any given number.
I honestly took another panel I had and went to town with a sharpie. After drilling and stepping things to fit I came to wiring 258. Pannel B is smaller. Basically the latter will focus on buffered multiples.
If Pannel A has any left over I will make vactrols and buffered multiples. I don’t think you can over do it with the two types. Plus those particular items don’t need another panel for knobs and switches.
I decided on making a stack of boards to connect the modules to the patch bays. Basically TL074’s to either bring up amplitude of signals or to buffer. The pannel connects via 16 pin ribbon cables. Then pcb headers to connect proto board to proto board.
The pictures show how I am mapping all this. Plus the first dual VCO’s I started. These will be loosely based off of LMNC’s recent video “Building a whole analogue synthesizer voice.” Instead of bread boards things are patched.
Making it very simplified. Only a switch for the cap on the FM and and a pitch knob. Then the second knob is the second vco. I will have cermet pots inside, but I hope to use vca type circiuts to attenuate the affect of things. In the video the primary method was Tl072’s to mix. I will breadboard this idea before I add it to all four dual vco’s.
